CN108666743B - Orthogonally polarized planar array antenna designed by cross-polarization suppression method - Google Patents

Abstract

The invention discloses an orthogonal polarization plane array antenna designed by adopting a cross polarization suppression method. The antenna is mainly composed of basic arrays arranged and connected. The basic array is composed of radiating elements in a 4×4 array and connected. Each radiating element has two orthogonal feed ports, between each basic array and in the basic array. The radiating elements are connected through a feeding network, and the radiating elements and their orthogonal feed ports in each basic array are arranged in a horizontal or vertical mirror-symmetrical manner or in a horizontal and vertical mirror-symmetrical manner at the same time. Arrange. The method adopted in the present invention is suitable for various center-symmetric arrays such as circular arrays, square arrays and rectangular arrays working in linear polarization and circular polarization modes, and can be widely used in planar array antennas working in orthogonal polarization, Especially on electrically large aperture arrays.

Description

Orthogonally polarized planar array antenna designed by cross-polarization suppression method

technical field

The invention relates to a plane array antenna, in particular to an orthogonal polarization plane array antenna designed with a cross-polarization suppression method, and the feasibility is verified at the same time.

Background technique

Since the orthogonally polarized planar array antenna allows the transmission of different information within the same bandwidth, it currently plays an important role in bandwidth-sensitive satellite communications. By using the orthogonally polarized planar array antenna, the effective bandwidth of the antenna can be doubled. However, in this type of antenna, both circularly polarized and linearly polarized antennas have high requirements for cross-polarization. With the rapid development of communication-in-motion antenna technology, it is very important to suppress cross-polarization in order to avoid potential interference in satellite communications. At the same time, in order to install a streamlined radome on the satellite antenna, it is necessary to design a flat low-profile antenna to meet the requirements, which urgently requires a new technology for cross-polarization suppression.

At present, many papers have proposed a variety of methods for suppressing the cross-polarization of multi-polarized antennas. One method is to reduce the cross-polarization of the array elements by adjusting and changing the structure of the radiating element, thereby reducing the cross-polarization of the array structure. The alternating-mode coupler can effectively reduce the cross-polarization; another method is to make the adjacent elements in the antenna array mirror-symmetrical and apply the corresponding feed phase. The cross-polarization components generated by the ports of adjacent units suppress or cancel each other, although the cross-polarization performance will be greatly improved, but when designing a large array, since each array element is symmetrical with the adjacent unit, each symmetrical feeding Both may require phase inversion, so the design of the feed network is more complex than the proposed method. For example, the inversion of the microstrip line feed indicates that the electrical length of the microstrip line increases, resulting in longer microstrip line space routing and even need to take a broken line, because the limited space and other factors may make the array design more difficult.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the background art, the present invention discloses a cross-polarization suppression method for an orthogonally polarized planar array antenna.

The technical scheme adopted in the present invention is:

The antenna is designed by a proposed cross-polarization suppression method, and is an antenna structure with mirror symmetry in the horizontal or vertical directions, or mirror symmetry in the horizontal and vertical directions at the same time.

The antenna is mainly formed by arranging and connecting basic arrays. The basic array is formed by radiating elements in a 4×4 array and connecting them. Each radiating element has two orthogonal feeding ports. Each radiating element in the array is connected through a feeding network, and each radiating element in each basic array and its orthogonal feed ports are arranged in a horizontal or vertical mirror symmetrical manner or in a horizontal and vertical mirror simultaneously. Symmetrical arrangement.

The antennas are mainly composed of a top layer, a bottom layer and a ground layer between the top layer and the bottom layer. The surface of the top layer is a radiation surface, the surface of the bottom layer is a back surface, and the radiation surface and the back surface are distributed with feeding networks.

When arranged in the horizontal mirror symmetry, the radiating surface adopts the same-amplitude in-phase feed network, and the back adopts the same-amplitude anti-phase feed network; when arranged in the vertical mirror symmetry, the radiating surface adopts the same amplitude For the anti-phase feeding network, the back side adopts the same-amplitude in-phase feeding network; when the horizontal and vertical are arranged in the mirror-symmetrical manner at the same time, the radiating surface and the back side both use the same-amplitude anti-phase feeding network.

