阅读说明：本技术 一种基于多模谐振的宽频带低剖面圆极化微带天线 (Broadband low-profile circularly polarized microstrip antenna based on multimode resonance ) 是由 胡伟 李长江 胡志鹏 林聪� 陈霑 姜文 于 2020-11-23 设计创作，主要内容包括：本发明公开了一种基于多模谐振的宽频带低剖面圆极化微带天线。该天线具有两层结构,第一层为印刷在上介质板上层具有旋转对称特性的辐射结构,包括四个驱动贴片、四个寄生贴片和四个金属墙,寄生贴片通过空隙与驱动贴片耦合,金属墙放置在介质板的边缘并向下弯折；驱动贴片与寄生贴片分别通过金属柱与馈电网络和地板相连。第二层为印刷在下介质板上层的地板以及下层的馈电网络,包括二阶的威尔金森功分器和90°宽带移相器；两层结构之间由空气层隔开。此天线具有频带宽、剖面低、结构简单、带内增益平缓等优点,适合用于电子对抗、导弹制导、卫星通讯等领域中。(The invention discloses a broadband low-profile circularly polarized microstrip antenna based on multimode resonance. The antenna has a two-layer structure, wherein the first layer is a radiation structure printed on the upper layer of an upper dielectric plate and has a rotational symmetry characteristic, and comprises four driving patches, four parasitic patches and four metal walls, the parasitic patches are coupled with the driving patches through gaps, and the metal walls are arranged on the edge of the dielectric plate and bent downwards; the driving patch and the parasitic patch are respectively connected with the feed network and the floor through metal columns. The second layer is printed on the floor on the upper layer of the lower dielectric plate and the feed network on the lower layer, and comprises a second-order Wilkinson power divider and a 90-degree broadband phase shifter; the two layers are separated by an air layer. The antenna has the advantages of wide frequency band, low section, simple structure, mild in-band gain and the like, and is suitable for the fields of electronic countermeasure, missile guidance, satellite communication and the like.)

1. A broadband low-profile circularly polarized microstrip antenna based on multimode resonance is characterized in that the antenna comprises two layers of dielectric plates, wherein a first layer of dielectric plate (1) comprises four driving patches (3), four parasitic patches (4) and four metal walls (5) printed on the first layer of dielectric plate; the second layer of dielectric plate (2) comprises a floor (15) printed on the upper layer and a feed network (6) printed on the lower layer; a metal column (7) and a feed probe (8) which are connected with the interlayer dielectric plate are arranged between the two dielectric plates; the two dielectric plates are separated by an air layer;

a metal disc (16) is arranged on the driving patch (3), and the metal disc (16) is connected to the feed network (6) through a feed probe (8) to carry out coupling feed; the metal wall (5) is bent downwards along the edge of the first layer of dielectric plate (1) to be connected with the grounding plate (15), so that radiation of the broadband low-profile circularly polarized antenna is realized, and in-band gain is improved.

2. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein the four driving patches (3) and the four parasitic patches (4) are distributed on the upper layer of the first dielectric slab (1) at intervals, and the metal walls (5) are symmetrically distributed on the first dielectric slab (1) in pairs to form a radiation structure on the upper layer of the first dielectric slab.

3. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein said driving patches (3) are narrow rectangular metal patches, four driving patches (3) are symmetrically distributed on the upper layer of the first dielectric plate (1), a gap is left in the middle, and the edges of the driving patches are connected with the metal posts (7).

4. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein said parasitic patches (4) are wide rectangular metal patches, four parasitic patches (4) are symmetrically distributed between the driving patches (3) at intervals, and a gap is left between the four driving patches (3); the edge of the metal column is connected with the metal column (7).

5. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein the metal walls (5) are bent rectangular metal patches, four metal walls (5) are symmetrically distributed on the edge of the first dielectric plate (1) in a pairwise staggered manner, a gap is left between the upper part of the metal walls (5) and the parasitic patch (4), and the edge is bent downwards and connected with the floor (15).

6. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein the two dielectric plates are rectangles with the same area; the feed probe (8) penetrates through the two layers of dielectric plates to be connected with the feed network (6); the metal column (7) penetrates through the first layer of dielectric plate (1) to be connected with the floor (15).

7. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein said feeding network (6) comprises three second-order Wilkinson power dividers (13) and four 90 ° broadband phase shifters (14) printed on the second dielectric plate (2); the tail ends of the feeder lines of the second-order Wilkinson power divider (13) and the 90-degree broadband phase shifter (14) are two-in-one ports; the end ports of the middle second-order Wilkinson power divider (13) are respectively connected with a 90-degree broadband phase shifter (14) and a right second-order Wilkinson power divider (13); one-to-two ports of the left and right two-side second-order Wilkinson power dividers (13) are respectively connected with a 90-degree broadband phase shifter (14) and a feeder line.

8. The broadband low-profile circularly polarized microstrip antenna based on the multimode resonance as claimed in claim 7, wherein two resistors are respectively arranged between two feeder lines with different distances on the second-order Wilkinson power divider (13); the tail end of the 90-degree broadband phase shifter (14) is connected with a floor (15) through a phase shifter metal column (7).

9. The broadband low-profile circularly polarized microstrip antenna based on the multimode resonance is characterized in that the first dielectric plate (1) and the second dielectric plate (2) are respectively FR4 dielectric plates and Rogers RO4003 dielectric plates with the thicknesses of 0.5mm and 0.8 mm; the thickness of the air layer between the first layer of dielectric plate (1) and the second layer of dielectric plate (2) is 5 mm.

10. The broadband low-profile circularly polarized microstrip antenna based on multimode resonance as claimed in claim 1, wherein the antenna center frequency is 3GHz, the relative impedance bandwidth is not less than 97%, and the axial ratio bandwidth reaches 86%; the XOZ plane directional diagram of the antenna is nearly consistent with the YOZ plane directional diagram; the in-band gain is gentle; the maximum gain is not less than 8 dBic.

Technical Field

The invention relates to an antenna design technology in the field of wireless communication, in particular to a broadband low-profile circularly polarized microstrip antenna based on multimode resonance.

Background

Modern communication systems require stable communication under complex environments and conditions, which places high demands on antenna stability and interference immunity. The circular polarization can be widely applied to the fields of electronic countermeasure, missile guidance, satellite communication and the like due to the advantages of avoiding polarization loss, inhibiting multipath interference and the like. With the rapid development of modern wireless communication technology, people have made higher and higher requirements on the bandwidth of communication equipment, so in recent years, broadband circularly polarized antennas have become a hot spot of research.

Disclosure of Invention

The invention aims to solve the technical problem of realizing broadband characteristics by utilizing multimode resonance, reducing the height of the antenna section through a parasitic structure and realizing a broadband low-section circularly polarized antenna. The antenna has the characteristics of wide frequency band, low section, simple structure, mild in-band gain and the like.

The invention is realized by the following technical scheme.

A broadband low-profile circularly polarized microstrip antenna based on multimode resonance comprises two layers of dielectric plates, wherein the first layer of dielectric plate comprises four driving patches, four parasitic patches and four metal walls printed on the first layer of dielectric plate; the second layer of dielectric plate comprises a floor printed on the upper layer of the second layer of dielectric plate and a feed network printed on the lower layer of the second layer of dielectric plate; a metal column and a feed probe which are connected with the interlayer dielectric plate are arranged between the two dielectric plates; the two dielectric plates are separated by an air layer;

the driving patch is provided with a metal disc, and the metal disc is connected to a feed network through a feed probe to carry out coupling feed; the metal wall is bent downwards along the edge of the first layer of dielectric plate to be connected with the grounding plate, so that the radiation of the broadband low-profile circularly polarized antenna is realized, and the in-band gain is improved.

