Broadband circularly polarized filtering patch antenna

Abstract

The invention discloses a broadband circularly polarized filtering patch antenna which comprises an upper dielectric substrate and a lower dielectric substrate, a main radiation patch, a vertical rectangular parasitic patch, a transverse rectangular parasitic patch and an L-shaped patch are printed on the upper dielectric substrate, a rectangular groove is loaded on the main radiation patch, the vertical rectangular parasitic patch is placed in the y direction of the upper dielectric substrate, and the transverse rectangular parasitic patch is placed in the L-shaped patch. The transverse rectangular parasitic patch is arranged along the x direction, and the L-shaped patch is arranged along the minus 45-degree diagonal line of the main radiation patch; a floor and a micro-strip feeder line are printed on the lower dielectric substrate, a U-shaped groove is etched in the lower middle portion of the floor, and signals enter from a port, pass through the micro-strip feeder line, are coupled to the main radiation patch through the U-shaped groove and then are coupled and excited to the peripheral parasitic patches through the main radiation patch. According to the broadband circularly polarized filtering patch antenna provided by the invention, the circularly polarized characteristic and the band-pass filtering characteristic are integrally designed, so that good impedance bandwidth and circularly polarized bandwidth are obtained, and the problems of gain reduction, large size and the like caused by introduction of a filtering circuit are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency communication, and in particular to a broadband circularly polarized filtering patch antenna. Background Art

[0002] Antennas are an indispensable part of wireless communication systems. As devices that transmit and receive electromagnetic waves, they play a vital role in wireless communication. With the rapid development of mobile communication technology and various wireless systems, broadband circularly polarized filter patch antennas that can significantly improve communication quality have gradually attracted widespread attention. Patch antennas are widely used due to their low profile, miniaturization, and low cost.

[0003] With the development of UAV technology and aerospace technology, the range that antennas need to cover has expanded. Linear polarization antennas can hardly meet the needs of applications. In comparison, circular polarization antennas have many advantages. At present, linear polarization working mode is commonly used in wireless communications, but a single polarization mode can no longer meet the needs of positioning and navigation. In particular, circular polarization antennas have the advantages of rain and fog protection, multipath interference resistance, and high receiving efficiency, so they are widely used in satellite navigation systems. At the same time, antennas and filters are the two most important components of RF front-end circuits, and their size and performance are crucial to the quality of the overall system. The traditional design method designs the antenna and filter separately, which causes the two devices to have a loss problem due to incomplete matching when cascaded. The filter antenna formed by integrating the antenna and the filter not only has both radiation characteristics and filtering characteristics, but also can greatly reduce the overall size of the circuit and unnecessary energy loss between devices. Therefore, the filter circular polarization antenna has also become a hot topic for domestic and foreign scholars.

[0004] In the context of the rapid changes in the communication technology era, researchers have proposed many solutions to integrate the design of filter antennas and circularly polarized antennas, such as loading filter circuits on microstrip antennas. However, these methods have more or less defects that cannot be ignored, the most obvious of which are serious gain reduction and too narrow bandwidth, which are difficult to meet the actual application requirements of communication systems. Therefore, it is necessary to design a new broadband circularly polarized filter patch antenna to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a broadband circularly polarized filter patch antenna to solve at least one technical problem existing in the above-mentioned prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A broadband circularly polarized filter patch antenna, comprising an upper dielectric substrate and a lower dielectric substrate, wherein the lower dielectric substrate is located below the upper dielectric substrate, an air gap exists between the upper dielectric substrate and the lower dielectric substrate, a main radiation patch, a vertical rectangular parasitic patch, a horizontal rectangular parasitic patch and an L-shaped patch are printed on the upper surface of the upper dielectric substrate, a rectangular groove along the x-direction is loaded at the middle left position of the main radiation patch, the vertical rectangular parasitic patch is placed along the y-direction of the upper dielectric substrate, the horizontal rectangular parasitic patch is placed along the x-direction of the upper dielectric substrate, and the L-shaped patch is placed along the negative 45° diagonal of the main radiation patch;

[0008] A floor is printed on the upper surface of the lower dielectric substrate, a U-shaped groove is etched in the middle and lower part of the floor, and a microstrip feeder is printed on the lower surface of the lower dielectric substrate. The signal enters from the port, passes through the microstrip feeder, and is coupled to the main radiation patch through the U-shaped groove, and then coupled and excited to the surrounding parasitic patches by the main radiation patch.