The specific arrangement structure of the equal-amplitude in-phase feeding network is a multi-stage microstrip power division network such as a Wilkinson power divider, and the number of stages of the power division network is half of the total number of antenna radiation units.

The difference between the specific arrangement structure of the equal-amplitude inverse-phase feed network and the equal-amplitude in-phase feed network is that the difference between the electrical lengths of the microstrip lines at the two output ends of the first-stage power divider is 180°.

The feeding networks on the radiating surface and the back are respectively corresponding to the two orthogonal polarizations of the antenna.

The stratum material is pure copper, and both the top layer and the bottom layer are substrates made of FR4.

The present invention is an orthogonal polarization plane array antenna designed by adopting the cross polarization suppression method.

In the present invention, the feeding network can be integrated and designed on the orthogonally polarized planar array antenna, or the antenna radiating elements can be fed separately by an independent feeding device. For a mirror-symmetrical basic array, its affiliated feeder network is mirror-symmetrical; for a mutually mirror-symmetrical basic array, the input port of its affiliated feeder network needs to be fed with a feeder network with equal-amplitude inverse output.

The invention regards the whole antenna aperture surface as being composed of even or odd basic arrays that are identical and fed through the in-phase feeding network, so that adjacent basic arrays are mirror-symmetrical to each other.

Mirror symmetry processing is performed on the basic antenna array to form an antenna structure with mirror symmetry in the horizontal or vertical directions, or mirror symmetry in the horizontal and vertical directions at the same time, so that the antenna can work in an orthogonal polarization mode.

In the present invention, the basic array is firstly symmetric or twice symmetric to obtain the orthogonal polarization plane array antenna after the cross polarization is suppressed by the mirror symmetry method. Secondly, the corresponding equal-amplitude in-phase and equal-amplitude anti-phase feed networks are designed for the basic array, so as to satisfy the equal-amplitude anti-phase feeding between the corresponding feed ports of each position of the basic array of mirror symmetry. And the specific cross-polarization isolation degree is obtained by the difference between the cross-polarization level and the main polarization level of the specific simulation or measurement.

The present invention can solve the problems existing in the existing cross-polarization suppression methods, and has the following beneficial effects:

1. There is no need to design a more complex radiating unit structure to meet the cross-polarization index, and the cross-polarization tolerance of the unit is greatly improved.

2. Compared with the symmetrical method of adjacent radiating elements, the near-field coupling effect in the tightly coupled array antenna is slightly less affected.

3. The adjustment of the basic array level makes the feeder network only need to consider the anti-phase structure design in the first power distribution. Compared with the symmetrical method of adjacent radiating units, on the premise of ensuring the cross-polarization isolation index The complexity of the antenna array is greatly reduced.

4. The applicable antenna polarization forms are wider, and the shape of the basic array is not limited to square or rectangle.

Description of drawings

FIG. 1 is a schematic diagram of the implementation process of the cross-polarization suppression method of the orthogonally polarized planar array antenna. In the figure: (a), (b), (c) represent three orthogonally polarized planar array antennas, respectively, the outer box in each sub-figure represents the basic array, 1, 2, 3, 4, 5, 6, 7 and 8 both represent the radiating element of the planar array antenna, the solid triangle in the figure represents the 0° in-phase feed port, and the solid square represents the 180° π-phase feed port.

FIG. 2 is a diagram showing the theoretical calculation result of the horizontal polarization cross-polarization isolation of the three antennas (a), (b) and (c) corresponding to FIG. 1 .

FIG. 3 is an evolution diagram of all possible structures of an orthogonally polarized planar array antenna designed with a cross-polarization suppression method.

FIG. 4 is a basic array of antennas in Embodiments 1 and 2. (a), (b), and (c) are the orthogonal dipole antenna in Embodiment 1, the 4×4 basic array radiating surface structure and the back surface structure in Embodiment 2, respectively. In the figure: 9. Dipole antenna simulating vertical polarization, 10. Dipole antenna simulating horizontal polarization, 11. Feeding port, 12. Radiating element.

FIG. 5 is a schematic diagram of connection of a plurality of basic arrays in Embodiment 2. FIG. In the figure: 13. The connection method in which the radiating elements are connected by the equal-amplitude in-phase feeding network; The left side of the figure is the connection method of the antenna radiating surface feeding network, and the right side is the connection method of the antenna backside feeding network.

