A filter patch antenna with cross-polarization suppression

Abstract

The application is suitable for the field of communication equipment technology improvement, and provides a filtering patch antenna with cross polarization suppression, which comprises a patch radiator, a filtering feed structure and a ground plate, the lower surface of the filtering feed structure is connected with a coaxial line through the ground plate, the upper surface of the filtering feed structure is connected with the lower surface of the patch radiator, and the filtering feed structure is filtered and fed according to two C-shaped microstrip line networks. The filtering function can be realized without increasing the volume of the antenna, the omnidirectional consistency of filtering is ensured, the filtering antenna also has the function of suppressing the cross polarization of the patch antenna, and the working performance of the antenna is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of technical improvement of communication equipment, and particularly relates to a filtering patch antenna with cross-polarization suppression. BACKGROUND

[0002] All hardware parts of wireless communication equipment have a radio frequency front end, and the antenna as the first or last functional module of the radio frequency front end plays an important role in the communication ability of the equipment. Meanwhile, the filter as a module closely connected with the antenna has the function of suppressing out-of-band signals or noise, and also has a great influence on the communication quality. Although they should be independent of each other in terms of function, in recent years, a method of fusion design of the filter and the antenna has been developed, that is, the filtering antenna, the design concept of which is shown in Figure One The advantages of fusion design of the two are: 1. It can avoid the extra loss caused by the transmission line or matching network. 2. It can save the volume of the system, which is conducive to miniaturization design.

[0003] The currently popular implementation method (method one) of the filtering antenna is to take the antenna as a resonator load at the end of a band-pass filter network, so that a good overall band-pass filtering effect can be obtained as long as the front band-pass filtering network is reasonably designed. The basic idea of this design method is to equivalent the antenna into an RLC network, and then obtain the specific parameters of the network through simulation fitting, and then design a band-pass filter according to the general steps on the basis of the model, and finally model and simulate the verification in the simulation software.

[0004] Another implementation method (method two) is to directly modify the antenna structure without adding an additional band-pass filtering network. By modifying the structure of the antenna, it is possible to make the antenna produce two kinds of radiation modes that can cancel each other at certain frequencies, and the radiation efficiency of the antenna at this frequency point is very low, so this point is also called the radiation zero point. As long as the frequency of the radiation zero point is reasonably adjusted to be close to the passband, a band-pass filtering response effect can be achieved. The main steps of this method are to first find a method to introduce a zero point, and then adjust the position of the zero point until an ideal filtering effect is obtained.

[0005] The main disadvantage of method one is that the volume is large, because in terms of volume, the design result is equivalent to a band-pass filter + antenna. Compared with the traditional cascaded structure, although it can avoid the loss caused by the transmission line matching network, its volume is still large, that is, this method only achieves the purpose of reducing the loss of the filtering antenna, but does not achieve the design goal of reducing the volume.

[0006] The main disadvantage of the method two is that it is difficult to ensure the consistency of the filter in all directions, because the radiation direction of the antenna has many angles, and when the radiation zero point is introduced, it is necessary to consider whether the antenna gain of each angle on the whole radiation pattern has the band-pass filtering effect. However, it is difficult to find two radiation modes that can offset each other in all directions, and the general implementation method cannot guarantee the filtering performance in all directions. SUMMARY

[0007] The purpose of the present application is to provide a filtering patch antenna with cross-polarization suppression, which aims to solve the above technical problems.

[0008] The present application is realized as follows: a filtering patch antenna with cross-polarization suppression, the filtering patch antenna with cross-polarization suppression comprises a patch radiator, a filtering feed structure and a ground plate, the lower surface of the filtering feed structure is connected with a coaxial line through the ground plate, the upper surface of the filtering feed structure is connected with the lower surface of the patch radiator, and the filtering feed structure is filtered and fed according to two C-shaped microstrip line networks.

[0009] A further technical solution of the present application is that the filtering feed structure comprises a first circuit layer, a dielectric layer and a second circuit layer, and the first circuit layer is connected with the second circuit layer through the dielectric layer.

[0010] A further technical solution of the present application is that a C-shaped microstrip line is arranged on the first circuit layer and the second circuit layer respectively.

[0011] A further technical solution of the present application is that the microstrip line comprises a first microstrip line, a second microstrip line, a third microstrip line, a first via hole, a second via hole and a metal probe, one end of the second microstrip line is connected with one end of the first microstrip line through the first via hole, the other end of the second microstrip line is connected with one end of the third microstrip line through the second via hole, and one end of the metal probe is connected with the second microstrip line.

[0012] A further technical solution of the present application is that the first via hole and the second via hole are located on the same side of the second microstrip line, the first via hole and the metal probe are located on different sides of the second microstrip line, and the other end of the first microstrip line is opposite to the other end of the third microstrip line.