With respect to the above technical solutions, the present invention has a further preferable solution:

preferably, the four driving patches and the four parasitic patches are distributed on the upper layer of the first dielectric slab at intervals, and the metal walls are symmetrically distributed on the first dielectric slab in pairs to form a radiation structure on the upper layer of the first dielectric slab.

Preferably, the driving patches are narrow rectangular metal patches, the four driving patches are symmetrically distributed on the upper layer of the first layer of dielectric slab, a gap is reserved in the middle of the driving patches, and the edges of the driving patches are connected with the metal columns.

Preferably, the parasitic patches are wide rectangular metal patches, four parasitic patches are symmetrically distributed among the driving patches at intervals, and gaps are reserved between the four parasitic patches and the four driving patches; the edge of the metal column is connected with the metal column.

Preferably, the metal walls are bent rectangular metal patches, the four metal walls are symmetrically distributed on the edge of the first layer of dielectric slab in a pairwise staggered manner, a gap is reserved between the upper part of each metal wall and the parasitic patch, and the edge of each metal wall is bent downwards to be connected with the floor.

Preferably, the two dielectric plates are rectangles with the same area; the feed probe penetrates through the two layers of dielectric plates and is connected with a feed network; the metal column penetrates through the first layer of dielectric plate to be connected with the floor.

Preferably, the feed network comprises three second-order wilkinson power dividers and four 90-degree broadband phase shifters printed on the second-layer dielectric plate; the two-step Wilkinson power divider and the tail end of a feeder line of the 90-degree broadband phase shifter are both one-to-two ports; the end ports of the middle second-order Wilkinson power divider are respectively connected with a 90-degree broadband phase shifter and a right second-order Wilkinson power divider; one-to-two ports of the left and right two-side second-order Wilkinson power dividers are respectively connected with a 90-degree broadband phase shifter and a feeder line.

Preferably, two resistors are respectively arranged between two feeder lines with different distances on the second-order Wilkinson power divider; the tail end of the 90-degree broadband phase shifter is connected with the floor through a phase shifter metal column.

Preferably, the first layer of dielectric plate and the second layer of dielectric plate are FR4 dielectric plates and Rogers RO4003 dielectric plates respectively, and the thicknesses of the first layer of dielectric plate and the second layer of dielectric plate are 0.5mm and 0.8mm respectively; the thickness of the air layer between the first dielectric plate and the second dielectric plate is 5 mm.

The invention has the beneficial effects that:

the invention designs and invents a broadband low-profile circularly polarized microstrip antenna based on multimode resonance by combining a parasitic patch based on a multimode resonance theory. In order to reduce the profile height of the antenna, a parasitic patch is introduced on the first dielectric plate, and the parasitic patch is coupled with the driving patch so that the resonance point of the driving patch shifts to a low frequency. In order to widen the impedance bandwidth of the antenna, a metal column structure is introduced and loaded on the driving patch and the parasitic patch respectively, and three resonance modes are generated. The antenna is subjected to impedance matching by optimizing the geometric parameters of the two patches and the positions of the metal columns, so that the broadband effect is achieved. In order to improve the in-band gain, a metal wall is printed on the upper layer of the first dielectric plate, and the metal wall can provide magnetic current components at corresponding resonance points, so that the in-band gain is improved.

Meanwhile, a sequential rotation structure is adopted, and a broadband power division phase shifter is utilized, so that a wider axial ratio bandwidth is realized. The second-order Wilkinson power divider provides equal-amplitude same-direction excitation, and meanwhile, two chip resistors with different resistance values are loaded on the second-order Wilkinson power divider respectively so as to further improve the isolation degree between the two output ports. In addition, a stable phase difference can be maintained in a wide frequency band by the wide-band phase shifter. And the floor is placed below the antenna, so that the radiation pattern of the antenna has good directivity, and the maximum radiation direction in the whole working frequency band is ensured to be positioned right above the antenna.