FIG. 6 shows two groups of 8×4 and 8×8 orthogonally polarized planar array antennas applied in Embodiment 2. FIG.

Figure 6(a) is an array diagram of an 8×4 microstrip in-phase arrangement, the upper part represents the structure of the antenna radiation surface, and the lower part represents the structure of the back surface of the antenna.

Figure 6(b) is a diagram of an 8×4 microstrip π-phase arrangement array, the upper part represents the structure of the antenna radiation surface, and the lower part represents the structure of the back surface of the antenna.

Figure 6(c) is an array diagram of an 8×8 microstrip in-phase arrangement. The upper part represents the structure of the radiation surface of the antenna, and the lower part represents the structure of the back surface of the antenna.

Fig. 6(d) is a diagram of an 8×8 microstrip π-phase arrangement array, the upper part shows the structure of the antenna radiation surface, and the lower part shows the structure of the back surface of the antenna.

FIG. 7 is a schematic diagram of comparison between the mirror-symmetrical cross-polarization suppression method of adjacent radiation units and the suppression method proposed in the present invention. In the figure: 15. The feeding port of the plane array antenna with the symmetry of the adjacent radiating elements, 16. The feeding port of the plane array antenna with the basic array symmetry.

FIG. 8 shows a specific application structure diagram of the cross-polarization suppression method in the present invention.

The sub-figure in the upper left corner of the figure represents the circularly polarized planar array antenna, the sub-figure in the upper right corner represents the irregular cross-structured orthogonally polarized planar array antenna, and the lower sub-figure represents the basics of the irregular cross-structured orthogonally polarized planar array antenna. array.

In the figure: 17. Circularly polarized planar array antenna, 18 represents the 0° feed port (for convenience of description), 19 represents the 180° feed port, 20 represents the 90° feed port, and 21 represents the 270° feed port, respectively. 22. The orthogonally polarized planar array antenna with irregular cross structure, 23. The basic array of the orthogonally polarized planar array antenna with irregular cross structure.

FIG. 9 shows the relationship between the cross-polarization of the radiation element and the cross-polarization isolation of the orthogonally polarized planar array antenna when θ=0° calculated according to Embodiment 1.

FIG. 10 is a diagram showing the effect of improving the axial ratio of the 8×8 circularly polarized planar array antenna in FIG. 7 .

平面的水平极化交叉极化隔离度曲线图。Accompanying drawing 11 is the irregular cross structure orthogonal polarization planar array antenna in Fig. 7 in

Horizontally polarized cross-polarized isolation graph of a plane.

FIG. 12 is a diagram of the full-wave simulation result of the antenna in Embodiment 2. FIG.

FIG. 13 is a graph showing the measurement results of the anechoic chamber of the antenna in Example 2. FIG.

FIG. 14 is an analysis diagram of errors caused by the asymmetry of the antenna in Embodiment 2. FIG.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The specific implementation of the present invention adopts three kinds of antennas, as shown in the three subgraphs of (a), (b) and (c) in FIG. 1 , and the outer box in each subgraph is a basic array in the antenna.

The first type of antenna: It is mainly composed of basic arrays arranged and connected. Each basic array is shown in Figure 1(a). The basic array is composed of 16 radiating elements connected in the form of 4×4. The unit has two orthogonal feeding ports, and each basic array and each radiating element in the basic array are connected through a feeding network, and the radiating elements and their orthogonal feeding ports in each basic array are arranged in phase. , that is, the arrangement of the two orthogonal feed ports of the radiating elements in the basic array is the same as the positional arrangement of the radiating elements, and the translation and replication of each radiating element form an array arrangement.

The second type of antenna is mainly composed of basic arrays arranged and connected. Each basic array is shown in Figure 1(b). The basic array is composed of 16 radiating elements connected in the form of 4×4. The unit has two orthogonal feeding ports, and each basic array and each radiating element in the basic array are connected through a feeding network, and each radiating element in each basic array and its orthogonal feeding port are connected with each other. It is arranged in a horizontal mirror symmetrical manner, that is, the arrangement of all orthogonal feed ports of the 16 radiating elements in the basic array is the same as that of the radiating elements, and they are arranged in a horizontal mirror symmetrical manner. The straight center line is used as the axis of symmetry for horizontal mirror symmetry to form an array arrangement.

