阅读说明：本技术 用于方位波束宽度稳定的具有交错竖直阵列的带透镜基站天线 (Lensed base station antenna with staggered vertical array for azimuth beamwidth stabilization ) 是由 M·L·齐默尔曼 M·登宾斯基 于 2019-08-21 设计创作，主要内容包括：一种带透镜基站天线包括：第一阵列,所述第一阵列包括多个第一辐射元件,所述多个第一辐射元件配置成传输第一RF信号的相应子分量；第二阵列,所述第二阵列包括多个第二辐射元件,所述多个第二辐射元件配置成传输第二RF信号的相应子分量；以及RF透镜结构,所述RF透镜结构定位成从所述第一辐射元件中的第一个以及从所述第二辐射元件中的第一个接收电磁辐射。所述第一辐射元件的第一子集沿着第一竖直轴线对准,并且所述第一辐射元件的第二子集沿着与所述第一竖直轴线间隔开的第二竖直轴线对准。所述第一阵列和所述第二阵列各自包括每一水平行的单个辐射元件。(A lensed base station antenna comprising: a first array comprising a plurality of first radiating elements configured to transmit respective sub-components of a first RF signal; a second array comprising a plurality of second radiating elements configured to transmit respective sub-components of a second RF signal; and an RF lens structure positioned to receive electromagnetic radiation from a first one of the first radiating elements and from a first one of the second radiating elements. The first subset of the first radiating elements are aligned along a first vertical axis and the second subset of the first radiating elements are aligned along a second vertical axis spaced apart from the first vertical axis. The first and second arrays each include a single radiating element per horizontal row.)

1. A lensed base station antenna, comprising:

a first array comprising a plurality of first radiating elements configured to transmit respective sub-components of a first radio frequency ("RF") signal;

a second array comprising a plurality of second radiating elements configured to transmit respective sub-components of a second RF signal; and

an RF lens structure positioned to receive electromagnetic radiation from a first one of the first radiating elements and from a first one of the second radiating elements,

wherein a first subset of the first radiating elements are aligned along a first vertical axis and a second subset of the first radiating elements are aligned along a second vertical axis spaced apart from the first vertical axis, and

wherein the first array comprises a single radiating element for each horizontal row in the first array and the second array comprises a single radiating element for each horizontal row in the second array.

2. The lensed base station antenna of claim 1, wherein the first subset of the second radiating elements are aligned along a third vertical axis and the second subset of the second radiating elements are aligned along a fourth vertical axis spaced apart from the third vertical axis.

3. The lensed base station antenna of claim 2, wherein the first radiating element is mounted to extend forward from a first section of a reflector and the second radiating element is mounted to extend forward from a second section of the reflector, and wherein a front surface of a first plane defined by the first section of the reflector and a front surface of a second plane defined by the second section of the reflector intersect at an oblique angle.

4. The lensed base station antenna of claim 3, wherein the oblique angle is between 100 ° and 140 °.

5. The lensed base station antenna of claim 1, further comprising a plurality of first feed plates, each first feed plate having two or more of the first radiating elements mounted thereon, wherein a first subset of the first feed plates are aligned along the first vertical axis and a second subset of the first feed plates are aligned along the second vertical axis.

6. The lensed base station antenna of claim 1, wherein a horizontal distance between the first vertical axis and the second vertical axis is between 0.1 and 0.5 wavelengths of a center frequency of an operating band of the first radiating element.

7. The lensed base station antenna of claim 1, wherein a boresight pointing direction of a first one of the first radiating elements does not intersect a longitudinal axis extending through a center of the RF lens structure.

8. The lensed base station antenna of claim 1, wherein the RF lens structure comprises a cylindrical RF lens structure having a vertically extending longitudinal axis.

9. The lensed base station antenna of claim 1, wherein the operating frequency band of the first radiating element is within a 1.7-2.7GHz frequency band, and the horizontal distance between the first vertical axis and the second vertical axis is between 20-75 mm.

10. The lensed base station antenna of claim 1, wherein half of the first radiating element is aligned along the first vertical axis and the other half of the first radiating element is aligned along the second vertical axis.

11. The lensed base station antenna of claim 1, wherein a third subset of the first radiating elements are aligned along a third vertical axis that is between the first vertical axis and the second vertical axis.

12. The lensed base station antenna of claim 2, further comprising a third array comprising a plurality of third radiating elements configured to transmit respective sub-components of a third RF signal, wherein a first subset of the third radiating elements are aligned along a fifth vertical axis and a second subset of the third radiating elements are aligned along a sixth vertical axis spaced apart from the fifth vertical axis, and wherein the RF lens structure is positioned to receive electromagnetic radiation from a first one of the third radiating elements.

13. The lensed base station antenna of claim 1, wherein the RF lens structure comprises a plurality of elliptical RF lenses extending along a vertical axis.

14. The lensed base station antenna of claim 1, wherein the first array is configured to cover a first sub-sector of a 120 ° sector and the second array is configured to cover a second, different sub-sector of the 120 ° sector.

15. The lensed base station antenna of claim 1, wherein a minimum vertical separation between two vertically adjacent radiating elements aligned along the first vertical axis is greater than a minimum vertical separation between a radiating element aligned along the first vertical axis and a vertically adjacent radiating element aligned along the second vertical axis.

16. A lensed base station antenna, comprising:

a first radio frequency ("RF") port;

a first array comprising a plurality of radiating elements connected to the first RF port via a feed network, wherein a first vertical axis passing through a center of a first one of the radiating elements in the first array is spaced apart from a second vertical axis passing through a center of a second one of the radiating elements in the first array;

a second RF port;

a second array comprising a plurality of radiating elements connected to the second RF port via a feed network, wherein a third vertical axis passing through a center of a first one of the radiating elements in the second array is spaced apart from a fourth vertical axis passing through a center of a second one of the radiating elements in the second array; and

an RF lens structure positioned to receive electromagnetic radiation from at least one of the radiating elements in the first array and from at least one of the radiating elements in the second array.

17. The lensed base station antenna of claim 16, wherein the radiating elements of the first array are arranged in at least two columns and a plurality of rows, and at least some of the plurality of rows of radiating elements in the first array comprise a single radiating element, and wherein the radiating elements of the second array are arranged in at least two columns and a plurality of rows, and at least some of the plurality of rows of radiating elements in the second array comprise a single radiating element.

18. The lensed base station antenna of claim 17, wherein all of the plurality of rows of radiating elements in the first array comprise a single radiating element and all of the plurality of rows of radiating elements in the second array comprise a single radiating element.

19. The lensed base station antenna of claim 16, further comprising a plurality of first feed plates, each first feed plate having two or more of the radiating elements in the first array mounted thereon, wherein a first subset of the first feed plates are aligned along the first vertical axis and a second subset of the first feed plates are aligned along the second vertical axis.

20. The lensed base station antenna of claim 16, wherein a horizontal distance between the first vertical axis and the second vertical axis is between 0.1 and 0.5 wavelengths of a center frequency of an operating band of radiating elements in the first array.

21. The lensed base station antenna of claim 16, wherein the first array is configured to cover a first sub-sector of a 120 ° sector and the second array is configured to cover a second, different sub-sector of the 120 ° sector, and wherein a peak amplitude of an antenna beam generated by the first array is at an azimuthal angle that is offset from an azimuthal angle at a center of the first sub-sector.

22. The lensed base station antenna of claim 16, wherein half of the radiating elements in the first array are aligned along the first vertical axis and the other half of the radiating elements in the first array are aligned along the second vertical axis.

23. The lensed base station antenna of claim 16, wherein a subset of radiating elements in the first array are aligned along a third vertical axis that is between the first vertical axis and the second vertical axis.

24. The lensed base station antenna of claim 16, wherein at least some of the radiating elements in the first array are mounted to extend forward from a first section of a reflector and at least some of the radiating elements in the second array are mounted to extend forward from a second section of the reflector, and wherein a front surface of a first plane defined by the first section of the reflector and a front surface of a second plane defined by the second section of the reflector intersect at an oblique angle between 100 ° and 140 °.

25. The lensed base station antenna of claim 16, wherein a vertical spacing between two vertically adjacent radiating elements aligned along the first vertical axis is greater than a vertical spacing between a radiating element aligned along the first vertical axis and a vertically adjacent radiating element aligned along the second vertical axis.