[0009] As a preferred embodiment of the present invention, there are two L-shaped patches with the same size. The shape of the L-shaped patches is L-shaped. The L-shaped patches are located between the vertical rectangular parasitic patches, the horizontal rectangular parasitic patches and the main radiation patches. The L-shaped patches include a first L-shaped patch and a second L-shaped patch. The first L-shaped patch and the second L-shaped patch are both made of metal. The first L-shaped patch and the second L-shaped patch are both placed along the negative 45° diagonal of the main radiation patch. The main radiation patch is close to the edge of the first L-shaped patch and has a rectangle of the same size cut out on the upper and lower sides for adjusting impedance matching.

[0010] As a preferred embodiment of the present invention, a rectangle of the same size is cut out from the inner corners of the first L-shaped patch and the second L-shaped patch respectively, so as to achieve impedance matching;

[0011] A radiation zero point is generated by the loaded L-shaped patch, and the length of the L-shaped patch is changed to control the radiation zero point.

[0012] As a preferred embodiment of the present invention, there are two transverse rectangular parasitic patches of the same size, and the shape of the transverse rectangular parasitic patches is rectangular. The transverse rectangular parasitic patches include a first transverse rectangular parasitic patch and a second transverse rectangular parasitic patch. The first transverse rectangular parasitic patch and the second transverse rectangular parasitic patch are symmetrically distributed about the center of the main radiation patch, and are respectively placed at the upper and lower edges of the upper dielectric substrate along the x-direction. The transverse rectangular parasitic patch is coupled with the main radiation patch to generate a circularly polarized radiation frequency point.

[0013] As a preferred embodiment of the present invention, the number of the vertical rectangular parasitic patches is two and the sizes are the same. The shape of the vertical rectangular parasitic patches is rectangular. The vertical rectangular parasitic patches include a first vertical rectangular parasitic patch and a second vertical rectangular parasitic patch. The first vertical rectangular parasitic patch and the second vertical rectangular parasitic patch are symmetrically distributed about the center of the main radiation patch and are respectively placed at the left and right edges of the upper dielectric substrate along the y direction. The length of the vertical rectangular parasitic patch on the lower surface is greater than that of the horizontal rectangular parasitic patch on the upper surface, and the width of the horizontal rectangular parasitic patch is greater than that of the vertical rectangular parasitic patch. The main radiation patch is coupled to the vertical rectangular parasitic patch on the lower surface to generate a circularly polarized radiation frequency point.

[0014] As a preferred embodiment of the present invention, the U-shaped groove is asymmetrically arranged, and the left side is shorter than the right side. The U-shaped groove generates a radiation zero point, and the length of the U-shaped groove in the vertical direction is adjusted to control the radiation zero point;

[0015] At the same time, through the U-shaped slot, the microstrip feed line is coupled to the main radiation patch via the U-shaped slot to generate a circularly polarized radiation frequency point.

[0016] As a preferred embodiment of the present invention, the microstrip feeder includes a first parallel branch, a second parallel branch, a third parallel branch and a fourth parallel branch. The first parallel branch, the second parallel branch and the third parallel branch loaded on the microstrip feeder are used to adjust impedance matching. The third parallel branch and the fourth parallel branch have the same shape and size. The width of the second parallel branch is greater than that of the third parallel branch and the fourth parallel branch. The port is connected to the floor at the starting end of the microstrip feeder.

[0017] The signal enters from the port, passes through the microstrip feed line, is coupled to the main radiation patch through the U-shaped slot, and is then coupled and excited to the surrounding parasitic patches by the main radiation patch.

[0018] Compared with the prior art, the broadband circularly polarized filter patch antenna provided by the present invention has the following beneficial effects:

[0019] 1. The antenna designed in the present invention etches an asymmetric U-shaped groove on the floor. The microstrip feed line is coupled to the main radiation patch through the groove, which can generate a circularly polarized radiation frequency point. A pair of rectangular parasitic patches loaded in the horizontal direction of the main radiation patch can generate a second circularly polarized radiation frequency point. Another pair of rectangular parasitic patches of different sizes loaded in the vertical direction of the main radiation patch can generate a third circularly polarized radiation frequency point, thereby achieving broadband circularly polarized radiation performance.