The third antenna: It is mainly composed of basic arrays arranged and connected. Each basic array is shown in Figure 1(c). The basic array is composed of 16 radiating elements connected in the form of 4×4. The unit has two orthogonal feeding ports, and each basic array and each radiating element in the basic array are connected through a feeding network, and each radiating element in each basic array and its orthogonal feeding port are connected with each other. Both horizontally and vertically are arranged in a mirror-symmetrical manner, that is, the arrangement of all orthogonal feed ports of the 16 radiating elements in the basic array is the same as the positional arrangement of the radiating elements, and they are arranged in a horizontal and vertical mirror-symmetrical manner. Each radiating unit of the array performs horizontal mirror symmetry with the vertical center line as the symmetry axis, and then performs vertical mirror symmetry with the horizontal center line as the symmetry axis to form an array arrangement.

FIG. 3 details the possible arrangements of orthogonally polarized planar array antennas with various feed structures using the cross-polarization suppression method proposed by the present invention. For example, for the upper left subgraph of Figure 3, the antenna structure can suppress the cross-polarization field of the antenna by arranging the two basic arrays in the right half and the lower half of the two basic arrays in mirror symmetry, or by arranging the left half and the lower half In the lower part, the two basic arrays are arranged in a mirror-symmetrical manner.

Embodiments of the present invention are as follows:

All antenna operating frequencies mentioned in the embodiments of the present invention are 5.8 GHz.

In order to quantitatively illustrate the suppression of cross-polarization in the far-field range, the following three formulas are used to express the cross-polarization isolation of the horizontal ports of the three antennas in Example 1:

，

，i、j分别表示天线单元的序数，i、j均为1至M和1至N的正整数集，XPD₁、XPD₂和XPD₃分别表示三种天线的交叉极化隔离度，

和

分别为辐射单元的交叉极化场和主极化场，M表示水平方向天线单元的数目，N表示竖直方向天线单元的数目，k为波矢，d为辐射单元间距，θ为以天线中心为原点时的俯仰角，

为以天线中心为原点时的方位角。in,

,

, i and j represent the ordinal numbers of the antenna elements respectively, i and j are positive integer sets from 1 to M and 1 to N, XPD ₁ , XPD ₂ and XPD ₃ respectively represent the cross-polarization isolation of the three antennas,

and

are the cross-polarization field and the main polarization field of the radiating element, M represents the number of antenna elements in the horizontal direction, N represents the number of antenna elements in the vertical direction, k is the wave vector, d is the distance between the radiating elements, and θ is the center of the antenna. is the pitch angle at the origin,

is the azimuth angle with the center of the antenna as the origin.

Example 1:

In this embodiment, as shown in FIG. 4 , the radiation unit is composed of a set of orthogonal dipole antennas, wherein one dipole antenna 10 simulates horizontal polarization, and the other dipole antenna 9 simulates vertical polarization, forming an orthogonal Dipole antenna radiating element, as shown in Figure 4(a).

比水平极化的主极化场

仅低3dB，在这种情况下计算得到XPD₁、XPD₂和XPD₃。由公式可以看出，在第二种天线的理想情况下，θ＝0°时，第二种和第三种天线的交叉极化场均会抵消。Cross-polarized field assuming vertical polarization in the horizontal direction

than the horizontally polarized main polarization field

Only 3dB lower, in this case XPD ₁ , XPD ₂ and XPD ₃ are calculated. It can be seen from the formula that in the ideal case of the second antenna, when θ=0°, the cross-polarization fields of the second and third antennas will cancel each other out.

时水平极化的交叉极化隔离度会大幅度改善。经过第二步镜像对称得到的第三种天线，

90°时水平极化的交叉极化隔离度均会大幅度改善。计算垂直极化的交叉极化隔离度时会得到类似的结果。

和

的平面即是天线的E面和H面。The second antenna obtained by mirror symmetry in the first step,

The cross-polarization isolation of the horizontal polarization will be greatly improved. The third antenna obtained by mirror symmetry in the second step,

The cross-polarization isolation of the horizontal polarization at 90° is greatly improved. Similar results are obtained when calculating cross-polarization isolation for vertical polarization.

and

The planes are the E and H planes of the antenna.