26. A lensed base station antenna configured to transmit signals in both a low band and a high band, the lensed base station antenna comprising:

a first radio frequency ("RF") port;

a first array comprising a plurality of radiating elements connected to the first RF port via a feed network, each radiating element in the first array being vertically spaced from all other radiating elements in the first array; and

an RF lens structure positioned to receive electromagnetic radiation from at least one radiating element in the first array,

wherein at least some radiating elements of the first array are interleaved with other radiating elements of the first array in a horizontal direction and are positioned at a distance from the RF lens structure such that a first antenna beam generated by the first array in response to RF signals in the high frequency band is narrower in azimuth than a second antenna beam generated by the first array in response to RF signals in the low frequency band.

27. The lensed base station antenna of claim 26, further comprising:

a second array comprising a plurality of radiating elements connected to a second RF port via a second feed network, each radiating element in the second array being vertically spaced from all other radiating elements in the second array,

wherein the RF lens structure is further positioned to receive electromagnetic radiation from at least one radiating element in the second array, and

wherein at least some radiating elements in the second array are interleaved with other radiating elements in the second array in a horizontal direction.

28. The lensed base station antenna of claim 27, wherein the radiating elements in the first array are mounted to extend forward from a first section of a reflector and the radiating elements in the second array are mounted to extend forward from a second section of the reflector, and wherein a front surface of a first plane defined by the first section of the reflector and a front surface of a second plane defined by the second section of the reflector intersect at an oblique angle between 100 ° and 140 °.

29. The lensed base station antenna of claim 26, further comprising a plurality of first feed plates, each first feed plate having two or more of the radiating elements in the first array mounted thereon, wherein a first subset of the first feed plates are aligned along a first vertical axis and a second subset of the first feed plates are aligned along a second vertical axis.

30. The lensed base station antenna of claim 29, wherein a horizontal distance between the first vertical axis and the second vertical axis is between 0.1 and 0.5 wavelengths of a center frequency of an operating band of radiating elements in the first array.

31. The lensed base station antenna of claim 30, wherein half of the radiating elements in the first array are aligned along the first vertical axis and the other half of the radiating elements in the first array are aligned along the second vertical axis.

32. The lensed base station antenna of claim 26, wherein the first array is configured to cover a first sub-sector of a 120 ° sector and the second array is configured to cover a second, different sub-sector of the 120 ° sector, and wherein a peak amplitude of an antenna beam generated by the first array is at an azimuthal angle that is offset from an azimuthal angle at a center of the first sub-sector.

33. The lensed base station antenna of claim 26, wherein a vertical spacing between two vertically adjacent radiating elements aligned along a first vertical axis is greater than a vertical spacing between a radiating element aligned along the first vertical axis and a vertically adjacent radiating element aligned along a second vertical axis.

34. A lensed base station antenna, comprising:

a frame comprising a reflector;

at least one array of radiating elements mounted to extend forwardly from the reflector;

a radio frequency ("RF") lens mounted in front of the at least one array of radiating elements, the RF lens comprising: a lens housing having a body and a first lens end cap mounted on a first end of the body; and one or more RF focusing materials within the lens housing,

wherein the first lens end cap includes a first flange configured to mount the RF lens to the frame.

35. The lensed base station antenna of claim 34, wherein the body comprises fiberglass.

36. The lensed base station antenna of claim 34, wherein the first end cap further comprises a second flange, and wherein the first flange and the second flange are attached to the frame.

37. The lensed base station antenna of claim 36, wherein the lens housing further comprises a second end cap attached to a second end of the body opposite the first end, and the second lens end cap comprises a third flange and a fourth flange configured to mount the second end of the RF lens to the frame.

38. The lensed base station antenna of claim 34, wherein the first end cap is attached to the reflector.

39. The lensed base station antenna of claim 34, wherein the first flange comprises at least one mounting point.

40. The lensed base station antenna of claim 34, wherein the first lens end cap comprises a plurality of ribs.

Technical Field

The present invention relates generally to radio communications, and more particularly to lensed antennas for cellular and other communication systems.

Background

Cellular communication systems are well known in the art. In a typical cellular communication system, a geographical area is divided into a series of areas called "cells", each of which is served by a base station. The base station may include baseband equipment, radios, and a base station antenna configured to provide two-way radio frequency ("RF") communication with users located throughout a cell. In many cases, a cell may be divided into multiple "sectors," and separate base station antennas provide coverage for each sector. The antennas are typically mounted on a tower or other elevated structure, with the radiation beams ("antenna beams") generated by each antenna directed outward to serve a respective sector. Typically, a base station antenna comprises one or more phased arrays of radiating elements, wherein the radiating elements are arranged in one or more vertical columns when the antenna is installed for use. By "vertical" herein is meant a direction perpendicular with respect to a plane defined by the horizon.

A very common base station configuration is the so-called "three sector" configuration, in which the cell is divided into three 120 ° sectors in the azimuth plane, and the base station comprises three base station antennas providing coverage for the three respective sectors. The azimuth plane refers to a horizontal plane that bisects the base station antenna and is parallel to a plane defined by the horizon. In a three sector configuration, the antenna beam generated by each base station antenna typically has a half power beam width ("HPBW") in an azimuth plane of about 65 °, such that the antenna beam provides good coverage for the entire 120 ° sector. Typically, each base station antenna will comprise a vertically extending column of radiating elements, commonly referred to as a "linear array". Each radiating element in the linear array may have an HPBW of approximately 65 °, such that an antenna beam generated by the linear array will provide coverage over a 120 ° sector in the azimuth plane.

Sector splitting refers to a technique in which the coverage area of a base station is divided into more than three sectors, such as six, nine, or even twelve sectors. A six sector base station will have six 60 sectors in the azimuth plane. Dividing each 120 sector into multiple smaller sub-sectors increases system capacity because each antenna beam provides coverage over a smaller area, thus providing higher antenna gain and/or allowing frequency reuse within the 120 sector. In sector splitting applications, a single multi-beam antenna is typically used for each 120 sector. A multi-beam antenna generates two or more antenna beams within the same frequency band, thereby dividing a sector into two or more smaller sectors. Sector splitting typically requires a multi-column array of radiating elements. Two common methods of sector splitting are sector splitting using a beam forming network such as a Butler matrix (Butler matrix) and sector splitting using a lensed antenna.

In a first sector splitting approach, a multi-column array of radiating elements is driven by a feed network that includes a Butler matrix or other beam forming network to generate two or more antenna beams from the multi-column array. For example, if a multi-column array is used to generate two side-by-side antenna beams each having an azimuth HPBW of about 33 °, a six-sector configuration may be implemented using three base station antennas. For example, an antenna having a multi-column array that generates a plurality of beams is disclosed in U.S. patent publication No. 2011/0205119.

In a second sector splitting method, an RF lens is included in the base station antenna, and the plurality of linear arrays are configured to transmit and receive signals in different directions through the RF lens. The RF lens may be used to reduce the azimuth beamwidth of the antenna beam generated by the linear array to a beamwidth suitable for providing service to the sub-sector. Thus, for example, for a six sector base station served by three base station antennas, the RF lens would be designed to narrow the azimuth HPBW of each antenna beam to about 33 °.

The application of a multi-beam antenna may require minimal azimuth interleaving to cover the sector while reducing interference. The "cross" performance of antenna beams generated by a multi-beam antenna refers to a reduction from a peak gain level at points (in the azimuth plane) where the antenna beam and an adjacent antenna beam have the same gain. For example, if the azimuth maps of two adjacent antenna beams cross each other at a level 10dB below the peak gain of the azimuth maps, the multi-beam antenna will have a 10dB cross. However, each of the above approaches for sector splitting may not provide acceptable cross-performance, particularly if the antenna comprises a wideband array operating over a large frequency band.

Disclosure of Invention

According to an embodiment of the present invention, there is provided a lensed base station antenna including: a first array comprising a plurality of first radiating elements configured to transmit respective sub-components of a first RF signal; a second array comprising a plurality of second radiating elements configured to transmit respective sub-components of a second RF signal; and an RF lens structure positioned to receive electromagnetic radiation from a first one of the first radiating elements and from a first one of the second radiating elements. The first subset of the first radiating elements are aligned along a first vertical axis and the second subset of the first radiating elements are aligned along a second vertical axis spaced apart from the first vertical axis. The first array includes a single radiating element for each horizontal row in the first array, and the second array includes a single radiating element for each horizontal row in the second array.

