A broadband circularly polarized filter patch antenna

Abstract

The present invention discloses a broadband circularly polarized filter patch antenna, comprising upper and lower dielectric substrates. The upper dielectric substrate is printed with a main radiating patch, a vertical rectangular parasitic patch, a horizontal rectangular parasitic patch, and an L-shaped patch. The main radiating patch is loaded with a rectangular slot. 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, and the L-shaped patch is placed along the negative 45° diagonal of the main radiating patch. The lower dielectric substrate is printed with a floor and a microstrip feeder. A U-shaped slot is etched in the lower middle portion of the floor. Signals enter from a port, pass through the microstrip feeder, and are coupled to the main radiating patch through the U-shaped slot. The main radiating patch then couples and excites the surrounding parasitic patches. The broadband circularly polarized filter patch antenna provided by the present invention integrates circular polarization characteristics and bandpass filtering characteristics, achieving good impedance bandwidth and circular polarization bandwidth, and solving problems such as gain reduction and large size caused by the introduction of filtering circuits.

Description

Technical Field

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

[0002] Antennas are an integral part of wireless communication systems. As devices that transmit and receive electromagnetic waves, they play a crucial role in wireless communications. With the rapid development of mobile communication technology and various wireless systems, broadband circularly polarized filter patch antennas, which 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 advancement of drone and aerospace technology, the required range of antennas has expanded. Linearly polarized antennas are no longer able to meet these requirements. Circularly polarized antennas offer numerous advantages. Currently, linear polarization is commonly used in wireless communications, but a single polarization scheme is no longer sufficient for positioning and navigation. Circularly polarized antennas, in particular, offer advantages such as rain and fog resistance, multipath interference immunity, and high reception efficiency, leading to their widespread adoption in satellite navigation systems. Furthermore, antennas and filters are two of the most important components in RF front-end circuits, and their size and performance are crucial to overall system quality. Traditional design methods separate the antenna and filter, resulting in losses due to incomplete matching when cascaded. Integrating the antenna and filter into a filtered antenna not only combines both radiation and filtering characteristics, but also significantly reduces overall circuit size and unnecessary energy loss between components. Consequently, filtered circularly polarized antennas have become a hot topic of research for scholars both domestically and internationally.

[0004] Amidst the rapidly evolving communications technology landscape, researchers have proposed numerous approaches to integrating filter antennas with circularly polarized antennas, such as adding filter circuits to microstrip antennas. However, these approaches often suffer from significant drawbacks, most notably severe gain degradation and narrow bandwidth, making them difficult to meet the practical application requirements of communications systems. Therefore, it is necessary to design a new broadband circularly polarized filter patch antenna to address these issues. Summary of the Invention

[0005] The present invention aims to provide a broadband circularly polarized filtering 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 comprises an upper dielectric substrate and a lower dielectric substrate, wherein the lower dielectric substrate is located below the upper dielectric substrate, with an air gap between the upper and lower dielectric substrates. A main radiating 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 slot along the x-direction is loaded to the left of the center of the main radiating 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 a negative 45° diagonal of the main radiating 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 by the main radiation patch to the surrounding parasitic patches.

[0009] As a preferred embodiment of the present invention, there are two L-shaped patches of the same size. The L-shaped patches are L-shaped and are located between the vertical rectangular parasitic patch, the horizontal rectangular parasitic patch and the main radiation patch. The L-shaped patch includes 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 equal 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, for achieving 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. The transverse rectangular parasitic patches are rectangular in shape. 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 placed at the upper and lower edges of the upper dielectric substrate respectively 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 size is 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 placed at the left and right edges of the upper dielectric substrate along the y direction respectively. 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, with the left side 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, generating 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 ground at the starting end of the microstrip feeder.

[0017] The signal enters from the port, passes through the microstrip feed line, and is coupled to the main radiation patch through the U-shaped slot, and then is 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 advantages:

[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 generate a controllable radiation zero point by loading a pair of L-shaped metal patches between the main radiation patch and the parasitic patch placed in the horizontal direction so that the current on the L-shaped metal patch and the main radiation patch is reversed.