[0020] 2. The antenna designed by the present invention can make the current on the L-shaped metal patch and the main radiation patch reverse by loading a pair of L-shaped metal patches between the main radiation patch and the parasitic patch placed in the horizontal direction, thereby generating a controllable radiation zero point.

[0021] 3. The antenna designed by the present invention, through the asymmetric U-shaped groove etched on the floor, can not only be used to stimulate the main radiation patch to produce circular polarization performance, but also form a reverse current in the vertical direction of the main radiation patch to produce a controllable radiation zero point.

[0022] 4. The antenna designed by the present invention adjusts the length of the L-shaped metal patch to generate a radiation zero point at low frequency, and then adjusts the length of the asymmetric U-shaped slot in the vertical direction to generate a radiation zero point at high frequency, ultimately enabling the antenna to achieve broadband circularly polarized radiation performance with good bandpass filtering response.

[0023] Compared with other antennas, the antenna designed in the present invention has a wider axial ratio bandwidth, and does not need to generate a radiation zero point by adding a filtering network or superimposing a structure in the vertical direction, so as to achieve a bandpass filtering response, and the gain radiation pattern is stable and good. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a structural schematic diagram of the antenna structure of the present invention;

[0025] Figure 2 is a side view of the antenna structure of the present invention;

[0026] Figure 3 is a top view of the upper dielectric substrate;

[0027] Figure 4 is a bottom view of the upper dielectric substrate;

[0028] Figure 5 is a top view of the lower dielectric substrate;

[0029] Figure 6 is a bottom view of the lower dielectric substrate;

[0030] Figure 7 1 is a diagram of simulation results of S parameters and main polarization gain of the broadband circularly polarized filter patch antenna of this embodiment;

[0031] Figure 8 is a diagram of the simulation results of the axial ratio of the broadband circularly polarized filter patch antenna of this embodiment;

[0032] Fig. 9 1 is a simulation result diagram of the main polarization and cross-polarization gain of the broadband circularly polarized filter patch antenna of this embodiment varying with frequency;

[0033] Fig.10is a simulation result diagram of the XOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 2.78 GHz;

[0034] Fig.11 is a simulation result diagram of the YOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 2.78 GHz;

[0035] Fig.12 is a simulation result diagram of the XOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 2.98 GHz;

[0036] Fig.13 is a simulation result diagram of the YOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 2.98 GHz;

[0037] Fig.14 3 is a simulation result diagram of the XOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 3.06 GHz;

[0038] Fig.15 3 is a simulation result diagram of the YOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 3.06 GHz;

[0039] In the figure: 1. upper dielectric substrate; 2. rectangular groove; 3. vertical rectangular parasitic patch; 3a. first vertical rectangular parasitic patch; 3b. second vertical rectangular parasitic patch; 4. transverse rectangular parasitic patch; 4a. first transverse rectangular parasitic patch; 4b. second transverse rectangular parasitic patch; 5. L-shaped patch; 5a. first L-shaped patch; 5b. second L-shaped patch; 6. upper dielectric substrate; 7. floor; 8. U-shaped groove; 9. microstrip feeder; 9a. first parallel branch; 9b. second parallel branch; 9c. third parallel branch; 9d. fourth parallel branch; 10. lower dielectric substrate; 20. port. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0042] Please refer to the attached Figure 1-6 As shown, this embodiment provides a broadband circularly polarized filter patch antenna including an upper dielectric substrate 6 and a lower dielectric substrate 10, wherein the lower dielectric substrate 10 is located below the upper dielectric substrate 6, and there is an air gap between the upper dielectric substrate 6 and the lower dielectric substrate 10, and the upper surface of the upper dielectric substrate 6 is printed with a main radiation patch 1, a vertical rectangular parasitic patch 3, a horizontal rectangular parasitic patch 4 and an L-shaped patch 5, and a rectangular groove 2 along the x-direction is loaded at the middle left position of the main radiation patch 1, the vertical rectangular parasitic patch 3 is placed along the y-direction of the upper dielectric substrate 6, the horizontal rectangular parasitic patch 4 is placed along the x-direction of the upper dielectric substrate 6, and the L-shaped patch 5 is placed along the negative 45° diagonal of the main radiation patch 1;

[0043] A floor 7 is printed on the upper surface of the lower dielectric substrate 10, a U-shaped groove 8 is etched in the middle and lower part of the floor 7, and a microstrip feed line 9 is printed on the lower surface of the lower dielectric substrate 10. The signal enters from the port 20, passes through the microstrip feed line 9, and is coupled to the main radiation patch 1 through the U-shaped groove 8, and then is coupled and excited to the surrounding parasitic patches by the main radiation patch 1.