In some embodiments, the first subset of the second radiating elements are aligned along a third vertical axis and the second subset of the second radiating elements are aligned along a fourth vertical axis spaced apart from the third vertical axis.

In some embodiments, the first radiating element is mounted to extend forwardly from the first section of the reflector, the second radiating element is mounted to extend forwardly from the second section of the reflector, and a front surface of a first plane defined by the first section of the reflector and a front surface of a second plane defined by the second section of the reflector intersect at an oblique angle. In some embodiments, the oblique angle may be between 100 ° and 140 °.

In some embodiments, the lensed base station antenna may further include a plurality of first feed plates. Each first feed plate has two or more of the first radiating elements mounted thereon, wherein a first subset of the first feed plates are aligned along the first vertical axis and a second subset of the first feed plates are aligned along the second vertical axis.

In some embodiments, a horizontal distance between the first vertical axis and the second vertical axis is between 0.1 and 0.5 wavelengths of a center frequency of an operating band of the first radiating element.

In some embodiments, a boresight pointing direction of a first one of the first radiating elements does not intersect a longitudinal axis extending through a center of the RF lens structure.

In some embodiments, the RF lens structure comprises a cylindrical RF lens structure having a vertically extending longitudinal axis.

In some embodiments, the operating frequency band of the first radiating element is within the 1.7-2.7GHz frequency band, and the horizontal distance between the first vertical axis and the second vertical axis is between 20-75 mm.

In some embodiments, half of the first radiating elements are aligned along the first vertical axis and the other half of the first radiating elements are aligned along the second vertical axis.

In some embodiments, the third subset of the first radiating elements are aligned along a third vertical axis between the first and second vertical axes.

In some embodiments, the lensed base station antenna may further include a third array including a plurality of third radiating elements configured to transmit respective sub-components of a third RF signal. In these embodiments, the first subset of the third radiating elements may be aligned along a fifth vertical axis, the second subset of the third radiating elements may be aligned along a sixth vertical axis spaced apart from the fifth vertical axis, and the RF lens structure may be positioned to receive electromagnetic radiation from the first one of the third radiating elements.

In some embodiments, the RF lens structure may include a plurality of elliptical RF lenses extending along a vertical axis.

In some embodiments, the first array may be configured to cover a first sub-sector of a 120 ° sector and the second array may be configured to cover a second, different sub-sector of the 120 ° sector.

In some embodiments, a minimum vertical spacing between two vertically adjacent radiating elements aligned along the first vertical axis may be greater than a minimum vertical spacing between a radiating element aligned along the first vertical axis and a vertically adjacent radiating element aligned along the second vertical axis.

According to a further embodiment of the present invention, there is provided a lensed base station antenna, including: a first RF port; a first array comprising a plurality of radiating elements connected to the first RF port via a feed network, wherein a first vertical axis passing through a center of a first radiating element in the first array is spaced apart from a second vertical axis passing through a center of a second radiating element in the first array; a second RF port; and a second array comprising a plurality of radiating elements connected to the second RF port via a feed network, wherein a third vertical axis passing through a center of a first radiating element in the second array is spaced apart from a fourth vertical axis passing through a center of a second radiating element in the second array. These antennas also include an RF lens structure positioned to receive electromagnetic radiation from at least one radiating element in the first array and from at least one radiating element in the second array.

In some embodiments, the radiating elements of the first array may be arranged in at least two columns and rows, at least some of the rows of radiating elements in the first array may include a single radiating element, and the radiating elements of the second array may likewise be arranged in at least two columns and rows, at least some of the rows of radiating elements in the second array may include a single radiating element.

In some embodiments, all of the plurality of rows of radiating elements in the first array comprise a single radiating element and all of the plurality of rows of radiating elements in the second array comprise a single radiating element.

In some embodiments, the lensed base station antenna may further include a plurality of first feed plates, each first feed plate having two or more radiating elements of the first array mounted thereon. In these embodiments, a first subset of the first feed plates may be aligned along the first vertical axis and a second subset of the first feed plates may be aligned along the second vertical axis.

In some embodiments, a horizontal distance between the first vertical axis and the second vertical axis may be between 0.1 and 0.5 wavelengths of a center frequency of an operating band of radiating elements in the first array.

In some embodiments, the first array may be configured to cover a first sub-sector of a 120 ° sector, the second array may be configured to cover a second, different sub-sector of the 120 ° sector, and the peak amplitude of the antenna beam generated by the first array is at an azimuthal angle that is offset from the azimuthal angle at the center of the first sub-sector.

In some embodiments, half of the radiating elements in the first array may be aligned along the first vertical axis and the other half of the radiating elements in the first array may be aligned along the second vertical axis.

In some embodiments, a subset of the radiating elements in the first array may be aligned along a third vertical axis between the first and second vertical axes.

In some embodiments, at least some of the radiating elements in the first array are mounted to extend forwardly from the first section of the reflector, at least some of the radiating elements in the second array are mounted to extend forwardly from the second section of the reflector, and a front surface of a first plane defined by the first section of the reflector and a front surface of a second plane defined by the second section of the reflector intersect at an oblique angle between 100 ° and 140 °.

In some embodiments, a vertical spacing between two vertically adjacent radiating elements aligned along the first vertical axis may be greater than a vertical spacing between a radiating element aligned along the first vertical axis and a vertically adjacent radiating element aligned along the second vertical axis.

According to still other embodiments of the present invention, lensed base station antennas are provided that are configured to transmit signals in both a low frequency band and a high frequency band. These antennas include: a first RF port; a first array comprising a plurality of radiating elements connected to the first RF port via a feed network, each radiating element in the first array being vertically spaced from all other radiating elements in the first array; and an RF lens structure positioned to receive electromagnetic radiation from at least one radiating element in the first array. At least some radiating elements of the first array are interleaved with other radiating elements of the first array in a horizontal direction and are positioned at a distance from the RF lens structure such that a first antenna beam generated by the first array in response to RF signals in the high frequency band is narrower in azimuth than a second antenna beam generated by the first array in response to RF signals in the low frequency band.

In some embodiments, the lensed base station antenna further comprises a second array comprising a plurality of radiating elements connected to a second RF port via a second feed network, each radiating element in the second array being vertically spaced apart from all other radiating elements in the second array. In such embodiments, the RF lens structure is further positioned to receive electromagnetic radiation from at least one radiating element in the second array, and wherein at least some radiating elements in the second array are interleaved with other radiating elements in the second array in a horizontal direction.

In some embodiments, the radiating elements in the first array may be mounted to extend forwardly from the first section of the reflector and the radiating elements in the second array may be mounted to extend forwardly from the second section of the reflector, and wherein a front surface of a first plane defined by the first section of the reflector and a front surface of a second plane defined by the second section of the reflector intersect at an oblique angle of between 100 ° and 140 °.

In some embodiments, the lensed base station antenna further comprises a plurality of first feed plates, each first feed plate having two or more radiating elements in the first array mounted thereon, wherein a first subset of the first feed plates are aligned along a first vertical axis and a second subset of the first feed plates are aligned along a second vertical axis.

In some embodiments, a horizontal distance between the first vertical axis and the second vertical axis may be between 0.1 and 0.5 wavelengths of a center frequency of an operating band of radiating elements in the first array.

In some embodiments, half of the radiating elements in the first array may be aligned along the first vertical axis and the other half of the radiating elements in the first array may be aligned along the second vertical axis.

In some embodiments, the first array may be configured to cover a first sub-sector of a 120 ° sector and the second array may be configured to cover a second, different sub-sector of the 120 ° sector. In these embodiments, the peak amplitude of the antenna beams generated by the first array may be at an azimuth angle that is offset from the azimuth angle at the center of the first sub-sector.

In some embodiments, a vertical spacing between two vertically adjacent radiating elements aligned along a first vertical axis may be greater than a vertical spacing between a radiating element aligned along the first vertical axis and a vertically adjacent radiating element aligned along a second vertical axis.

According to a further embodiment of the present invention, there is provided a lensed base station antenna, including: a frame comprising a reflector; at least one array of radiating elements mounted to extend forwardly from the reflector; and an RF lens mounted in front of the at least one array of radiating elements, the RF lens comprising: a lens housing having a body and a first lens end cap mounted on a first end of the body; and one or more RF focusing materials within the lens housing. The first lens end cap includes a first flange configured to mount the RF lens to the frame.

