阅读说明：本技术 用于隔离双极化天线中的正交信号路径并产生附加谐振的寄生元件 (Parasitic element for isolating orthogonal signal paths and creating additional resonance in dual-polarized antennas ) 是由 P·C·T·宋 D·E·巴克 于 2019-07-30 设计创作，主要内容包括：一种天线系统可包括在相同侧向平面中具有第一偶极和第二偶极的双极化天线元件,第一偶极具有第一偶极臂和第二偶极臂,第二偶极包括第三偶极臂和第四偶极臂,第一偶极与第二偶极位于同一位置,并且第一偶极具有与第二偶极正交的极化。该天线系统可进一步包括寄生元件,每个寄生元件包括至少两个分支,该至少两个分支包括以一定角度定向并形成顶点的第一分支和第二分支。第一寄生元件的第一分支可平行于第一偶极的第一偶极臂定位在第一耦合距离处,并且第二分支可平行于第二偶极的第三偶极臂定位在第二耦合距离处。(An antenna system may include a dual polarized antenna element having a first dipole with a first dipole arm and a second dipole including a third dipole arm and a fourth dipole arm in the same lateral plane, the first dipole co-located with the second dipole, and the first dipole having a polarization orthogonal to the second dipole. The antenna system may further include parasitic elements, each parasitic element including at least two branches including a first branch and a second branch oriented at an angle and forming a vertex. The first branch of the first parasitic element may be positioned parallel to the first dipole arm of the first dipole at a first coupling distance and the second branch may be positioned parallel to the third dipole arm of the second dipole at a second coupling distance.)

1. An antenna system, comprising:

at least one dual polarized antenna element comprising a first dipole and a second dipole in the same lateral plane, the first dipole comprising a first dipole arm and a second dipole arm, the second dipole comprising a third dipole arm and a fourth dipole arm, the first dipole co-located with the second dipole, and the first dipole having a polarization orthogonal to the second dipole; and

a plurality of parasitic elements, each parasitic element comprising at least two branches including a first branch and a second branch oriented at an angle and forming a vertex;

wherein a first branch of a first parasitic element of the plurality of parasitic elements is positioned at a first coupling distance and is parallel to a first dipole arm of the first dipole;

wherein the second branch of the first parasitic element is positioned at a second coupling distance and parallel to the third dipole arm of the second dipole.

2. The antenna system of claim 1, wherein the first coupling distance and the second coupling distance are equal.

3. The antenna system of claim 1, wherein the first branch of the second parasitic element of the plurality of parasitic elements is positioned at a third coupling distance and parallel to the first dipole arm of the first dipole; and is

Wherein the second branch of the second parasitic element is positioned at a fourth coupling distance and parallel to a fourth dipole arm of the second dipole.

4. The antenna system of claim 3, wherein the third coupling distance and the fourth coupling distance are equal.

5. The antenna system of claim 4, wherein the first coupling distance, the second coupling distance, the third coupling distance, and the fourth coupling distance are equal.

6. The antenna system of claim 3, wherein the first branch of a third parasitic element of the plurality of parasitic elements is positioned at a fifth coupling distance and parallel to the fourth dipole arm of the second dipole;

wherein the second branch of the third parasitic element is positioned at a sixth coupling distance and is parallel to the second dipole arm of the first dipole;

wherein a first branch of a fourth parasitic element of the plurality of parasitic elements is positioned at a seventh coupling distance and is parallel to a second dipole arm of the first dipole;

wherein the second branch of the fourth parasitic element is positioned at an eighth coupling distance and parallel to the third dipole arm of the second dipole.

7. The antenna system of claim 6, wherein the fifth coupling distance and the sixth coupling distance are equal.

8. The antenna system of claim 6, wherein the sixth coupling distance and the seventh coupling distance are equal.

9. The antenna system of claim 6, wherein the fifth coupling distance, the sixth coupling distance, the seventh coupling distance, and the eighth coupling distance are equal.