[0044] In this embodiment, the upper dielectric substrate 6 and the lower dielectric substrate 10 are dielectric substrates of the same material but different thicknesses. The upper surface of the upper dielectric substrate 6 is provided with a main radiation patch 1, a vertical rectangular parasitic patch 3, a horizontal rectangular parasitic patch 4 and an L-shaped patch 5. A rectangular groove 2 along the x direction is loaded at the middle left position of the main radiation patch 1. The upper surface of the lower dielectric substrate 10 is printed with a floor 7. A U-shaped groove 8 is etched in the middle and lower part of the floor 7. A microstrip feed line 9 is printed on the lower surface of the lower dielectric substrate 10. The signal enters from the port 20, passes through the microstrip feed line 9, and is coupled to the main radiation patch 1 through the U-shaped groove 8, and then is coupled and excited to the surrounding parasitic patches by the main radiation patch 1. While ensuring that the device size is small, the circular polarization characteristics and the bandpass filtering characteristics are integrated into a design, and good impedance bandwidth and circular polarization bandwidth are obtained at the same time, solving the problems of gain reduction and large size caused by the introduction of the filter circuit.

[0045] An optional implementation method, such as Figure 1-3As shown, the number of the L-shaped patches 5 is two and the size is the same. The shape of the L-shaped patch 5 is L-shaped. The L-shaped patch 5 is located between the vertical rectangular parasitic patch 3, the horizontal rectangular parasitic patch 4 and the main radiation patch 1. The L-shaped patch 5 includes a first L-shaped patch 5a and a second L-shaped patch 5b. The first L-shaped patch 5a and the second L-shaped patch 5b are both made of metal. The first L-shaped patch 5a and the second L-shaped patch 5b are placed along the negative 45° diagonal of the main radiation patch 1. The main radiation patch 1 is close to the edge of the first L-shaped patch 5a and cuts off a rectangle of the same size on the upper and lower sides for adjusting impedance matching.

[0046] An optional implementation method, such as Figure 1-3 As shown, a rectangle of the same size is cut out from the inner corners of the first L-shaped patch 5a and the second L-shaped patch 5b respectively, for achieving impedance matching;

[0047] A radiation zero point is generated by the loaded L-shaped patch 5, and the length of the L-shaped patch 5 is changed to control the radiation zero point.

[0048] In this embodiment, a controllable radiation zero point is generated by the loaded L-shaped patch 5, and a radiation zero point is generated at a low frequency by adjusting the length of the L-shaped metal patch.

[0049] An optional implementation method, such as Figure 1-3 As shown, there are two transverse rectangular parasitic patches 4 of the same size, and the shape of the transverse rectangular parasitic patches 4 is rectangular. The transverse rectangular parasitic patches 4 include a first transverse rectangular parasitic patch 4a and a second transverse rectangular parasitic patch 4b. The first transverse rectangular parasitic patch 4a and the second transverse rectangular parasitic patch 4b are symmetrically distributed about the center of the main radiation patch 1, and are respectively placed at the upper and lower edges of the upper dielectric substrate 6 along the x direction. The transverse rectangular parasitic patch 4 is coupled through the main radiation patch 1 to generate a circularly polarized radiation frequency point.

[0050] In this embodiment, a pair of transverse rectangular parasitic patches 4 of the same size are printed on the upper surface of the upper dielectric substrate 6. The two transverse rectangular parasitic patches 4 are symmetrically distributed about the center of the main radiation patch 1 and are placed at the upper and lower edges of the upper dielectric substrate 6 along the x-direction. The main radiation patch 1 is coupled to the transverse rectangular parasitic patch 5 to generate the first circularly polarized radiation frequency (2.98 GHz).