In some embodiments, the body comprises fiberglass.

In some embodiments, the first end cap further comprises a second flange, and the first flange and the second flange are attached to the frame.

In some embodiments, the lens housing further comprises a second end cap attached to a second end of the body opposite the first end, the second lens end cap comprising third and fourth flanges configured to mount the second end of the RF lens to the frame.

In some embodiments, the first end cap is attached to the reflector.

In some embodiments, the first flange includes at least one mounting point.

In some embodiments, the first lens end cap includes a plurality of ribs.

Drawings

Fig. 1A and 1B are schematic top views of a lensed base station antenna, showing how the variation of the azimuth beamwidth of a linear array with frequency can be used to provide azimuth beamwidth stability.

Fig. 2 is a perspective view of a lensed multi-beam base station antenna with a radome removed according to an embodiment of the invention.

Fig. 3 is a perspective view of the lensed multi-beam base station antenna of fig. 2 with the RF lens structure also removed.

Fig. 4 is a cross-sectional view of the lensed multi-beam base station antenna of fig. 2.

Fig. 5A-5C are a series of graphs illustrating the improvement in azimuth beamwidth stability that can be achieved by using staggered vertical arrays according to embodiments of the present invention.

Fig. 6 is a schematic perspective view of a lensed base station antenna similar to the antennas of fig. 2-4, except that the antenna of fig. 6 includes a conventional linear array of radiating elements.

Fig. 7 is a schematic diagram of an azimuth map of antenna beams generated by one of the staggered vertical arrays of lensed base station antennas of fig. 2-4.

Fig. 8 is a schematic cross-sectional view of a modified version of the lensed multi-beam base station antenna of fig. 2.

Fig. 9 is a schematic illustration of a lensed base station antenna comprising an interleaved vertical array that implements interleaving based on a single radiating element rather than on a feed plate.

Fig. 10 is a schematic front view of a lensed base station antenna according to a further embodiment of the invention.

Fig. 11 is a schematic illustration of a lensed base station antenna including a staggered array that positions radiating elements along three different vertical axes in accordance with an embodiment of the present invention.

Fig. 12 is a schematic perspective view of a lensed base station antenna including an elliptical RF lens array according to some embodiments of the invention.

Fig. 13 is a schematic front view of one of the staggered vertical arrays of radiating elements included in the base station antenna of fig. 2-4.

Fig. 14A-14D are perspective and end views illustrating a conventional method for supporting a cylindrical RF lens within a base station antenna.

Fig. 15A-15B are interior and exterior views of an RF lens end cap according to an embodiment of the present invention.

Fig. 15C is a cross-sectional view of a portion of an RF lens housing including the lens end cap of fig. 15A-15B.

Fig. 16A-16C are various views showing how an RF lens including two of the lens end caps of fig. 15A-15C may be mounted within a base station antenna.

Detailed Description

While RF lenses provide a convenient mechanism for implementing sector splitting, various difficulties may arise in the practice of attempting to use a lensed multi-beam antenna. One such difficulty is achieving acceptable cross-over performance, particularly for base station antennas operating in the 1.7-2.7GHz band (or other wide band). Generally, the azimuth beamwidth of the antenna beam generated by the radiating element will decrease as the frequency of the RF signal generating the antenna beam increases. However, to provide azimuth beamwidth stability, most radiating elements are designed to counteract this effect, such that the antenna beam generated by the radiating element will have a relatively constant beamwidth in the azimuth plane at the operating frequency of the radiating element. Designing the radiating element such that it generates an antenna beam having a relatively stable azimuthal beam width over the operating frequency band helps to ensure that acceptable crossover performance is achieved for RF signals at all frequencies within the operating frequency band.

The amount of RF energy focused by the RF lens varies with the frequency of the RF signal, with increasing focusing of the RF energy (and thus narrowing of the azimuth beam width) occurring as the frequency increases. Thus, the RF lens will tend to focus more RF energy in the upper portion of the operating band than in the lower portion of the operating band, making it difficult to achieve acceptable crossover performance over the entire operating band if the radiating elements are designed to generate antenna beams with relatively constant azimuthal beamwidth over the operating band. Where the operating band is large (e.g., the 1.7-2.7GHz band), it may be particularly difficult to achieve acceptable crossover performance across the entire operating band.

U.S. patent publication No. 2015/0091767 ("the' 767 publication") proposes the use of box dipole radiating elements as a technique for stabilizing the azimuth beam width of a lensed multibeam antenna as a function of frequency. U.S. patent publication No. 2018/0131078 ("'078 publication"') describes various additional techniques for stabilizing the azimuth beam width of a lensed multibeam antenna as a function of frequency, including (1) the use of side-by-side radiating elements (i.e., pairs of radiating elements in the horizontal direction), (2) the use of single radiating elements alternating with side-by-side radiating elements, (3) the use of an H-V dipole structure, and (4) the use of a box dipole element having two or more parasitic structures. However, each of these techniques has various potential drawbacks in certain applications. For example, the use of side-by-side radiating elements and/or the use of a single radiating element alternating with side-by-side radiating elements may result in excessive coupling between the side-by-side radiating elements due to the small distance therebetween. This coupling may distort the resulting antenna beam. Likewise, using an H-V dipole structure requires providing each radiating element with a 180 hybrid coupler for conversion to +/-45 polarization. When the operating band is large, such as in the 1.7-2.7GHz band, the box radiating element may be more expensive to manufacture than other commonly used radiating elements and/or may not provide sufficient azimuthal beamwidth stabilization.

According to embodiments of the present invention, lensed base station antennas are provided that may exhibit good azimuth beamwidth stability, even over large operating bands, such as the 1.7-2.7GHz band. These base station antennas comprise a "staggered" vertical array of radiating elements. In this context, a staggered vertical array refers to an array of radiating elements in which the radiating elements are spaced apart from each other in a vertical direction, with at least some of the radiating elements being staggered by a relatively small distance in a horizontal direction relative to other radiating elements. Thus, the staggered vertical arrays extend generally vertically, but the radiating elements are aligned along two or more vertical axes, rather than all along the same vertical axis, as is the case in conventional vertically oriented linear arrays of radiating elements. Each staggered vertical array may have only one radiating element per row, and thus excessive coupling problems that may occur when two radiating elements are provided per row may be avoided, as disclosed in the' 078 publication. Furthermore, the staggering of the radiating elements in the horizontal direction may configure the array to have an azimuth beam width to frequency relationship that is generally opposite to the azimuth beam width to frequency relationship of the RF lens structure, so that the lensed antenna will have good azimuth beam width stability as a function of frequency.

In some embodiments, the lensed base station antenna may comprise a sector split antenna comprising two, three, or even more staggered vertical arrays of radiating elements. In such embodiments, the antenna may comprise: a first array of first radiating elements configured to transmit respective sub-components of a first radio frequency ("RF") signal; a second array of second radiating elements configured to transmit respective sub-components of a second RF signal; and an RF lens structure positioned to receive electromagnetic radiation from a first one of the first radiating elements and from a first one of the second radiating elements. The first subset of the first radiating elements are aligned along a first vertical axis and the second subset of the first radiating elements are aligned along a second vertical axis spaced apart from the first vertical axis. The first and second arrays each include a single radiating element per horizontal row.

In some embodiments, a horizontal distance between the first vertical axis and the second vertical axis is between 0.1 and 0.5 wavelengths of a center frequency of an operating band of the first radiating element. In embodiments where the operating frequency band of the first radiating element is within the 1.7-2.7GHz band, the horizontal distance between the first vertical axis and the second vertical axis may be, for example, between 20-75 mm. In some embodiments, the boresight pointing direction of the first one of the first radiating elements may not intersect a longitudinal axis extending through a center of the RF lens structure.

Reference is now made to fig. 1A, which is a schematic top view of a lensed base station antenna 10. The base station antenna 10 includes a conventional linear array 12 of radiating elements 14 aligned along the same vertical axis (only the top radiating element 14 is visible in fig. 1A). The linear array 12 generates an antenna beam 18 which is injected into a cylindrical RF lens 16 which focuses the antenna beam 18. The RF lens 16 will focus the incident RF signal more as its frequency increases because the focus increases with the number of wavelengths through which the RF signal circulates as it passes through the RF lens 16, and thus the RF lens 16 will focus the higher frequency RF signal passing through the RF lens 16 more than the lower frequency RF signal.