The antenna has the advantages of wide frequency band, low section, simple structure, mild in-band gain and the like, the center frequency of the antenna is 3GHz, the relative impedance bandwidth is not less than 97%, and the axial ratio bandwidth reaches 86%; the XOZ plane directional diagram of the antenna is nearly consistent with the YOZ plane directional diagram; the in-band gain is gentle; the maximum gain is not less than 8 dBic. The antenna is suitable for the fields of electronic countermeasure, missile guidance, satellite communication and the like.

Drawings

FIG. 1 is a schematic perspective view of a circularly polarized antenna according to the present invention;

FIG. 2 is a top view of the overall structure of the circularly polarized antenna of the present invention;

FIG. 3 is a side view of the overall structure of the circularly polarized antenna of the present invention;

FIG. 4 is a bottom view of the feed network of the circularly polarized antenna of the present invention;

FIGS. 5(a) and (b) are schematic diagrams of a second-order Wilkinson power divider and a broadband phase shifter of the circularly polarized antenna according to the present invention, respectively;

FIG. 6 is a graph of the reflection coefficient of the circularly polarized antenna of the present invention;

FIG. 7 is a graph of axial ratio of the circularly polarized antenna of the present invention;

FIG. 8 is the main polarization and cross polarization directional diagram of the XOZ plane of the circularly polarized antenna of the present invention at 2.0 GHz;

FIG. 9 is a diagram of the YOZ plane main polarization and cross polarization directional diagram of the circularly polarized antenna of the present invention at 2.0 GHz;

FIG. 10 is the main polarization and cross polarization directional diagram of the XOZ plane of the circularly polarized antenna of the present invention at 2.5 GHz;

FIG. 11 is a diagram of the YOZ plane main polarization and cross polarization directional diagram of the circularly polarized antenna of the present invention at 2.5 GHz;

FIG. 12 is the main polarization and cross polarization directional diagram of the XOZ plane at 3.5GHz for the circularly polarized antenna of the present invention;

FIG. 13 is a diagram of the YOZ plane main polarization and cross polarization directional diagram of the circularly polarized antenna of the present invention at 3.5 GHz;

fig. 14 is a graph of the main polarization gain of the circular polarization antenna of the present invention.

In the figure: 1. a first dielectric slab; 2. a second layer of dielectric sheet; 3. driving the patch; 4. a parasitic patch; 5. a metal wall; 6. a feed network; 7. a metal post; 8. a feed probe; 9. a feed port; 10. a phase shifting wire metal post; 11. a resistance of 100 Ω; 12. a 200 omega resistor; 13. a second-order Wilkinson power divider; 14. a 90 degree broadband phase shifter; 15. a floor; 16. a metal disc.

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, the present invention is further described in detail with reference to the accompanying drawings and examples, but without limitation thereto.

Fig. 1 is a schematic structural diagram of a multimode resonance-based broadband low-profile circularly polarized microstrip antenna according to the present invention. This figure shows an exploded view of the antenna structure. The antenna has a two-layer structure, wherein a first layer of dielectric plate 1 is a radiation structure printed on the upper layer of the dielectric plate and has a rotational symmetry characteristic, and mainly comprises four driving patches 3, four parasitic patches 4 and four metal walls 5; the second layer of dielectric plate 2 is a floor 15 printed on the upper layer of the dielectric plate and a feed network 6 printed on the lower layer of the dielectric plate; the feed network 6 comprises three second-order wilkinson power dividers 13 and four broadband phase shifters 14, provides balanced feed for the radiation structure, and simultaneously realizes impedance matching in a broadband. A metal column 7 and a feed probe 8 which are connected with the first layer of dielectric plate 1 and the second layer of dielectric plate 2 are arranged between the two layers of dielectric plates, and the feed probe 8 penetrates through the first layer of dielectric plate and the second layer of dielectric plate; the metal posts 7 penetrate through the first dielectric plate. Finally, the radiation of the broadband low-profile circularly polarized antenna is realized.

As shown in fig. 2, four driving patches 3, four parasitic patches 4 and four metal walls 5 are located on the upper layer of the first dielectric slab, wherein the four driving patches 3 and the four parasitic patches 4 are distributed on the upper layer of the first dielectric slab 1 at intervals, and the metal walls 5 are symmetrically distributed on the first dielectric slab 1 two by two to form a radiation structure on the upper layer of the first dielectric slab.