10. The antenna system of claim 9, wherein the first coupling distance, the second coupling distance, the third coupling distance, the fourth coupling distance, the fifth coupling distance, the sixth coupling distance, the seventh coupling distance, and the eighth coupling distance are equal.

11. The antenna system of claim 1, wherein at least one parasitic element of the plurality of parasitic elements has a third branch joined at the vertex, and the third branch is oriented at 45 degrees in the same plane relative to the first branch and the second branch of the at least one parasitic element.

12. The antenna system of claim 1, wherein the lengths of the at least two branches are equal for each parasitic element of the plurality of parasitic elements.

13. The antenna system of claim 12, wherein the at least two branches of each parasitic element of the plurality of parasitic elements are equal in length among the plurality of parasitic elements.

14. The antenna system of claim 1, wherein the plurality of parasitic elements are located in the same lateral plane as the first dipole and the second dipole.

15. The antenna system of claim 1, wherein the plurality of parasitic elements are located in different planes with respect to the first dipole and the second dipole.

16. The antenna system of claim 1, wherein the parasitic coupling structure comprising a square patch is located in a plane above an intersection of the first dipole and the second dipole.

17. A parasitic element comprising at least two branches, the at least two branches comprising a first branch and a second branch oriented at an angle and forming a vertex;

wherein the parasitic element is for deployment as one of a plurality of parasitic elements of at least one dual polarized antenna element comprising a first dipole and a second dipole in the same lateral plane, the first dipole comprising a first dipole arm and a second dipole arm, the second dipole comprising a third dipole arm and a fourth dipole arm, the first dipole co-located with the second dipole, and the first dipole and the second dipole orthogonally polarized;

wherein the first branch of the parasitic element is for positioning at a first coupling distance and parallel to a first dipole arm of the first dipole;

wherein a second branch of the parasitic element is for positioning at a second coupling distance and parallel to a third dipole arm of the second dipole.

18. The parasitic element of claim 17 wherein said first coupling distance and said second coupling distance are equal.

19. The parasitic element of claim 17 wherein the length of said first branch and the length of said second branch are equal.

20. The parasitic element of claim 17 wherein said at least two branches include a third branch joined at an apex, and said third branch is oriented at 45 degrees in the same plane relative to said first branch and said second branch of said at least one parasitic element.

Technical Field

The present disclosure relates generally to communication antenna systems and more particularly to dual polarized antenna elements and antenna arrays having parasitic elements with improved port-to-port isolation and widened impedance bandwidth.

Background

Additional spectrum bands have been released in recent years and cellular operators have been deploying new radio access technologies to meet subscriber traffic demands. The antenna system at the base station site may support multiple frequency bands operating over very large bandwidths (e.g., 617-. The antenna system may also preferably have desired radiation characteristics and diversity performance with good port-to-port isolation. Dual polarized antenna elements with two independent RF ports on the same antenna structure are widely used in mobile communications because the two orthogonal polarized elements are co-located without space loss and also provide a means of polarization diversity for the radio.

Disclosure of Invention

In one example, the present disclosure describes an antenna system comprising at least one dual-polarized antenna element comprising first and second dipoles in a same lateral plane, the first dipole comprising first and second dipole arms, the second dipole comprising third and fourth dipole arms, the first and second dipoles being co-located and the first dipole having a polarization orthogonal to the second dipole. The antenna system may further include a plurality of parasitic elements, each parasitic element including at least two branches including a first branch and a second branch oriented at an angle and forming a vertex. In one example, the first branch of a first parasitic element of the plurality of parasitic elements is positioned at the first coupling distance and parallel to the first dipole arm of the first dipole. In addition, the second branch of the first parasitic element may be positioned at the second coupling distance and parallel to the third dipole arm of the second dipole.

In one example, the present disclosure also describes a parasitic element comprising at least two branches including a first branch and a second branch oriented at an angle and forming a vertex. In one example, the parasitic element is for deployment as one of a plurality of parasitic elements of at least one dual polarized antenna element, the at least one dual polarized antenna element comprising a first dipole and a second dipole in a same lateral plane, the first dipole comprising a first dipole arm and a second dipole arm, the second dipole comprising a third dipole arm and a fourth dipole arm, the first dipole co-located with the second dipole, and the first dipole orthogonally polarized with the second dipole. In one example, a first branch of the parasitic element is for being positioned at a first coupling distance and parallel to a first dipole arm of the first dipole, and a second branch of the parasitic element is for being positioned at a second coupling distance and parallel to a third dipole arm of the second dipole.