However, the extent to which the RF lens 16 will focus the antenna beam incident thereon is a function not only of the frequency of the RF signal, but also of how much of the RF lens 16 is illuminated by the incident antenna beam. As shown in fig. 1A, if an antenna beam 18 having a relatively wide azimuth beamwidth is injected into the RF lens 16, the antenna beam 18 will illuminate most of the RF lens 16. In contrast, as shown in fig. 1B, if an antenna beam 18 'with a slightly smaller azimuthal beamwidth is injected into the RF lens 16, the antenna beam 18' will illuminate fewer RF lenses 16 and, therefore, will be focused by the RF lenses 16 less than the antenna beam 18, all other things being equal. Thus, if the linear array 12 of radiating elements 14 can be designed to generate an antenna beam having an azimuth beam width that varies with frequency in an opposite manner to the manner in which the RF lens 16 varies the azimuth beam width with frequency, a lensed base station antenna having a relatively stable azimuth beam width with frequency variation can be provided.

For example, the azimuth beamwidth of an antenna beam generated by a two column array of radiating elements will vary with frequency, since the higher the frequency, the greater the horizontal spacing between the two columns, in terms of wavelength. Thus, the beam width in the azimuth plane of the antenna beam generated by the two column array will vary with frequency. The staggered vertical array included in the base station antenna according to embodiments of the present invention operates effectively in the same manner as the two column array described above. In particular, as the distance (in terms of wavelength) between radiating elements positioned along different vertical axes increases with increasing frequency, the azimuthal beamwidth of the antenna beam injected into the RF lens 16 will decrease with increasing frequency. Azimuth beamwidth stability may be achieved if the ratio of the electric field aperture S1 of the antenna beam 18 illuminating the RF lens 16 at a first frequency f1 at the low end of the operating frequency band (e.g., 1.7GHz) to the electric field aperture S2 of the antenna beam 18' illuminating the RF lens 16 at a second frequency f2 at the high end of the operating frequency band (e.g., 2.7GHz) is approximately equal to the ratio of frequency f1 to frequency f 2. Thus, by staggering some of the radiating elements in the horizontal direction, the extent to which the array 12 illuminates the RF lens 16 varies with frequency, thereby cancelling the frequency-dependent effect of the RF lens 16 on the azimuthal beamwidth.

Embodiments of the present invention will now be discussed in more detail with reference to the accompanying drawings, in which exemplary embodiments are shown.

Reference will now be made to fig. 2-4, which illustrate a lensed multi-beam base station antenna 100 with a radome removed, in accordance with some embodiments of the present invention. In particular, fig. 2 is a perspective view of the lensed multi-beam base station antenna 100, while fig. 3 is a perspective view of the lensed multi-beam base station antenna 100 of fig. 2 with the RF lens structure also removed to better illustrate the staggered vertical array of radiating elements included in the antenna 100. Fig. 4 is a cross-sectional view of the lensed multi-beam base station antenna 100. Fig. 13 is a schematic front view of one of the staggered vertical arrays of radiating elements included in antenna 100.

The lensed multi-beam base station antenna 100 includes a generally V-shaped reflector 102 that includes a first reflector panel 104-1 and a second reflector panel 104-2. The reflector panels 104 may each be a substantially planar panel. The reflector 102 may also include a pair of sidewalls 106 extending forward from the outer edges of the respective reflector panels 104. The reflector 102 may also include a dividing wall 108 extending forward from a central portion of the reflector 102.

The lensed multi-beam base station antenna 100 may also include first and second staggered vertical arrays 110-1, 110-2 of radiating elements 120. As described above, a "staggered vertical array" refers to an array of radiating elements in which the radiating elements are spaced apart from one another in a vertical direction, with at least some of the radiating elements being staggered by a relatively small distance in a horizontal direction relative to other radiating elements. As best shown in fig. 3 and 13, the staggered vertical array 110-1 includes a plurality of radiating elements 120 that are vertically spaced apart from one another, and the radiating elements 120 are vertically aligned along two spaced apart vertical axes V1 and V2. Similarly, the staggered vertical array 110-2 includes a plurality of radiating elements 120 that are vertically spaced apart from one another, and the radiating elements 120 are vertically aligned along two other spaced apart vertical axes V3 and V4. Each radiating element 120 in each array 110 is vertically adjacent to one radiating element 120 aligned on the same vertical axis and one radiating element 120 aligned along an adjacent vertical axis, except for the radiating elements 120 at either end of each staggered vertical array 110.

The staggered vertical arrays 110-1, 110-2 may be mounted to extend forward from the respective reflector panels 104-1, 104-2. The reflector panels 104-1, 104-2 may be formed from a unitary piece of metal, or may comprise a plurality of different pieces. As best shown in FIG. 4, the reflector panels 104-1, 104-2 may define a pair of planes that meet at an oblique angle α. In some embodiments, the oblique angle α may be an angle between 100 ° and 140 °. For example, in some embodiments, the oblique angle α may be an angle of about 120 °.

As best shown in fig. 3 and 13, the radiating elements 120 may be mounted on the feed plate 112 such that two (or more) radiating elements 120 have a common feed component. In some embodiments, the feed plate 112 may be mounted in front of the reflector 102. In the depicted embodiment, each staggered vertical array 110 includes a total of fourteen radiating elements 120 (only thirteen of which are visible in fig. 3), and two radiating elements 120 are mounted on each feed plate 112. Since all of the radiating elements 120 are vertically spaced from one another, each staggered vertical array 110 includes a total of fourteen rows, with a single radiating element 120 included in each row, as best seen in fig. 13. As can also be seen in fig. 13, the base station antenna 100 is configured such that a first subset of the feed plates 112 are aligned along a first vertical axis V1 and a second subset of the feed plates 112 are aligned along a second vertical axis V2. As discussed below, other embodiments of the present invention have different feed plate arrangements.

Each radiating element 120 may be, for example, a dual polarization (cross dipole) radiating element including a first dipole radiator angled at-45 ° with respect to a longitudinal (vertical) axis of the antenna 100 and a second dipole radiator angled at +45 ° with respect to the longitudinal axis of the antenna 100. Thus, each interleaved vertical array 110 can simultaneously transmit two RF signals, a first RF signal having a first polarization transmitting through the-45 ° dipole radiator of the radiating element 120 and a second RF signal having a second orthogonal polarization transmitting through the +45 ° dipole radiator of the radiating element 120.

The lensed multi-beam base station antenna 100 may include a plurality of RF ports 150. When the radiating element 120 is implemented as a dual polarization radiating element, two ports 150 may be provided for each staggered vertical array 110 to supply an RF signal at each polarization to each staggered vertical array 110-1, 110-2. Further, radiating element 120 may be a broadband radiating element configured to transmit signals in two or more different frequency bands (e.g., two different frequency bands within the 1.7-2.7GHz frequency range). When using the broadband radiating element 120, duplexing may be performed in the antenna 100 or in a radio device connected to the antenna 100. If duplexing is performed in the radio device, the antenna 100 may have four RF ports 150, i.e., an RF port 150 for each of the two polarizations of each staggered vertical array 110, and RF signals in both frequency bands are passed through each RF port 150. Conversely, if duplexing is performed in the antenna 100, each RF port 150 may only receive RF signals in a single frequency band from the respective attached radio, and thus in this configuration, a total of eight RF ports 150 would be included in the antenna 100.

As described above, each staggered vertical array 110 may transmit a first RF signal and a second RF signal simultaneously. The first RF signal is transmitted through the-45 deg. dipole radiator of the radiating element 120 and the second RF signal is transmitted through the +45 deg. dipole radiator of the radiating element 120. A first RF signal may be input to the antenna 100 through a first one of the RF ports 150, and a first feed network (not shown) may, for example, divide the first RF signal into seven sub-components that are fed to the seven feed plates 112 included in the staggered vertical array 110-1. Each feed plate 112 may include a 1x2 power divider (not shown) for a-45 ° dipole radiator that further subdivides the sub-components of the first RF signal input to the respective feed plate 112. The output of each 1x2 power divider (not shown) for a-45 ° dipole radiator is coupled to a corresponding-45 ° dipole radiator of the two radiating elements 120 mounted on each feed plate 112. Similarly, a second RF signal may be input to the antenna 100 through a second one of the RF ports 150, and a second feed network (not shown) may, for example, divide the second RF signal into seven sub-components that are fed to the seven feed plates 112 included in the interleaved vertical array 110-1. Each feed plate 112 may also include a 1x2 power divider for a +45 ° dipole radiator that further subdivides the sub-components of the second RF signal input to the respective feed plate 112. The output of each 1x2 power divider for a +45 ° dipole radiator is coupled to a corresponding +45 ° dipole radiator of two radiating elements 120 mounted on each feed plate 112.