为0°的平面交叉极化隔离度会大幅度改善。When the second antenna is obtained by rearranging the basic array in the lower half of the first antenna in the vertical direction,

In-plane cross-polarization isolation at 0° is greatly improved.

From the principle analysis, it can be concluded that the mirror symmetry of the basic array makes the cross-polarization index of the orthogonally polarized planar array antenna such as the pass-in-motion antenna greatly improved at the maximum radiation direction θ=0°.

Fig. 1 shows the antennas arranged in three ways, Fig. 1(a) shows the in-phase arrangement array, and Fig. 1(b) and Fig. 1(c) both show the π-phase arrangement array. _EC and _EP represent the cross-polarized field and the main-polarized field, respectively.

Figures 1(a) to 1(b) are the first step. The first step is to rearrange the feed ports of radiating elements 1 and 2 so that they are mirror-symmetrical with the feeding ports of radiating elements 3 and 4, as shown in Fig. 1(b).

Figures 1(b) to 1(c) are the first step. The second step is to rearrange the feed ports of the radiating elements 6 and 8 so that they are mirror-symmetrical with the feeding ports of the radiating elements 5 and 7, as shown in Fig. 1(c).

平面得到改善，图2清晰的说明了阵列交叉极化隔离度变化情况，第一步使得

270°平面隔离度改善(b)，第二步使得

90°，180°，270°时隔离度均改善(c)。Through mirror symmetry at each step, the cross-polarization is gradually

The plane is improved. Figure 2 clearly illustrates the variation of the cross-polarization isolation of the array. The first step makes

270° in-plane isolation improvement (b), the second step makes

The isolation is improved at 90°, 180°, and 270° (c).

Example 2:

Example 2 uses two sets of 8×4 and 8×8 dual linearly polarized microstrip array antennas to demonstrate the above method. Each group of antennas consists of a microstrip in-phase array and a microstrip π-phase array.

As shown in FIG. 4 , the radiating surface structure of the basic array is shown in FIG. 4( b ). The radiating surface is connected by each radiating element 12 through electrode laying arrangement, and is connected to the output feeding port 11 of the basic array. The backside structure is shown in Figure 4(c).

The radiating surface and its back are evenly distributed with feeding networks, as shown in Figure 5. Taking the 8×4 microstrip orthogonally polarized planar array antenna as an example, Figures 5(a) and 5(b) are the equal-amplitude feeds respectively. network 13 and equal-amplitude inverse feed network 14. Two coaxial lines can be seen in the equal-amplitude inverting feed network 14 connected to the Wilkinson microstrip inverting power divider. The radiating element and feeding network are printed on a three-layer FR4 substrate (dielectric constant 4.3, tangent loss 0.025), the top layer is 1.6mm thick, the bottom layer is 0.5mm thick, and the middle layer is the ground layer. The dimensions are 11.4×11.6 mm ² .

As shown in Figure 6, in order to form dual polarization, feed networks are laid on both sides of the orthogonally polarized planar array. The equal-amplitude in-phase feeding network adopts single-port feeding, and the equal-amplitude anti-phase feeding network adopts dual-port feeding. The radiating surface feed excites a vertically polarized field on the antenna, and the back feed excites a horizontally polarized field on the antenna. The 8×4 microstrip in-phase arrangement of the orthogonally polarized planar array antenna is shown in Figure 6(a). The 32 radiating elements are respectively connected to the two groups of power division networks on the radiating surface and the back; The radiating surface and rear structure of the orthogonally polarized planar array antenna with π-phase arrangement are shown in Figure 6(b). Therefore, the two groups of power division networks on the back are arranged and connected to the radiating elements respectively; the 8×8 microstrip orthogonally polarized planar array antenna is arranged in phase and the radiating surface and the structure of the back are shown in Figure 6(c). The 64 radiating elements are respectively connected to the radiating surface and The two groups of power division networks on the back are arranged and connected; the 8×8 microstrip π-phase arrangement is shown in Figure 6(d), and the structure of the radiating surface and the back surface of the orthogonally polarized planar array antenna is shown in Figure 6(d). For connection, since the basic array of the antenna in the direction of the horizontal and vertical polarized electric fields is mirror-symmetrical, the four groups of power division networks on the radiating surface and the back all need to be arranged and connected to the radiating units respectively.