Drawings

The teachings of the present disclosure can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:

fig. 1 depicts a base station antenna having a triple array configuration;

fig. 2A to 2D show examples of dipole antennas or antenna elements;

figures 3A to 3D show examples of dual polarized antenna elements with "V" shaped parasitic elements according to the present disclosure;

figures 4A-4D illustrate a three-branch parasitic element and an antenna or antenna element including such a three-branch parasitic element according to the present disclosure;

fig. 5 illustrates an antenna array with dual polarized antenna elements for operation in a Low Band (LB) of Radio Frequency (RF) frequencies integrated with parasitic elements in accordance with the present disclosure;

to facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.

Detailed Description

Examples of the present disclosure describe a technique to improve port-to-port isolation and widen the impedance bandwidth of dual polarized antenna elements, such as crossed dipole antenna elements. Parasitic elements are added between the radiating elements (e.g., driven dipoles) of a dual-polarized antenna element to provide quadrature Radio Frequency (RF) current cancellation. This results in improved isolation across the large bandwidth of the dual polarized antenna element. At the same time, the parasitic element also creates an additional resonant mode that couples into the main radiating element to widen the operating bandwidth.

As used herein, the terms "antenna" and "antenna array" are used interchangeably. To remain consistent, and unless specifically stated otherwise, for any of the depicted antenna arrays, the actual horizontal line is indicated on the page as left-to-right/right-to-left, while the up/vertical direction is the direction from the bottom of the page to the top of the page, consistent with the text/numbers of the figure.

It should also be noted that although the terms "first," "second," "third," etc. may be used herein, these terms are intended only as labels. Thus, use of a term such as "third" in one example does not necessarily mean that the example must include "first" and/or "second" of similar items in each instance. In other words, the use of the terms "first," "second," "third," and "fourth" do not imply a particular number of those items corresponding to those numerical values. In addition, unless otherwise indicated, use of the term "third," for example, does not imply a particular order or temporal relationship of "first" and/or "second" with respect to a particular type of item.

Additional spectrum bands have been released in recent years and cellular operators have been deploying new radio access technologies to meet subscriber traffic demands. The antenna system at the base station site may support multiple frequency bands operating over very large bandwidths (e.g., 617-. The antenna system may also preferably have desired radiation characteristics and diversity performance, and have good port-to-port isolation. Dual polarized antenna elements with two independent RF ports on the same antenna structure are widely used in mobile communications because the two orthogonal polarized elements are co-located without space loss and also provide a means of polarization diversity for the radio.

Fig. 1 depicts a triple array configuration with a base station antenna 100 comprising a series of N unit cells 110₁To 110_NWhich is configured to form three dual-polarized antenna arrays 106,107 and 108 located above the reflector 102. First dual-polarized antenna array 106 is designed for operation in the LB range of RF frequencies, while second dual-polarized antenna array 107 and third dual-polarized antenna array 108 are designed for operation in the HB range of RF frequencies. Each cell comprises a larger LB dual polarized antenna element 101 for LB dual polarized antenna array 106, two HB dual polarized antenna elements (each element 103) for first HB dual polarized antenna array 107, and two HB dual polarized antenna elements (each element 104) for second HB dual polarized antenna array 108. The vertical distance or pitch between the HB dual polarized antenna elements is typically half the pitch of the LB dual polarized antenna elements 101. In this triple dual-polarized column antenna array, an LB dual-polarized antenna array 106 is typically located in the center of reflector 102. This configuration is also commonly referred to as a "side-by-side" base station antenna configuration.