Although not shown in the figures, the first and second feed networks may each further comprise an electronic or electromechanical phase shifter that applies a phase taper to, for example, the seven subcomponents of the respective first and second RF signals. The phase taper may be adjusted by changing the settings on the respective phase shifters so as to change the downtilt angles of the antenna beams generated by the respective first and second RF signals.

The staggered vertical array 110-2 may be configured the same as the staggered vertical array 110-1, and thus further description thereof will be omitted.

As shown in fig. 2 and 4, the lensed base station antenna 100 also includes an RF lens structure 130. The RF lens structure 130 may include, for example, one or more dielectric RF lenses. In the depicted embodiment, the RF lens structure 130 is implemented using a single vertically extending cylindrical RF lens 130. In an exemplary embodiment, the RF lens structure 130 may be formed of a material having a uniform dielectric constant that focuses RF energy. In other embodiments, the RF lens structure 130 may include a luneberg lens (Luneburg lens) having concentrically arranged layers of dielectric material having varying refractive indices. The RF lens structure 130 may be formed, for example, using any of the lens materials disclosed in U.S. patent publication No. 2017/0279202, which is incorporated herein by reference in its entirety. In some embodiments, the RF lens structure 130 may be a homogeneous lens and may include one or more RF lenses. When the RF lens structure 130 includes a plurality of RF lenses, the RF lenses may be, for example, cylindrical, spherical, or elliptical RF lenses.

Antenna 100 may comprise a dual-beam broadband antenna. In operation, the RF lens structure 130 narrows the HPBW of the antenna beams generated by each of the staggered vertical arrays 110-1, 110-2 and thus increases the gain of these antenna beams. For example, the RF lens structure 130 may reduce the HPBW of the generated antenna beam to about 33 °. The staggered vertical arrays 110 of radiating elements 120 can be configured to inject RF signals at different angles into the RF lens structure 130 to generate side-by-side antenna beams that together can provide coverage for a 120 sector. It should be noted that antennas according to embodiments of the present invention may be used in applications other than sector splitting, for example in venues such as stadiums, general brooks, convention centers, and the like. In such applications, the multi-beam is more typically configured to cover a 60 ° -90 ° sector.

As discussed above, the radiating element 120 may be designed to generate an antenna beam having a relatively stable azimuthal beamwidth over the operating frequency range of the radiating element 120, while the RF lens structure 130 will focus more of the higher frequency RF signals than the lower frequency RF signals in the azimuthal plane. Thus, a lensed base station antenna comprising a conventional linear array of radiating elements may have poor azimuth beamwidth stability, particularly if the antenna is designed to operate over a large frequency range. Due to the use of the staggered vertical arrays 110, the base station antenna 100 may exhibit improved azimuth beamwidth stability because the staggered vertical arrays 110 produce relatively narrow antenna beams at higher frequencies that illuminate only a portion of the RF lens 130, and therefore, are not highly focused by the RF lens structure 130, and therefore more densely focused by the RF lens structure 130, as are antenna beams that illuminate a larger portion of the RF lens produced by the staggered vertical arrays 110 at lower frequencies.

The staggered vertical array 110-1 produces a narrower antenna beam in the azimuth plane, which results in less illumination at the edges of the RF lens structure 130. The illumination taper at the edge of the RF lens structure 130 increases as the azimuth HPBW of the antenna beam injected into the RF lens structure 130 decreases. For example, if a conventional vertical linear array is used in the antenna 100 instead of the staggered vertical array 110, the angle subtended by the RF lens structures 130 may be much smaller than the azimuth HPBW of the conventional vertical linear array. Thus, even though the HPBW of a conventional vertical linear array may narrow as the frequency increases, the taper variation at the edges of the RF lens structure 130 may only increase from, for example, perhaps 0.2dB for the lowest frequency to 0.5dB for the highest frequency in the operating band. However, in the case of including the staggered vertical arrays 110 in an antenna according to embodiments of the present invention, the edges of the RF lens structure 130 are already tapered at the lowest frequencies, and since the shape of the beam pattern roll-off is nominally parabolic, the rate of roll-off increases as the roll-off value increases. Thus, if the roll-off is 2dB at the lowest frequency, it is 5dB at the highest frequency. Since the stability of the azimuth HPBW of the antenna beam exiting the RF lens structure 130 depends on the large variation of the taper on the RF lens structure 130 with increasing frequency, an antenna implemented with an interleaved vertical array will show improved azimuth HBW stability. It should also be noted that although the magnification efficiency (contraction of the azimuthal HPBW) decreases with increasing taper (less efficient use of lenses), at the low end of the band, including the interleaving means that the starting azimuthal HPBW (before the lenses) is already narrower, so the end result is that even at some taper the azimuthal HPBW after the RF lens structure is still narrower than without interleaving. With sufficiently wide interleaving, the azimuth HPBW after the lens can be made almost constant over a fairly wide band with respect to frequency. At some point, however, the staggering becomes large enough so that the right "column" of the left staggered vertical array 110 can begin to couple to the left "column" of the right staggered vertical array 110.

Thus, although the RF lens will largely focus more high frequency RF signals than low frequency RF signals, since the base station antenna 100 is designed such that the antenna beam generated by the high frequency RF signals is smaller than the portion of the RF lens structure 130 illuminated by the antenna beam generated by the low frequency RF signals, the RF lens structure 130 will perform less focusing of the antenna beam generated by the high frequency RF signals, since the RF lens structure 130 is actually a smaller RF lens for this RF signal. Thus, the overall effect of the RF lens structure 130 may be relatively independent of frequency, providing improved azimuthal beamwidth stability.

Fig. 5A-5C are a series of graphs illustrating the improvement in azimuth beamwidth stability that can be achieved by using staggered elevation arrays according to embodiments of the present invention instead of conventional linear arrays in sector-split lensed base station antennas. In particular, fig. 5A-5C illustrate improvements in 3dB, 10dB, and 12dB azimuth beamwidth stability that may be achieved in exemplary embodiments through the use of staggered vertical arrays. Improved azimuth beamwidth stability provides better crossover performance.

Referring first to fig. 5A, the graph on the left side of fig. 5A shows the measured 3dB azimuth beamwidth as a function of frequency for a lensed base station antenna 200, which is a modified version of the lensed base station antenna 100 including a conventional linear array 210, over the frequency range of 1.7-2.7 GHz. Fig. 6 is a schematic perspective view of the antenna 200 with the radome and RF lens removed, showing a conventional linear array 210 included therein. As shown in the graph on the left side of FIG. 5A, the measured 3dB azimuth beamwidth for antenna 200 including the conventional linear array design varies from 26-41 in the 1.7-2.7GHz range, with an azimuth beamwidth in the 8.6 range for 84% of the frequency range. The graph on the right side of fig. 5A shows the measured 3dB azimuth beamwidth as a function of frequency for the lensed base station antenna 100 according to an embodiment of the present invention over the frequency range of 1.7-2.7 GHz. As shown in the right graph of FIG. 5A, the measured 3dB azimuth beam width for the lensed base station antenna 100 according to embodiments of the present invention varies from 26-38 in the 1.7-2.7GHz range, with an azimuth beam width of 84% of the frequency range in the 6.0 range, or 30% improvement.