The difference between 8×4 and 8×8 microstrip π-phase arrays is that the former contains two 4×4 basic arrays with mirror symmetry in the horizontal direction, while the latter’s four 4×4 basic arrays are mirrored in both the horizontal and vertical directions symmetry.

The difference between the microstrip in-phase array and the π-phase array in this embodiment is that since the basic array needs to be fed with inversion every time the mirror symmetry, the designed microstrip inversion power divider is designed to provide the two mirror-symmetrical ports of the antenna. Differential phase, so that the microstrip π-phase array needs more than two (not including two) feeding ports to feed the horizontal polarization and vertical polarization of the basic array that are mirror-symmetrical to each other.

和

的平面天线阵列的交叉极化隔离度，其次在微波暗室中借助矢量网络分析仪测量计算得到实物的交叉极化隔离度。obtained by simulation

and

The cross-polarization isolation of the planar antenna array is measured and calculated in the microwave anechoic chamber with the help of a vector network analyzer.

Among them, the two microstrip π-phase arrays have achieved great improvement in the maximum radiation direction θ=0°, and the 8×8 array has achieved better cross-polarization in a larger radiation angle range. isolation.

平面水平极化和垂直极化的交叉极化隔离度仿真结果，图13表示两种阵列分别在

平面水平极化和垂直极化的交叉极化隔离度测量结果。其中的微带π相排布阵列分别对应图1中平面阵列天线(a)经过一次和两次镜像对称得到的平面阵列天线(b)和平面阵列天线(c)，8×4微带π相排布阵列为水平方向基本阵列对称的天线。在理想情况下天线远场的交叉极化性能会在大角度范围内极大改善。由微带同相和π相排布阵列对比可见，交叉极化隔离度会有效改善，尤其在最大辐射方向θ＝0°，仿真实验得到的改善效果在60dB以上，暗室测量得到的改善效果在10dB以上。Figures 12 and 13 compare the simulated and measured cross-polarization isolation results for 8×4 and 8×8 microstrip in-phase and π-phase arrays.

The simulation results of cross-polarization isolation of plane horizontal polarization and vertical polarization, Fig. 13 shows that the two arrays are

Cross-polarization isolation measurement results for planar horizontal and vertical polarizations. The microstrip π-phase arrays correspond to the planar array antenna (a) obtained by one and two mirror symmetry in Fig. 1, respectively, the planar array antenna (b) and the planar array antenna (c), 8×4 microstrip π-phase arrays. The arrangement array is an antenna whose basic array is symmetrical in the horizontal direction. In an ideal case, the cross-polarization performance of the far field of the antenna will be greatly improved over a large angle range. It can be seen from the comparison of the microstrip in-phase and π-phase arrays that the cross-polarization isolation can be effectively improved, especially in the maximum radiation direction θ=0°, the improvement effect obtained by the simulation experiment is more than 60dB, and the improvement effect obtained by the darkroom measurement is 10dB. above.

The asymmetry of the basic array will affect the cross-polarization isolation of the orthogonally polarized planar array antenna to a certain extent. According to the relationship between the isolation degrees, an orthogonally polarized planar array antenna designed with a cross-polarization suppression method is more sensitive to asymmetry.

Based on the formulas for calculating the cross-polarization isolation of the three antennas in Example 1, the curve results shown in Figure 9 can be calculated and obtained. The horizontal axis represents the horizontal polarization or vertical polarization cross-polarization isolation of the radiation element, and the vertical axis represents the plane Array antenna cross-polarization isolation. Ideally, the element cross-polarization has no effect on the mirror-symmetric planar array antenna, and the planar array antenna cross-polarization is completely suppressed at θ=0°. It can be seen that the present invention does not need to design a relatively complex radiating element structure to meet the cross-polarization index, and the tolerance to the cross-polarization of the element is greatly improved.