LB dual polarized antenna element 101 may include radiating elements 101A such as dipoles with a +45 degree oblique polarization and orthogonally polarized radiating elements 101B with a-45 degree oblique polarization. LB dual polarized antenna element 110₁-110_NAre distributed along the length of the reflector 102 at predetermined spacings adjusted to optimize the directivity, elevation radiation main beam tilt range, and elevation radiation pattern sidelobe performance. Each dual-polarized antenna element 103 of the first HB dual-polarized antenna array 107 further comprises +45 degree polarization and-45 degree polarized radiating elements 103A and 103B. Each dual-polarized antenna element 104 of second HB dual-polarized antenna array 108 also includes +45 degree polarized and-45 degree polarized radiating elements 104A and 104B, respectively. Due to this arrangement, the reflector width of the antenna can be widened to accommodate all of these elements. However, additional mutual coupling effects may still occur in the vicinity of the elements, resulting in a destruction of the radiation pattern, a deterioration of the port-to-port isolation and a reduction of the impedance bandwidth.

As shown in fig. 2A, a first dipole 203 (or "dipole antenna") may include pairs of quarter-wave conductors 201A and 201B connected via a feed port 202 to drive Radio Frequency (RF) power into the dipole 203 for radiation. This arrangement gives the resonant dipole 203 an operating frequency F₁Of half the wavelength (lambda/2). To create a dual polarization or diversity dipole pair as shown in fig. 2B, second dipole 205 having feed port 204 is placed orthogonal to first dipole 203 with both feed ports 202 and 204 for first dipole 203 and second dipoles and 205 located at the same location.

In addition, because the physical length of each dipole 203 and 205 creates a single current path (e.g., current path 207 as shown in fig. 2A), each dipole only operates at a single frequency F₁And (4) upper resonance. Several techniques can be used to enhance the bandwidth of the single dipole, such as increasing the size of the guide region into the pair of square radiators 206A and 206B as shown in fig. 2C, or generating additional resonances in both cases by using parasitic elements 208 as shown in fig. 2D. The antenna shown in fig. 2C is also referred to as a "bowtie" antenna and has two current paths that are excited. The first path 207A has a resonant frequency F₁And the second path 207B results in a second resonant frequency F along the edge of the conductor₂. In fig. 2D, parasitic elements 208 having different conductor lengths cause a second resonant frequency F when placed close to dipole 203 (via current path 207B)₂. The result of the parasitically coupled second resonance is an increase in the bandwidth of the dipole/radiating element.

Dual polarized antenna elements may be designed for optimal (i.e., low to zero) cross polarized components of radiation or for optimal (i.e., large) bandwidth. These two design goals often conflict with each other. A broadband dual polarized antenna element using a bowtie dipole may produce a large cross-polarized component of radiation, while a dual polarized antenna element using a dipole may provide a smaller cross-polarized component of radiation, but still remain relatively narrow-band. This is because the physical dimensions of the feed and dipole/radiating element do not scale with frequency and do not provide consistent optimal radiation behavior.

To achieve good port-to-port isolation and improved cross-polarization levels while maintaining a wider bandwidth, antenna designs may use aperture coupling feeds or feed capacitive coupling methods to minimize parasitic inductive effects of the antenna transmission probe (e.g., parasitic coupling via a soldered bond or the like to a physical feed line of the radiating element or without physical contact) to provide a greater bandwidth. In another example, multiple feed ports may be used to drive the same antenna elements in anti-phase to cancel parasitic current amplitudes that cause radiated cross-polarized power. Reducing the number of feed ports and the complexity of the feed network can improve port-to-port isolation. However, specific phasing techniques may be required to ensure that all elements radiate coherently.

Examples of the present disclosure enhance the impedance bandwidth of a single resonant dipole (or dipole antenna) and also generate orthogonal current paths that allow vector cancellation of cross-polarized power in a dual-polarized antenna element deployment, providing improved radiation pattern performance, port-to-port isolation (e.g., between RF ports feeding orthogonally polarized radiating elements of a dual-polarized antenna element and/or antenna array), and simplified implementation without the complexity of multiple feeds.