Referring next to FIG. 5B, the left graph shows the 10dB azimuth beam width as a function of frequency measured over the 1.7-2.7GHz frequency range for antenna 200, while the right graph shows the 10dB azimuth beam width as a function of frequency measured over the 1.7-2.7GHz frequency range for lensed base station antenna 100 according to an embodiment of the present invention. As shown in the graph on the left side of FIG. 5B, the 10dB azimuth beamwidth measured for antenna 200 including the conventional linear array design varies from 44-73 in the 1.7-2.7GHz range, with an azimuth beamwidth of 84% of the frequency range in the 17 range. In contrast, as shown in the graph on the right side of FIG. 5B, the 10dB azimuth beam width measured for the lensed base station antenna 100 according to embodiments of the present invention varies from 48-68 in the 1.7-2.7GHz range, with an azimuth beam width of 84% of the frequency range being in the 11 range, or improved by 35%.

Referring next to fig. 5C, the left graph shows the 12dB azimuth beam width as a function of frequency measured over the 1.7-2.7GHz frequency range for antenna 200, while the right graph shows the 12dB azimuth beam width as a function of frequency measured over the 1.7-2.7GHz frequency range for lensed base station antenna 100 according to an embodiment of the present invention. As shown in the graph on the left side of FIG. 5C, the 12dB azimuth beamwidth measured for antenna 200 including the conventional linear array design varies from 47-84 in the 1.7-2.7GHz range, with the azimuth beamwidth for the 84% frequency range being in the 23 range. In contrast, as shown in the graph on the right side of FIG. 5C, the 12dB azimuth beam width measured for the lensed base station antenna 100 according to embodiments of the present invention varies from 53-75 in the 1.7-2.7GHz range, with an azimuth beam width of 84% of the frequency range being in the 12 range, or an improvement of 48%.

Referring again to fig. 13, the vertical axes V1, V2 are spaced apart by a horizontal distance H1. The vertical axes V3, V4 will also typically be spaced apart by the same horizontal distance H1 as the vertical axes V1, V2. In the base station antenna 100 for generating the patterns shown in fig. 5A to 5C, the horizontal distance H1 is set to 45 mm. In a base station antenna operating in the frequency range of 1.7-2.7GHz in accordance with an embodiment of the invention, the horizontal distance H1 may be, for example, 20-75 mm. It will be appreciated that the horizontal distance H1 by which the vertical axes V1, V2 are spaced apart will vary as the operating frequency of the radiating element 120 varies. Thus, in an exemplary embodiment of the invention, the horizontal distance H1 (i.e., the spacing between the vertical axes V1, V2) may be between 0.1 and 0.5 wavelengths of the center frequency of the operating band of the radiating element 120. In other embodiments, the horizontal distance H may be between 0.1 and 0.35 wavelengths of the center frequency of the operating band of the radiating element 120.

Typically, the radiating elements in a lensed base station antenna are oriented such that the boresight pointing direction of the radiating element (which refers to the axis along which peak RF energy is emitted, which is typically the axis extending from the center of the crossed dipole radiating element in a direction perpendicular to the plane defined by the crossed dipole) extends through a vertical axis extending through the center of the RF lens. However, the base station antenna 100 includes a substantially planar reflector panel 104 for each staggered vertical array 110. Since the radiating elements 120 are staggered in the horizontal direction, the boresight pointing directions of all the radiating elements 120 cannot point to a longitudinal axis passing vertically through the center of the RF lens 130.

As shown in fig. 4, in the base station antenna 100, the radiation element 120 aligned along the vertical axis V1 may be directed slightly to the right of the vertical axis L extending through the center of the RF lens 130, and the radiation element 120 aligned along the vertical axis V2 may be directed slightly to the left of the vertical axis L. Thus, the peak radiation emitted by the staggered vertical array 110-1 may not be directed toward the vertical axis L extending through the center of the RF lens 130, and thus the resulting antenna beam has two peaks (in azimuth plane) offset to either side of the vertical axis L. Fig. 7 is a schematic diagram of an azimuthal cut of the antenna beams generated by the staggered vertical array 110-1 (after radiation passes through the RF lens 130). As can be seen in fig. 7, two peaks exist in the bitmap, one on either side of the center of the sub-sector. This results in a broad spike, which may be desirable in certain applications.

Fig. 8 is a schematic cross-sectional view of a modified version 100' of the lensed multi-beam base station antenna 100 configured such that the boresight pointing direction of each radiating element 120 passes through a vertical axis L extending through the center of the RF lens 130. As shown in fig. 8, this may be achieved by replacing the reflector 102 of the base station antenna 100 with the reflector 102' shown in fig. 8. As can be seen in fig. 8, the reflector 102' has a total of four reflector panels 105-1 to 105-4. Each reflector panel 105 is positioned such that the boresight pointing direction of the radiating element 120 mounted thereon will pass through the longitudinal axis L of the RF lens 130. This design will result in a more conventional antenna beam shape.

Fig. 9 is a schematic illustration of a lensed base station antenna 200 according to an embodiment of the invention (with the radome and RF lens structures omitted). The lensed base station antenna 200 includes a staggered vertical array based on individual radiating elements rather than feed plate staggering. As shown in fig. 9, the lensed base station antenna 200 may be nearly identical to the lensed base station antenna 100, except that in the base station antenna 200, each radiating element 120 is mounted on a single feed plate, while in the base station antenna 100, two radiating elements 120 are mounted on each feed plate 112.

Fig. 10 schematically illustrates another lensed base station antenna 300 in accordance with an embodiment of the present invention. In fig. 10, the RF lens structure (which may be the same as the RF lens structure 130 shown in fig. 2 and 4) and the radome are removed to illustrate the two staggered vertical arrays 310-1, 310-2 included in the antenna 300. As shown in fig. 10, the staggered vertical array 310-1 includes radiating elements 120 aligned along two spaced vertical axes V1, V2, and the staggered vertical array 310-2 includes radiating elements 120 aligned along two spaced vertical axes V3, V4. The antenna 300 comprises a feed plate 312 that is extended in length and rotated 45 deg. compared to the feed plate 112 of the lensed base station antenna 100. Thus, each feed plate 312 in the staggered vertical array 310-1 includes a first radiating element 120 aligned along vertical axis V1 and a second radiating element 120 aligned along vertical axis V2. Similarly, each feed plate 312 in the staggered vertical array 310-2 includes a first radiating element 120 aligned along vertical axis V3 and a second radiating element 120 aligned along vertical axis V4.

Fig. 11 is a schematic illustration of a base station antenna 400 according to yet other embodiments of the present invention comprising a staggered vertical array 410 of radiating elements 120 positioning the radiating elements 120 along three different vertical axes. It can be seen that the base station antenna 400 may be very similar to the base station antenna 200, except that the radiating elements 120 are aligned along three different vertical axes instead of two different vertical axes. It should be appreciated that the radiating elements 120 may be aligned along any number of vertical axes.

The base station antenna 100 of fig. 2-4 includes a cylindrical RF lens 130 that extends the entire length of the antenna 100. However, it should be appreciated that a wide variety of different RF lenses may be used. For example, fig. 12 is a schematic perspective view of a lensed base station antenna 500 including an array of elliptical RF lenses 530, according to some embodiments of the invention.

As shown in fig. 12, the base station antenna 500 includes a total of seven elliptical RF lenses 530. Typically, each staggered vertical array 510 included in the base station antenna 500 will have a single radiating element 120 mounted behind each elliptical RF lens 530, and thus the base station antenna 500 will include seven radiating elements 120 in each array 510 as compared to the fourteen radiating elements 120 in the other embodiments described above. Although an elliptical RF lens 530 is shown in fig. 12, it should be understood that a spherical RF lens may be used in other embodiments.

The base station antenna may generate grating lobes, which refer to side lobes formed at high elevation angles. The performance of a base station antenna may be severely degraded if grating lobes are present, since grating lobes represent a power penalty and may increase interference to neighboring sectors or base stations. When the spacing between adjacent radiating elements in a linear array is too large, the grating lobes tend to increase in magnitude. Thus, in conventional linear arrays, adjacent radiating elements are typically spaced less than one wavelength apart in order to suppress grating lobes.

The base station antenna according to an embodiment of the present invention includes interleaving in the horizontal direction. Thus, the distance D3 between a radiating element 120 in the first column (i.e., a radiating element aligned along the vertical axis V1) and an "adjacent" radiating element 120 in the second column (i.e., a radiating element aligned along the vertical axis V2) includes both a horizontal component and a vertical component. To suppress grating lobes, base station antennas according to some embodiments of the present invention may reduce the vertical spacing between adjacent radiating elements located in different columns. For example, as best shown in fig. 13, the radiating elements 120 mounted on the same feed plate 112 may be vertically spaced apart from each other by a first distance D1. Two adjacent radiating elements 120 located in different columns may be vertically spaced from each other by a second distance D2 that may be less than distance D1. In some embodiments, the distance D3 shown in fig. 13 may be approximately equal to the distance D1.