[0051] An optional implementation method, such as Figure 1-4As shown, the number of the vertical rectangular parasitic patches 3 is two and the sizes are the same. The shape of the vertical rectangular parasitic patches 3 is rectangular. The vertical rectangular parasitic patches 3 include a first vertical rectangular parasitic patch 3a and a second vertical rectangular parasitic patch 3b. The first vertical rectangular parasitic patch 3a and the second vertical rectangular parasitic patch 3b are symmetrically distributed about the center of the main radiation patch 1 and are respectively placed at the left and right edges of the upper dielectric substrate 6 along the y direction. The length of the vertical rectangular parasitic patch 3 on the lower surface is greater than that of the horizontal rectangular parasitic patch 4 on the upper surface. The width of the horizontal rectangular parasitic patch 4 is greater than that of the vertical rectangular parasitic patch 3. The main radiation patch 1 is coupled to the vertical rectangular parasitic patch 3 on the lower surface to generate a circularly polarized radiation frequency point.

[0052] In this embodiment, by coupling the main radiation patch 1 to a pair of vertical rectangular parasitic patches 3 placed along the x direction on the upper surface and a pair of horizontal rectangular parasitic patches 4 placed along the y direction on the lower surface, another circularly polarized radiation frequency point (2.98 GHz) can be generated respectively, thereby broadening the axial ratio bandwidth and achieving broadband performance.

[0053] An optional implementation method, such as Figure 1-6 As shown, the U-shaped groove 8 is asymmetrically arranged, and the left side is shorter than the right side. The U-shaped groove 8 generates a radiation zero point, and the length of the U-shaped groove 8 in the vertical direction is adjusted to control the radiation zero point;

[0054] At the same time, through the U-shaped slot 8, the microstrip feed line 9 is coupled to the main radiation patch 1 via the U-shaped slot 8 to generate a circularly polarized radiation frequency point.

[0055] In this embodiment, a floor 7 is printed on the upper surface of the lower dielectric substrate 10, and an asymmetric U-shaped groove 8 is etched in the lower middle of the floor 7. The left side of the asymmetric U-shaped groove 8 is shorter than the right side. The asymmetric U-shaped groove 8 can form a reverse current in the vertical direction of the main radiation patch 1, thereby generating a controllable radiation zero point. By adjusting the length of the asymmetric U-shaped groove 8 in the vertical direction, the radiation zero point can be located at a high frequency. At the same time, through the asymmetric U-shaped groove 8, the microstrip feed line 9 is coupled to the main radiation patch through the groove, thereby generating a third circularly polarized radiation frequency point (2.78 GHz).

[0056] An optional implementation method, such as Figure 1-6As shown, the microstrip feed line 9 includes a first parallel branch 9a, a second parallel branch 9b, a third parallel branch 9c and a fourth parallel branch 9d. The first parallel branch 9a, the second parallel branch 9b and the third parallel branch 9c loaded on the microstrip feed line 9 are used to adjust impedance matching. The third parallel branch 9c and the fourth parallel branch 9d have the same shape and size. The width of the second parallel branch 9b is greater than that of the third parallel branch and the fourth parallel branch 9d. The port 20 is connected to the floor 8 at the starting end of the microstrip feed line 10;

[0057] The signal enters from the port 20, passes through the microstrip feed line 9, and is coupled to the main radiation patch 1 through the U-shaped slot 8, and then is coupled and excited to the surrounding parasitic patches by the main radiation patch 1.

[0058] Figure 7 This is a simulation result diagram of the S parameters and main polarization gain of the broadband circularly polarized filter patch antenna of this embodiment. The frequency band where the S parameter is lower than -10dB is 2.69-3.35GHz (21.85%), a radiation zero point in the low-frequency stop band is 2.0GHz, and a radiation zero point in the high-frequency stop band is 3.67GHz, so that the low frequency has a good out-of-band suppression effect from 2.5GHz upwards, and the high frequency also has a good out-of-band suppression effect from 3.5GHz upwards, and a good bandpass filtering response is obtained.