Fig. 3A shows an example with a dual polarized antenna element 301 comprising two orthogonally polarized (and orthogonally oriented) juxtaposed dipoles 203 and 205 (or "radiating elements"), with half wavelength current paths represented by 303 and 307, respectively. In fig. 3B, four "V" -shaped right-angle parasitic elements 302A,302B,302C,302D are located around dual-polarized antenna element 301. These parasitic elements 302A,302B,302C,302D are placed at equal distances 304 from member dipoles 203 and 205. In other words, the parasitic elements 302A,302B,302C,302D are distributed in a symmetrical manner around an imaginary center of the dual-polarized antenna element 301.

Fig. 3C shows the current distribution of dual polarized antenna element 301 and illustrates the additional resonance introduced by the parasitic elements configured as in fig. 3B. As previously described in connection with fig. 2A, dipole 203 is at frequency F due to current path 303₁At resonance. From the vicinity of parasitic elements 302A and 302D, a current path 305 is induced in the opposite direction of current path 303. Similarly, for the parasitic elements 302B and 302C, a current path 306 in the opposite direction to the main current path 303 is also induced. The electrical length of current paths 305 and 306 on dipole 203 (e.g., driven dipole/radiating element) may result in a second resonance F₂This second resonance will widen the bandwidth of the dual polarized antenna element 301. The current paths of 305 and 306 are typically shorter than the current path of 303, which means that F₂Typically ratio of F₁With higher frequencies.

Fig. 3D illustrates the current cancellation effect of parasitic elements 302A,302B,302C, and 302D to improve port-to-port isolation. Similar to the depiction of fig. 3C, where dipole 203 is excited by current path 303, current path 305 on parasitic element 302A also induces current path 305A due to the continuity of current over the physical length of parasitic element 302A. Similarly, current path 305 on 302D also induces current 305B due to the continuity of the current on parasitic element 302D. Note that the current vectors of 305A and 305B are in opposite directions. In the same manner, current path 303 also induces current path 306 on parasitic elements 302B and 302C. Current paths 306A and 306B are also created due to the continuity of the current over the physical length of parasitic elements 302B and 302C. Note that the current vectors of 306A and 306B are also in opposite directions. This means that the current vectors generated from dipole 203 will minimally couple into orthogonal dipole 205 because opposing current vectors 305A,305B and 306A,306B cancel each other out, thereby inducing no current in dipole 205. Dual polarized antenna designs using these parasitic current cancellation techniques may improve port-to-port isolation and reduce or eliminate undesirable cross-polarization components.

Fig. 4A shows the structure of a symmetric V-shaped parasitic element 302, which includes at least two component branches or arms 401 and 403 that are joined together to form a vertex, e.g., at a right angle or substantially at a right angle. A third arm 402 may be present between the two arms to assist in the adjustment of the return loss and isolation parameters of the dual polarized antenna element 301. Additionally, the thicknesses 401A,402A, and 403A of the arms 401,402, and 403 may be adjusted to further improve performance.

In fig. 4B, parasitic elements 302A,302B,302C and 302D are distributed around dual polarized antenna element 301. Parasitic elements 302A and 302C are spaced apart from dipoles 203 and 205 by a distance of 314A. Parasitic elements 302B and 302D are spaced apart from dipoles 203 and 205 by a distance of 314B. In one example, distances 314A and 314B may be the same. However, if other antenna elements of the same array or other arrays are in close proximity, then a different relationship between distances 314A and 314B may be configured to optimize current cancellation and bandwidth improvement response.

As shown in fig. 4C, the four parasitic elements 302A,302B,302C,302D are located on a horizontal plane indicated by 404. Dipoles 203 and 205 are located in a plane indicated by 405. In one example, parasitic elements 302A,302B,302C,302D on plane 404 are aligned with plane 405. However, if other antenna elements of the same array or other arrays are in close proximity, the plane 404 of parasitic elements 302A,302B,302C,302D and the plane 405 of dipoles 203 and 205 may be different, resulting in a separation distance 406 for optimal current cancellation and bandwidth improvement. Additionally, the thickness 407 of the arms 401,402, and/or 403 on the parasitic element 302 may be adjusted to further improve coupling with the driven dipoles 203 and 205. For example, thickness 407 may be such that arms 401,402, and/or 403 partially lie within plane 405. In one example, arms 401,402, and/or 403 may be folded down, lowered down, tilted down, etc., such that arms 401,402, and/or 403 are partially within plane 405. To further improve the matching characteristics, fig. 4D shows that an additional parasitic element 408 (e.g., a patch element) may be included on top of dipoles 203 and 205.