According to further embodiments of the present invention, RF lens end caps are provided that may be used to mount an RF lens within a base station antenna. As discussed above, RF lenses having cylindrical shapes are used in multiple base station antenna designs. In many cases, the RF lens may extend the entire length of the base station antenna, and thus may be large and relatively heavy. Accordingly, fairly wide support structures are commonly used to mount cylindrical RF lenses within base station antennas.

Fig. 14A-14D illustrate a conventional method for supporting a cylindrical RF lens within the housing of a base station antenna. As shown in fig. 14A-14B, a conventional base station antenna 600 includes a cylindrical RF lens 630 that extends the entire length of the antenna 600. A plurality of lens bearings 660 are provided that physically support and position the RF lens 630 within the base station antenna 600. The supports 660 are spaced apart from each other in the vertical direction (i.e., along the longitudinal axis of the base station antenna 600), and a large number of supports 660 may be required (eight supports 660 are used in the base station antenna 600). As best seen with reference to fig. 14B and 14D, each lens support 660 includes a first support 662 and a second support 664, and thus a total of sixteen supports 662, 664 are included in the base station antenna 600 to support the RF lens 630. As shown in fig. 14A and 14C, the lens holder 660 is installed to extend forward from the frame of the base station antenna 600. Specifically, the lens support 660 is mounted to and extends forward from the reflector 602. The lens support 660 spaces the RF lens 630 from the radiating elements of the base station antenna 600 and maintains the RF lens 630 at an appropriate distance from the radiating elements.

In many cases, an RF lens can be formed by filling a dielectric lens housing with one or more RF energy focusing materials designed to focus RF energy. The lens housing may comprise, for example, a plastic or other dielectric container, and the RF energy focusing material may comprise, for example, a slug of RF energy focusing material (which may facilitate randomly orienting the conductive material that may be included in the slug) or a dielectric material in semi-solid (or even liquid) form. According to further embodiments of the present invention, lensed base station antennas are provided having an RF lens that includes a lens housing with integrated mounting features that may eliminate the need for a separate support, such as lens support 660 discussed above.

In particular, according to an embodiment of the present invention, a lensed base station antenna is provided having a lens housing that includes a pair of lens end caps and a body. The body of the lens housing may comprise a thin cylindrical structure open on both ends, and the lens end caps may cover the respective open ends of the body. The body of the lens housing may be formed of, for example, fiberglass or another rigid material. Each lens end cap may include an integrated mounting feature configured to mount on a reflector of a base station antenna or another portion of a frame of the antenna. Because the body of the lens housing is rigid, the body can be stably mounted in place within the antenna using only a pair of mounting features, as opposed to the multitude of mounting features used in at least some conventional lensed base station antennas. Furthermore, in some embodiments, the mounting features may be integrated directly into the lens end cap, such that additional RF lens mounting components may not be required in the base station antenna.

Fig. 15A-15B are internal and external views, respectively, of an RF lens end cap 770, according to an embodiment of the invention. Fig. 15C is a cross-sectional view of a portion of an RF lens housing 762 including the lens end cap of fig. 15A-15B.

Referring to fig. 15A-15C, it can be seen that the lens end cap 770 includes a disk-like structure having a circular central region 772. As shown in fig. 15B, the inside of the lens end cap (i.e., the top side of the bottom end cap and the bottom side of the top end cap) may have a plurality of support ribs 774A, 774B that may increase the strength and stiffness of the lens end cap 770. In the depicted embodiment, radial support ribs 774A are provided as well as circular support ribs 774B. While in the depicted embodiment, the support ribs 774A, 774B are disposed on the inner surface of the lens end cap 770, it should be appreciated that in other embodiments, the support ribs 774A, 774B may alternatively be disposed on the outer surface of the lens end cap 770, on both the inner and outer surfaces of the lens end cap 770, or may be omitted.

The lens end cap 770 also includes a pair of rearwardly extending flanges 776 extending from generally opposite side surfaces of the circular central region 772. The flanges 776 may also each include a support rib 778. In the depicted embodiment, each flange 776 includes support ribs 778 on both sides thereof to provide enhanced strength and rigidity, although other configurations are possible depending on the particular needs. Each flange 776 may further include a mounting point 780, such as a boss, that includes a reinforced region with a central opening (not visible in the drawings) in the flange 776. For example, mounting point 780 may be designed to receive the shaft of a bolt so that lens end cap 770 may be bolted to another structure of the base station antenna, e.g., a reflector.

Referring to fig. 15C, it can be seen that the outer two of the circular support ribs 774B are taller than the other support ribs 774B and form a circular channel 782 that receives the body 764 of the lens housing 762.

Fig. 16A-16C are various views illustrating the manner in which two of the lens end caps 770 of fig. 15A-15C may be used to mount an RF lens 760 having a lens end cap 770 in accordance with an embodiment of the present invention within a base station antenna 700. Fig. 16A is a perspective view of RF lens 760. As shown in fig. 16A, the RF lens 760 includes a lens housing 762 that includes a body 764 and a pair of lens end caps 770. The body 764 may be formed, for example, as an open ended fiberglass cylinder formed by pultrusion. While fiberglass may be a particularly good material for the body 764 of the lens housing 762 due to its strength, stiffness, material cost, ease of manufacture, and RF properties, it should be understood that other materials may be used to form the body 764 of the lens housing 762, such as a variety of different plastics. The lens end cap 770, described in detail above with reference to fig. 15A-15C, may be formed from a polymeric material (e.g., ABS, etc.). The end cap 770 may be formed by, for example, injection molding. The lens housing 762 may be filled with an RF energy focusing material. For example, any of the RF energy focusing materials disclosed in U.S. patent application serial No. 15/882,505 filed on 29/1/2018, the entire contents of which are incorporated herein by reference, may be used as the RF energy focusing material deposited in the lens housing 762 to form the RF lens 760.

As shown in fig. 16B, the lens housing 762 may be mounted on, for example, the reflector 702 of the base station antenna 700 or some other portion of the frame of the antenna. In particular, a hole may be formed in the reflector 702 adjacent each mounting point 780 on the flange 776 of each lens end cap 770. Bolts (not visible in the figures) may pass through holes in the reflector 702 and through openings in the respective mounting points 780, and nuts may be screwed onto the bolts to attach the lens end cap 770 to the reflector 702, and thus to securely fix either end of the RF lens 760 to the reflector 702. The rigidity of the body 764 may ensure that the central portion of the RF lens 760 remains in place within the base station antenna 700.

It will be appreciated that this specification describes only a few exemplary embodiments of the invention, and that the techniques described herein have applicability beyond the exemplary embodiments described above. For example, while the exemplary embodiments described above focus on base station antennas that transmit and receive signals in the 1.7-2.7GHz frequency range, it will be appreciated that staggered vertical arrays may be used in other operating frequency bands. Indeed, the invention may be particularly suitable for higher frequency bands, such as in the 3-6GHz range, since the size of the radiating elements and RF lens is reduced at higher frequencies, and therefore lensed base station antennas may be particularly well suited for use in such frequency bands.

As another example, although the example embodiments described above are suitable for implementing a six sector base station using three base station antennas, it should be appreciated that additional staggered vertical arrays may be included to implement a nine sector or twelve sector base station using, for example, three base station antennas. Thus, for example, while the various appended claims refer to lensed base station antennas comprising a first staggered vertical array and a second staggered vertical array, it should be understood that this means that these antennas comprise at least two staggered vertical arrays, as three or even more staggered vertical arrays would be suitable for various applications. It should also be appreciated that while the above-described embodiment uses-45/+ 45 cross dipole radiating elements, any suitable radiating elements may be used. In addition, each staggered vertical array may have a single associated RF lens or multiple associated RF lenses (e.g., an RF lens for each radiating element of the array, an RF lens for each pair of radiating elements in the array, etc.).

Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between … …" versus "directly between … …", "adjacent" versus "directly adjacent", etc.).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.

The aspects and elements of all embodiments disclosed above may be combined in any manner and/or with aspects or elements of other embodiments to provide multiple additional embodiments.