[0059] Figure 8 This is a diagram of the axial ratio simulation results of the broadband circularly polarized filter patch antenna in this embodiment. The axial ratio bandwidth below -3dB is 2.71GHz-3.08GHz (12.78%), and the three axial ratio frequencies are 2.78GHz, 2.98GHz and 3.06GHz, respectively. 2.78GHz is introduced by the asymmetric U-shaped groove etched on the floor, 2.98GHz is generated by a pair of rectangular parasitic patches on the upper surface of the upper dielectric substrate, and 3.06GHz is generated by a pair of rectangular parasitic patches on the lower surface of the upper dielectric substrate.

[0060] Fig. 9 3 is a simulation result diagram of the main polarization and cross-polarization gain of the broadband circularly polarized filter patch antenna of this embodiment varying with frequency. It can be seen that there is good cross-polarization within the axial ratio bandwidth.

[0061] Figure 10-11 2 is a simulation result diagram of the XOZ plane and YOZ plane directional diagram of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 2.78 GHz. It can be seen that the circular polarization direction of this frequency point is right-hand circular polarization (RHCP);

[0062] Figure 12-132 is a simulation result diagram of the XOZ plane and YOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 2.98 GHz. It can be seen that the circular polarization direction of this frequency point is right-hand circular polarization (RHCP);

[0063] Figure 14-15 3 is a simulation result diagram of the XOZ plane and YOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment at a frequency of 3.06 GHz. It can be seen that the circular polarization direction of this frequency point is right-hand circular polarization (RHCP);

[0064] The present invention changes the common slot into an asymmetric U-shaped slot 8 on the basis of a broadband circularly polarized patch antenna, thereby generating a circularly polarized radiation frequency point and a controllable radiation zero point at the same time; the main radiation patch 1 is coupled to a pair of vertical rectangular parasitic patches 3 placed along the x direction on the upper surface and a pair of horizontal rectangular parasitic patches 4 placed along the y direction on the lower surface, thereby generating a circularly polarized radiation frequency point respectively, broadening the axial ratio bandwidth and achieving broadband performance; and then a pair of L-shaped metal patches of equal size are loaded between the main radiation patch 2 and the rectangular parasitic patch, thereby generating a controllable radiation zero point, and by adjusting the length of the L-shaped metal patch, a radiation zero point is generated at a low frequency, and then the length of the asymmetric U-shaped slot 8 in the vertical direction is adjusted, so that a radiation point is generated at a high frequency, thereby achieving a bandpass filter response while achieving broadband.

[0065] In summary, the present invention utilizes the advantages of low profile and small size of the patch antenna to achieve miniaturization. An asymmetric U-shaped groove 8 is etched on the floor, and two pairs of rectangular parasitic patches are formed on the upper dielectric substrate 6, which can respectively generate three circularly polarized radiation frequencies and achieve broadband circular polarization performance. The asymmetric U-shaped groove 8 and a pair of L-shaped metal patches can respectively generate two radiation zero points. By adjusting the lengths of the two, a radiation zero point is generated at the high and low frequencies respectively, thereby achieving a bandpass filtering response and solving the problems of gain reduction and large size caused by the introduction of the filtering circuit.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A broadband circularly polarized filter patch antenna, characterized in that: The invention comprises an upper dielectric substrate (6) and a lower dielectric substrate (10), wherein the lower dielectric substrate (10) is located below the upper dielectric substrate (6), an air gap exists between the upper dielectric substrate (6) and the lower dielectric substrate (10), and the upper surface of the upper dielectric substrate (6) is printed with a main radiation patch (1), a vertical rectangular parasitic patch (3), a horizontal rectangular parasitic patch (4) and an L-shaped patch (5), wherein a rectangular groove (2) along the x-direction is loaded at a position slightly to the left of the center of the main radiation patch (1), the vertical rectangular parasitic patch (3) is placed along the y-direction of the upper dielectric substrate (6), the horizontal rectangular parasitic patch (4) is placed along the x-direction of the upper dielectric substrate (6), and the L-shaped patch (5) is placed along the negative 45° diagonal of the main radiation patch (1); A floor (7) is printed on the upper surface of the lower dielectric substrate (10), a U-shaped groove (8) is etched in the middle and lower part of the floor (7), and a microstrip feed line (9) is printed on the lower surface of the lower dielectric substrate (10). A signal enters from a port (20), passes through the microstrip feed line (9), and is coupled to a main radiation patch (1) through the U-shaped groove (8), and then is coupled and excited by the main radiation patch (1) to surrounding parasitic patches.