Fig. 5 shows an antenna array 501 with dual polarized antenna elements 301, the antennaThe line array is for operation in a Low Band (LB) of RF frequencies integrated with the parasitic elements 302A,302B,302C,302D and centered in the antenna reflector 510. In fig. 5, the top of the antenna array 501 is to the left of the page. A smaller sized dual polarized antenna element designed for operation in the high frequency band (HB) of RF frequencies is located around LB dual polarized antenna element 301. The antenna elements of left HB antenna array 502A of fig. 5 may include dual-polarized "butterfly" elements 503 and 504, while the antenna elements of right HB antenna array 502B may include antenna elements 505 and 506 (also dual-polarized butterfly elements). This arrangement may be referred to as configuring 507 at i cells_iSide-by-side arrangement of HB antenna elements within. The first cell is designated as 507₁Wherein the N cells are arranged in a vertical array along the length 508 of the antenna reflector 510, the last cell being designated 507_N。

Cell configuration 507_iIs a complex RF environment where the in-band isolation of LB and HB dual polarized antenna elements may be reduced due to mutual coupling of the antenna elements. In one example, isolation may be maximized by arranging HB dual-polarized antenna elements 503,504,505 and 506 an equal distance from the corresponding LB dual-polarized antenna element 301, as defined by distance D591 along length 508 of reflector 510, and distance D592 along width 509 of reflector 510. This means that distances D591 and D592 from the center of LB dual polarized antenna element 301 to the center of each of HB dual polarized antenna elements 503,504,505 and 506 are equal.

However, in many base station antennas having a cell configuration of one LB and four HB dual polarized antenna elements as described above, the separation distances D591 and D592 are not equal. Generally, when D591 is greater than D592, the grating lobes in the elevation radiation plane occur with shallower elevation beam tilt angles. The distance of D592 may be limited to a reflector width dimension that may be used for HB dual polarized antenna elements 503,504,505 and 506 placed on the left and right sides of LB dual polarized antenna element 301. HB dual polarized antenna elements 503,504,505 and 506 may be placed as far as LB dual polarized antenna element 301 to reduce shadowing effects from larger LB component dipoles and minimize mutual interaction. Thus, unequal separation distances D591And D592 may result in an unbalanced RF environment, resulting in fewer port-to-port isolation and/or cross-polarization isolation in LB dual polarized antenna element 301. To restore a symmetric RF environment, cell 507 may be cell_NParasitic elements 302A,302B,302C,302D shown on LB dual polarized antenna element 301 are independently adjusted to optimal positions. For example, parasitic elements 302B and 302D may be separated at distance 314B, which is not equal to the separation of parasitic elements 302A and 302C at distance 314A. The unbalanced separation distance of parasitic elements 302A and/or 302C,302B and/or 302D around LB dual polarized antenna element 301 may cancel the imbalance of HB dual polarized antenna element separation distances D591 and D592. This results in improved antenna performance. It should also be noted that separation distances 314A and 314C may also be different in various examples, and the same for D591 and D592.

It should be noted that examples of the present disclosure describe the use of +45/-45 degree tilted linear polarization. However, although linear polarization is typical and examples are given using linear polarization, other embodiments of the present disclosure may be readily achieved, for example, including biorthogonal elliptical polarization or left and right hand circular polarization, as will be understood by those skilled in the art.

While the foregoing describes various examples in accordance with one or more aspects of the present disclosure, other and further examples in accordance with one or more aspects of the present disclosure may be devised without departing from the scope thereof, which is determined by the claims that follow and their equivalents.