[0013] A further technical solution of the present application is that the filtering feed structure utilizes the adjustment of the thickness of the dielectric layer, so that the energy can be effectively introduced into the upper layer at the passband frequency, and as the frequency decreases, the energy coupled to the upper layer is less and less.

[0014] The further technical scheme of the present application is that in the filter patch antenna, high frequency energy is suppressed by introducing a transmission zero point, source feed points are divided into two TEM waves on the circuit layer, when the path difference of the two TEM waves reaching the antenna feed point reaches the half wavelength of a certain frequency, the two TEM waves cancel each other out and the energy cannot be effectively fed into the antenna at the point to form a transmission zero point.

[0015] The beneficial effects of the present application are that the antenna is designed based on the feed structure, no additional filter network is introduced, so the volume of the filter antenna will not increase significantly, and even the overall volume can be maintained. The filtering characteristic is introduced from the feed structure, which fundamentally suppresses the energy radiation, and there is no need to consider whether the energy can be canceled in all directions. The filtering function can be realized without increasing the volume of the antenna, while ensuring the full direction consistency of the filtering, and the filter antenna also has the function of suppressing the cross polarization of the patch antenna, which is of great significance to improve the working performance of the antenna. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structure schematic diagram of the filter antenna fusion design.

[0017] Figure 2 is a schematic diagram of the filter patch antenna with cross polarization suppression provided by the embodiment of the present application.

[0018] Figure 3 is a 3D perspective view of the patch antenna structure provided by the embodiment of the present application.

[0019] Figure 4 is a structure side view of the patch antenna structure provided by the embodiment of the present application.

[0020] Figure 5 is a filter feed structure section view of the patch antenna structure provided by the embodiment of the present application.

[0021] Figure 6 is a simulation result schematic diagram of the radiation gain and reflection coefficient of the filter patch antenna provided by the embodiment of the present application.

[0022] Figure 7 is a schematic diagram of the relationship between the antenna radiation efficiency and the frequency provided by the embodiment of the present application.

[0023] Figure 8 is a cross polarization comparison schematic diagram of the patch antenna and the conventional probe feed method patch antenna provided by the embodiment of the present application. DETAILED DESCRIPTION

[0024] As Figure 2As shown, the filter patch antenna with cross-polarization suppression provided by the application comprises a patch radiator, a filter feed structure and a ground plate, the lower surface of the filter feed structure is connected with a coaxial line through the ground plate, the upper surface of the filter feed structure is connected with the lower surface of the patch radiator, and the filter feed structure is filtered and fed according to two C-shaped microstrip line networks.

[0025] The feed structure of a patch antenna is directly modified so that it feeds the patch antenna while having a band-pass filtering effect, that is, the functions of feeding and filtering are simultaneously considered. In terms of system volume, the overall volume of the design scheme only has a small increase or even no increase compared with the traditional patch antenna, because the feed structure is originally present in the antenna, and modifying it will not introduce too many devices and volume. In addition, the feed network itself has a band-pass filtering function, that is, energy can only be effectively fed into the antenna for radiation within the passband of the feed network, and the energy fed into the antenna is very small outside the passband. Since the energy fed into the antenna is weak, the energy radiated by the antenna is also greatly reduced. This energy reduction is relative to the omnidirectional direction, so the omnidirectional filtering response of the antenna has good consistency.

[0026] A structural diagram of a patch antenna integrated with a band-pass filter feed structure. The core structure of the antenna is a PCB (printed circuit board) plate located between the ground plate and the radiating patch, and the two C-shaped microstrip line networks on the PCB plate have filtering and feeding functions at the same time, which is a new type of filter feed network. Since only the feed structure is modified, the volume of the antenna is consistent with that of the traditional probe-fed patch antenna, and no increase is added.

[0027] In order to realize the filtering function, the feed structure should be able to simultaneously suppress the feeding of low-frequency and high-frequency energy into the antenna. The antenna designed in this paper uses a coupling feed method, from which the energy fed into the antenna is coupled to the feed structure through the patch radiator, and then the energy is filtered by the feed structure. Figures 3-5As can be seen from the antenna structure diagram, the line layer 2 and the line layer 3 are separated by a dielectric layer, and are not directly connected by a via or a microstrip line, so that as long as the thickness of the dielectric layer is properly adjusted, energy can be effectively fed to the upper layer at a passband frequency, and as the frequency decreases, the energy coupled to the upper layer becomes less and less, thereby forming a stopband. For the suppression of high-frequency energy, the transmission zero point can be introduced. The source feed point is divided into two TEM (transverse electromagnetic) waves on the line layer 4. When the wave path difference of the two TEM waves reaches half the wavelength of a certain frequency at the antenna feed point, the two waves will cancel each other out because of the phase difference of 180°, and energy cannot be effectively fed to the antenna at this point, thereby forming a transmission zero point. In addition, because there are two pairs of wave phase opposite vias in the feed structure, the length of the equivalent feed probe is shorter than that of the traditional probe-fed patch antenna, which is beneficial to the suppression of cross polarization.