The driving patches 3 are narrow rectangular metal patches, the four driving patches 3 are symmetrically distributed on the upper layer of the first layer of dielectric slab 1, a gap is reserved in the middle of each driving patch, and the edges of each driving patch are connected with the metal columns. The parasitic patches 4 are wide rectangular metal patches, four parasitic patches 4 are symmetrically distributed among the driving patches 3 at intervals, and gaps are reserved between the four parasitic patches 4 and the four driving patches 3; the edge of the metal column is connected with the metal column. The metal walls 4 are bent rectangular metal patches, the four metal walls 5 are symmetrically distributed on the edge of the first layer of dielectric slab 1 in a pairwise staggered manner, a gap is reserved between the upper part of each metal wall 5 and the parasitic patch 4, and the edge of each metal wall is bent downwards to be connected with the floor 15.

The driving patch 3 is coupled and fed through the metal disc 16, the metal disc 16 is connected to the feeding network 6 through a feeding probe, the parasitic patch 4 is coupled with the driving patch 3, and the metal wall 5 is coupled with the parasitic patch 4.

As shown in fig. 3, the first dielectric plate 1 and the second dielectric plate 2 are rectangular with the same area, and are separated by an air layer with the thickness of H2; the feed port 9 provides excitation for the feed network 6; the feed probe 8 passes through the first and second dielectric plates to be connected with the feed network 6; the metal column 7 passes through the first layer of medium plate to be connected with the floor 15.

As shown in fig. 4, the feed network 6 comprises three second order wilkinson power dividers 13 and four 90 ° broadband phase shifters 14 printed on the second layer dielectric plate 2. 100 omega resistors 12 and 200 omega resistors 13 are respectively arranged between two feeder lines with different distances of the second-order Wilkinson power divider 13 so as to improve the isolation between ports, and the tail ends of the feeder lines of the second-order Wilkinson power divider 14 and the 90-degree broadband phase shifter 14 are two-in-one ports.

The end ports of the middle second-order Wilkinson power divider 13 are respectively connected with a 90-degree broadband phase shifter 14 and a right second-order Wilkinson power divider; one-to-two ports of the left and right two-side second-order Wilkinson power dividers 13 are respectively connected with a 90-degree broadband phase shifter 14 and a feeder line.

Fig. 5(a) is a schematic structural diagram of a second-order wilkinson power divider, in which a 100 Ω resistor 11 and a 200 Ω resistor 12 are respectively disposed between two feeder lines with different pitches, and the ends of the feeder lines are two-in-one ports. A one-to-four feed network now provides phase differences of 0, 90, 180, 270, respectively. Fig. 5(b) shows a 90 ° broadband phase shifter 14 structure in which the end of the 90 ° broadband phase shifter 14 is connected to the phase shifting wire metal post 10.

In one embodiment:

the first dielectric board layer is FR4 with the thickness of 140mm multiplied by 0.5mm, and the dielectric constant is 4.4;

the first dielectric slab was a Rogers RO4003 of 140mm by 0.8mm with a dielectric constant of 3.5.

In this embodiment, the center frequency of the antenna is 3GHz, the relative impedance bandwidth is not less than 97%, and the axial ratio bandwidth reaches 86%.

The structures are closely matched with each other and optimally designed to realize the circularly polarized antenna working under a wider frequency band.

Other structural dimensions are shown in table 1.