2. A broadband circularly polarized filter patch antenna according to claim 1, characterized in that: The number of the L-shaped patches (5) is two and they are of the same size. The L-shaped patches (5) are L-shaped. The L-shaped patches (5) are located between the vertical rectangular parasitic patch (3), the horizontal rectangular parasitic patch (4) and the main radiation patch (1). The L-shaped patches (5) include a first L-shaped patch (5a) and a second L-shaped patch (5b). The first L-shaped patch (5a) and the second L-shaped patch (5b) are both made of metal. The first L-shaped patch (5a) and the second L-shaped patch (5b) are both placed along the negative 45° diagonal of the main radiation patch (1). The main radiation patch (1) has a rectangle of the same size cut out at the upper and lower edges close to the first L-shaped patch (5a) for adjusting impedance matching.

3. A broadband circularly polarized filter patch antenna according to claim 2, characterized in that: A rectangle of the same size is cut out at the inner corners of the first L-shaped patch (5a) and the second L-shaped patch (5b) respectively, for achieving impedance matching; A radiation zero point is generated by the loaded L-shaped patch (5), and the length of the L-shaped patch (5) is changed to control the radiation zero point.

4. The broadband circularly polarized filter patch antenna according to claim 1, characterized in that: The number of the transverse rectangular parasitic patches (4) is two and the sizes are the same. The transverse rectangular parasitic patches (4) are rectangular in shape. The transverse rectangular parasitic patches (4) include a first transverse rectangular parasitic patch (4a) and a second transverse rectangular parasitic patch (4b). The first transverse rectangular parasitic patch (4a) and the second transverse rectangular parasitic patch (4b) are symmetrically distributed about the center of the main radiation patch (1) and are respectively placed at the upper and lower edges of the upper dielectric substrate (6) along the x-direction. The main radiation patch (1) is coupled to the transverse rectangular parasitic patch (4) to generate a circularly polarized radiation frequency point.

5. The broadband circularly polarized filter patch antenna according to claim 1, characterized in that: The number of the vertical rectangular parasitic patches (3) is two and they are of the same size. The vertical rectangular parasitic patches (3) are rectangular in shape. The vertical rectangular parasitic patches (3) include a first vertical rectangular parasitic patch (3a) and a second vertical rectangular parasitic patch (3b). The first vertical rectangular parasitic patch (3a) and the second vertical rectangular parasitic patch (3b) are symmetrically distributed about the center of the main radiation patch (1) and are respectively placed at the left and right edges of the upper dielectric substrate (6) along the y direction. The length of the vertical rectangular parasitic patch (3) on the lower surface is greater than that of the transverse rectangular parasitic patch (4) on the upper surface. The width of the transverse rectangular parasitic patch (4) is greater than that of the vertical rectangular parasitic patch (3). The main radiation patch (1) is coupled to the vertical rectangular parasitic patch (3) on the lower surface to generate a circularly polarized radiation frequency point.

6. The broadband circularly polarized filter patch antenna according to claim 1, characterized in that: The U-shaped groove (8) is asymmetrically arranged, and the left side is shorter than the right side. The U-shaped groove (8) generates a radiation zero point, and the length of the U-shaped groove (8) in the vertical direction is adjusted to control the radiation zero point; At the same time, through the U-shaped slot (8), the microstrip feed line (9) is coupled to the main radiation patch (1) via the U-shaped slot (8), thereby generating a circularly polarized radiation frequency point.

7. The broadband circularly polarized filter patch antenna according to claim 1, characterized in that: The microstrip feed line (9) comprises a first parallel branch (9a), a second parallel branch (9b), a third parallel branch (9c) and a fourth parallel branch (9d); the first parallel branch (9a), the second parallel branch (9b) and the third parallel branch (9c) loaded on the microstrip feed line (9) are used to adjust impedance matching; the third parallel branch (9c) and the fourth parallel branch (9d) have the same shape and the same size; the second parallel branch (9b) is wider than the third parallel branch and the fourth parallel branch (9d); the port (20) is connected to the floor (8) at the starting end of the microstrip feed line (10); The signal enters from the port (20), passes through the microstrip feed line (9), is coupled to the main radiation patch (1) through the U-shaped slot (8), and is then coupled and excited by the main radiation patch (1) to the surrounding parasitic patches.

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