[0028] The filter feed structure comprises a first line layer, a dielectric layer and a second line layer, and the first line layer is connected to the second line layer through the dielectric layer.

[0029] A C-shaped microstrip line is arranged on each of the first line layer and the second line layer.

[0030] The microstrip line comprises a first microstrip line, a second microstrip line, a third microstrip line, a first via, a second via and a metal probe. One end of the second microstrip line is connected to one end of the first microstrip line through the first via, the other end of the second microstrip line is connected to one end of the third microstrip line through the second via, and one end of the metal probe is connected to the second microstrip line.

[0031] The first via and the second via are located on the same side of the second microstrip line, the first via and the metal probe are located on different sides of the second microstrip line, and the other end of the first microstrip line is opposite to the other end of the third microstrip line.

[0032] The filter feed structure uses the adjustment of the thickness of the dielectric layer to enable energy to be effectively fed to the upper layer at a passband frequency, and as the frequency decreases, the energy coupled to the upper layer becomes less and less.

[0033] In the filter patch antenna, high-frequency energy is suppressed by introducing a transmission zero point. The source feed point is divided into two TEM waves on the line layer. When the wave path difference of the two TEM waves reaches half the wavelength of a certain frequency at the antenna feed point, the two TEM waves cancel each other out, and energy cannot be effectively fed to the antenna at this point, thereby forming a transmission zero point.

[0034] Figure 6The simulation results of the radiation gain (broadside direction, i.e. φ = 0°, θ = 0) and the reflection coefficient of the filter patch antenna are given. It can be seen from the simulation results that the filter antenna has obvious band-pass filtering characteristics, and the passband of the reflection coefficient is basically consistent with the passband of the radiation gain, the overlapping part is 2.3-2.6 GHz, which meets the working requirement of 2.4 GHz in the ISM frequency band, and has great practical application value.

[0035] In order to illustrate that the filter patch antenna of the present application has good omnidirectional filtering consistency, Figure 7 The schematic diagram of the relationship between the antenna radiation efficiency and the frequency is given, from which it can be seen that the radiation efficiency of the antenna also has obvious band-pass characteristics, which indicates that the energy of all the radiation directions has band-pass characteristics.

[0036] Finally, Figure 8 The cross polarization of the patch antenna is given in comparison with the cross polarization of the conventional probe-fed patch antenna, from which it can be seen that the cross polarization of the patch antenna is improved by about 6dB after the filter feeding network of the present application is used, and the improvement effect is very obvious.

[0037] Compared with the method one in the prior art, the design is based on the feeding structure of the antenna, and no additional filter network is introduced, so the volume of the filter antenna will not be greatly increased, and even the overall volume can be kept unchanged.

[0038] Compared with the method two in the prior art, since the filtering characteristics are introduced from the feeding structure, the energy radiation is fundamentally suppressed, so it is not necessary to consider whether the energy can be offset in all directions

[0039] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A filter patch antenna with cross-polarization suppression, characterized in that: The filter patch antenna with cross-polarization suppression includes a patch radiator, a filter feed structure and a ground plane, wherein the lower surface of the filter feed structure passes through the ground plane to be connected to the coaxial line, and the upper surface of the filter feed structure is connected to the lower surface of the patch radiator, and the filter feed structure performs filtering and feeding according to two C-shaped microstrip line networks; The filter feed structure includes a first circuit layer, a dielectric layer and a second circuit layer, and the first circuit layer is connected to the second circuit layer through the dielectric layer; A C-shaped microstrip line is provided on each of the first circuit layer and the second circuit layer; The C-shaped microstrip line includes a first microstrip line, a second microstrip line, a third microstrip line, a first via, a second via, and a metal probe, one end of the second microstrip line is connected to one end of the first microstrip line through the first via, the other end of the second microstrip line is connected to one end of the third microstrip line through the second via, and one end of the metal probe is connected to the second microstrip line; The first via hole and the second via hole are located on the same side of the second microstrip line, the first via hole and the metal probe are located on different sides of the second microstrip line, and the other end of the first microstrip line is opposite to the other end of the third microstrip line.

2. The filter patch antenna with cross-polarization suppression according to claim 1, characterized in that The filter feeding structure adjusts the thickness of the dielectric layer so that energy can be effectively fed into the upper layer at the passband frequency, and as the frequency decreases, the energy coupled to the upper layer becomes less and less.

3. The filter patch antenna with cross-polarization suppression according to claim 2, characterized in that In this filter patch antenna, high-frequency energy is suppressed by introducing a transmission zero point. The source feed point is divided into two TEM waves on the circuit layer. When the path difference between the two TEM waves reaching the antenna feed point reaches half the wavelength at a certain frequency, the two TEM waves cancel each other's energy at the certain frequency and cannot be effectively fed into the antenna to form a transmission zero point.

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