TABLE 1

Wherein W is the width of the first and second layers of rectangular dielectric slabs; l is the length of the first and second layers of rectangular dielectric slabs; l1 is the length of the drive patch; w1 is the width of the drive patch; l2 is the length of the parasitic patch; w2 is the width of the parasitic patch; l3 is the distance between a pair of metal posts on the parasitic patch; w3 is the distance between the metal post and the edge of the parasitic patch; l4 is the distance between a pair of metal posts on the drive patch; l5 is the length of the metal wall; w5 is the width of the metal wall; r1 is the radius of the metal disc; r2 is a round hole on the driving patch and is slightly larger than R1, so that the capacitive coupling effect is achieved; r3 is the radius of the metal post loaded on the drive patch; r4 is the radius of the metal posts loaded on the parasitic patch; h1 is the thickness of the first layer dielectric plate; h2 is the thickness of the air layer; h3 is the thickness of the second layer dielectric slab.

The broadband low-profile principle of the antenna is as follows: the four rotationally symmetric driving patches are fed with excitation with the same amplitude, the phase difference of 0 degrees, 90 degrees, 180 degrees and 270 degrees, and meanwhile, the parasitic patches are adopted, and two resonance points are introduced, so that the broadband effect is achieved; the introduction of the parasitic patch also moves the resonance point of the driven patch, thereby achieving a low profile effect. Wherein the driving patch operates at low frequency and the parasitic patch operates at high frequency. By optimizing the geometrical parameters of the dipole, the antenna is subjected to impedance matching, so that the curves of the high frequency band and the low frequency band are smooth and communicated, and the broadband effect is achieved.

And finally, a weak coupling feed network structure is adopted, and a broadband power division phase shifter is utilized, so that a wider axial ratio bandwidth is realized. The two-order Wilkinson power divider is matched with the two chip resistors with different resistance values, so that the isolation between the two output ports is improved. In addition, the wide band phase shifter can maintain a stable phase difference over a wide frequency band by utilizing coupling between the microstrip lines. And the floor is placed below the antenna, so that the radiation pattern of the antenna has good directivity, and the maximum radiation direction in the whole working frequency band is ensured to be positioned right above the antenna. The structures are arranged and act together to form a good broadband low-profile circularly polarized antenna.

The broadband low-profile circularly polarized antenna is designed by utilizing the parasitic patch and the metal column for loading based on multimode resonance, and the frequency bandwidth of the broadband circularly polarized antenna can be quickly, conveniently and flexibly adjusted by changing the shape and the size of the driving patch and the parasitic patch, the size of a metal wall, the size of a broadband power division phase shifter and other parameter variables.

As shown in fig. 6, a reflection coefficient graph of the present embodiment is shown. Preferably, the center frequency of the broadband circularly polarized antenna is 3GHz, and the relative impedance bandwidth is not less than 97%.

As shown in fig. 7, it is an axial ratio parameter graph of the present embodiment. Preferably, the center frequency of the broadband circularly polarized antenna is 3GHz, and the axial ratio bandwidth reaches 86%.

As shown in fig. 8, the XOZ plane main polarization and cross polarization directional diagram of this embodiment at 2.0GHz has good directivity and symmetry in the main radiation direction.

As shown in fig. 9, the pattern of the principal polarization and the cross polarization of the YOZ plane of this embodiment at 2.0GHz has good directivity and symmetry in the principal radiation direction.

As shown in fig. 10, the XOZ plane main polarization and cross polarization directional diagram of this embodiment at 2.5GHz has good directivity and symmetry in the main radiation direction.

As shown in fig. 11, the pattern of the principal polarization and the cross polarization of the YOZ plane of this embodiment at 2.5GHz has good directivity and symmetry in the principal radiation direction.

As shown in fig. 12, the XOZ plane main polarization and cross polarization directional diagram of this embodiment at 3.5GHz has good directivity and symmetry in the main radiation direction.

As shown in fig. 13, the pattern of the principal polarization and the cross polarization of the YOZ plane at 3.5GHz in this example has good directivity and symmetry in the principal radiation direction.

As shown in fig. 14, which is a graph of the main polarization gain of the present embodiment, the gain is relatively flat in the frequency band, and the maximum gain is not less than 8 dBic.

The broadband low-profile circularly polarized antenna provided by the invention is described in detail, and the principle and the implementation mode of the invention are explained and realized by applying the detailed structural design parameters. The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.