Fig. 7 shows a close-coupled planar array antenna with symmetrical adjacent radiating elements and a closely-coupled planar array antenna with symmetrical basic arrays, and the spacing between the radiating elements is one third of a wavelength. In the method of symmetry between adjacent radiating elements, for antennas with the same size and shape, the energy coupling between the two adjacent element ports 15 in the center is about -18.3dB. However, this suppression method has been verified by simulation. For a tightly coupled planar array antenna, the energy coupling of the two adjacent unit ports 16 in the center is about -21.3dB, and the near-field coupling is slightly smaller. It can be seen that, compared with the method in which the adjacent radiating elements are symmetrical, the influence of the near-field coupling effect in the tightly coupled array antenna is slightly smaller.

As shown in Figure 7, due to the symmetry of adjacent radiating elements, it is also necessary to ensure that the feeding phase is reversed. Therefore, in the case of using a feeding microstrip line for feeding, the symmetric radiating element feeding microstrip line needs to change due to its electrical length. , so its physical size needs to be redesigned. In this case, it is often necessary to extend the feeding microstrip line, and it is difficult to design the feeding network when the surface space of the antenna is limited. Assuming that the complexity of one inversion is 1, the method proposed in the present invention only needs to invert the phase once for horizontal polarization or vertical polarization, and the complexity is 2. The complexity of the method for symmetry of adjacent radiation units is n, where n is the total number of radiation units. It can be seen that the adjustment of the basic array level of the present invention makes the feeder network only need to consider the anti-phase structure design during the first power distribution. Compared with the symmetrical method of adjacent radiating elements, the cross-polarization isolation is guaranteed. Under the premise of the index, the complexity of the antenna array is greatly reduced.

FIG. 8 shows the circularly polarized planar array antenna 17 and the irregular cross-structured orthogonally polarized planar array antenna 22 after mirror symmetry. The 0° feed port 18 and 90° feed port 20 of the circularly polarized planar array antenna are mirror-symmetrical, and the 180° feed port 19 and 270° feed port 21 are mirror-symmetrical. The irregular cross-structured orthogonally polarized planar array antenna consists of A basic array 23 comprising three radiating elements is formed. It can be seen from Fig. 10 that the axial ratio (AR) of the circularly polarized planar array antenna in the maximum radiation direction can be improved by using the cross-polarization suppression method. Figure 11 shows that the cross-polarization suppression method can also greatly improve the cross-polarization isolation of the irregular cross-structured orthogonally polarized planar array antenna. It can be seen that the antenna polarization forms applicable to the present invention are wider, and the shape of the basic array is not limited to square or rectangle.

It can be seen that the present invention adopts the method of arranging the mirror-symmetrical basic arrays of the radiation aperture surface, and regards the surface of the planar array antenna as composed of even or odd basic arrays with the same number of radiating elements, and makes the adjacent basic arrays mirror-symmetrical. A good cross-polarization suppression effect is obtained. For the basic arrays that are mirror-symmetrical to each other, the equal-amplitude anti-phase method is used to feed, and the symmetrical characteristics of the antenna are used to ensure that the cross-polarized field radiated by each basic array is in the far field under the condition that the main polarized field is basically unaffected. In the beam range, especially in the normal radiation direction, mutual suppression.

Claims (5)

1. An orthogonal polarization plane array antenna designed by adopting a cross polarization suppression method is characterized in that: the antenna structure is mirror-symmetrical in the horizontal or vertical direction or mirror-symmetrical in the horizontal and vertical directions simultaneously;

the antenna structure mainly comprises a top layer, a bottom layer and a ground layer positioned between the top layer and the bottom layer, wherein the surface of the top layer is a radiation surface, the surface of the bottom layer is a back surface, and feed networks are uniformly distributed on the radiation surface and the back surface;

the antenna comprises more than two basic arrays which are arranged and connected, wherein each basic array comprises a plurality of radiating elements with two orthogonal feed ports, the radiating elements between the basic arrays and among the basic arrays are connected through a feed network, the radiating elements and the orthogonal feed ports thereof between the adjacent basic arrays are arranged in a horizontal or vertical mirror symmetry mode or in a horizontal and vertical simultaneous mirror symmetry mode, and the antenna specifically comprises the following components:

when the antenna structures are arranged in the horizontal mirror symmetry mode, the radiation surface adopts a constant-amplitude in-phase feed network, the back surface adopts a constant-amplitude reverse-phase feed network, the adjacent basic arrays are in mirror symmetry along the horizontal direction, the horizontal ports and the vertical ports are in mirror symmetry along the horizontal direction, the radiation units of different basic arrays feed reverse phases through the horizontal ports, and the vertical ports feed in phase;

when the antenna structures are arranged in the vertical mirror symmetry mode, the radiation surface adopts a constant-amplitude reverse-phase feed network, the back surface adopts a constant-amplitude in-phase feed network, the adjacent basic arrays are in mirror symmetry along the vertical direction, the horizontal ports and the vertical ports are in mirror symmetry along the vertical direction, the vertical ports of the radiation units of different basic arrays are in phase opposition, and the horizontal ports are in phase;

when the antenna structures are arranged in the horizontal and vertical simultaneous mirror symmetry mode, equal-amplitude reverse feed networks are adopted on the radiation surfaces and the back surfaces, adjacent basic arrays are in simultaneous mirror symmetry along the horizontal and vertical directions, horizontal ports are in mirror symmetry along the horizontal direction, vertical ports are in mirror symmetry along the vertical direction, radiation units of different basic arrays are in reverse phase at the horizontal ports and in reverse phase at the vertical ports.

2. An orthogonal polarization planar array antenna designed by the cross polarization suppression method according to claim 1, wherein: the specific arrangement structure of the constant-amplitude in-phase feed network is a multistage micro-strip power dividing network of a Wilkinson power divider, and the stage number of the power dividing network is one half of the total number of the radiation units.

3. An orthogonal polarization planar array antenna designed by the cross polarization suppression method according to claim 1, wherein: the specific arrangement structure of the constant-amplitude reverse phase feed network is different from that of the constant-amplitude in-phase feed network in that the difference of the line lengths of the micro-strip lines at the two output ends of the first-stage power divider is 180 degrees.

4. An orthogonal polarization planar array antenna designed by the cross polarization suppression method according to claim 2, wherein: the ground layer material is pure copper, and the top layer and the bottom layer are both base plates made of FR 4.

5. A cross polarization suppression method of an orthogonal polarization plane array antenna is characterized in that: carrying out mirror symmetry processing on the antenna basic array to form an antenna structure which is mirror symmetric in the horizontal or vertical direction or mirror symmetric in the horizontal and vertical directions simultaneously, so that the antenna can work in an orthogonal polarization mode; the method specifically comprises the following steps:

the antenna comprises more than two basic arrays which are arranged and connected, wherein each basic array comprises a plurality of radiating elements with two orthogonal feed ports, the radiating elements between the basic arrays and among the basic arrays are connected through a feed network, the radiating elements and the orthogonal feed ports thereof between the adjacent basic arrays are arranged in a horizontal or vertical mirror symmetry mode or in a horizontal and vertical simultaneous mirror symmetry mode, and the antenna specifically comprises the following components:

when the antenna structures are arranged in the horizontal mirror symmetry mode, the radiation surface adopts a constant-amplitude in-phase feed network, the back surface adopts a constant-amplitude reverse-phase feed network, the adjacent basic arrays are in mirror symmetry along the horizontal direction, the horizontal port and the vertical port are in mirror symmetry along the horizontal direction, the radiation units of different basic arrays are in feed reverse phase through the horizontal port, and the vertical ports are in feed in phase;

when the antenna structures are arranged in the vertical mirror symmetry mode, the radiation surface adopts a constant-amplitude reverse-phase feed network, the back surface adopts a constant-amplitude in-phase feed network, the adjacent basic arrays are in mirror symmetry along the vertical direction, the horizontal ports and the vertical ports are in mirror symmetry along the vertical direction, the vertical ports of the radiation units of different basic arrays are in phase opposition, and the horizontal ports are in phase;

when the antenna structures are arranged in the horizontal and vertical simultaneous mirror symmetry mode, equal-amplitude reverse feed networks are adopted on the radiation surfaces and the back surfaces, adjacent basic arrays are in simultaneous mirror symmetry along the horizontal and vertical directions, horizontal ports are in mirror symmetry along the horizontal direction, vertical ports are in mirror symmetry along the vertical direction, radiation units of different basic arrays are in reverse phase at the horizontal ports and in reverse phase at the vertical ports.

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