[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 radiating patch to produce circular polarization performance, but also form a reverse current in the vertical direction of the main radiating 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 produce a radiation null at low frequency, and then adjusts the length of the asymmetric U-shaped slot in the vertical direction to produce a radiation null at high frequency, thereby ultimately achieving 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 radiation zero points by adding a filtering network or superimposing structures in the vertical direction, so as to achieve a bandpass filtering response and a stable gain pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It 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 showing the simulation results of the S parameters and main polarization gain of the broadband circularly polarized filter patch antenna of this embodiment;

[0031] Figure 8 1 is a diagram showing the axial ratio simulation results of the broadband circularly polarized filter patch antenna of this embodiment;

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

[0033] Figure 101 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 2.78 GHz;

[0034] Figure 11 1 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] Figure 12 2. FIG. 4 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] Figure 13 2. FIG. 4 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] Figure 14 3.06 GHz is a simulation result diagram of the XOZ plane radiation pattern of the broadband circularly polarized filter patch antenna of this embodiment;

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

[0039] In the figure: 1. Upper dielectric substrate; 2. Rectangular slot; 3. Vertical rectangular parasitic patch; 3a. First vertical rectangular parasitic patch; 3b. Second vertical rectangular parasitic patch; 4. Horizontal rectangular parasitic patch; 4a. First horizontal rectangular parasitic patch; 4b. Second horizontal 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 slot; 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 clearly and completely described 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 should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying 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 direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0042] Please see 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. 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. 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. The main radiation patch 1 is loaded with a rectangular slot 2 along the x-direction at the center left position. 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. 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, and 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 by the main radiation patch 1 to excite the surrounding parasitic patches.

[0044] In this embodiment, the upper dielectric substrate 6 and the lower dielectric substrate 10 are made of the same material but with different thicknesses. The upper surface of the upper dielectric substrate 6 is provided with a main radiating patch 1, a vertical rectangular parasitic patch 3, a horizontal rectangular parasitic patch 4, and an L-shaped patch 5. A rectangular slot 2 along the x-direction is placed to the left of the center of the main radiating patch 1. The upper surface of the lower dielectric substrate 10 is printed with a floor plate 7, with a U-shaped slot 8 etched in the lower center of the floor plate 7. A microstrip feed line 9 is printed on the lower surface of the lower dielectric substrate 10. Signals enter through port 20, pass through the microstrip feed line 9, and are coupled to the main radiating patch 1 through the U-shaped slot 8. The main radiating patch 1 then couples and excites the surrounding parasitic patches. While maintaining a small device size, the integrated design combines circular polarization and bandpass filtering characteristics, achieving both good impedance bandwidth and circular polarization bandwidth, addressing issues such as gain reduction and large size caused by the introduction of filtering circuits.

[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 both 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 out 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. 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 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, there are two vertical rectangular parasitic patches 3 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 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, 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 another circularly polarized radiation frequency (2.98 GHz), 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. Adjusting the length of the U-shaped groove 8 in the vertical direction is used 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, generating a circularly polarized radiation frequency point.

[0055] In this embodiment, a floor panel 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 portion of the floor panel 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 radiating patch 1, thereby generating a controllable radiation zero point. By adjusting the vertical length of the asymmetric U-shaped groove 8, 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 radiating 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 ground plane 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 in 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, which makes the low frequency have a good out-of-band suppression effect from 2.5GHz above, and the high frequency has a good out-of-band suppression effect from 3.5GHz above, and obtains a good bandpass filtering response.

[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. The 2.78GHz is introduced by the asymmetric U-shaped groove etched on the floor, the 2.98GHz is generated by a pair of rectangular parasitic patches on the upper surface of the upper dielectric substrate, and the 3.06GHz is generated by a pair of rectangular parasitic patches on the lower surface of the upper dielectric substrate.

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

[0061] Figure 10-11 Figure 2 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 2.78 GHz. It can be seen that the circular polarization direction at this frequency point is right-hand circular polarization (RHCP);

[0062] Figure 12-13Figure 2 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 at this frequency point is right-hand circular polarization (RHCP);

[0063] Figure 14-15 Figure 2 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 at this frequency point is right-hand circular polarization (RHCP);

[0064] The present invention changes the ordinary 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 to generate a controllable radiation zero point. 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 to generate a radiation point at a high frequency, thereby achieving a bandpass filtering 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. The asymmetric U-shaped groove 8 etched on the floor and the two pairs of rectangular parasitic patches on the upper dielectric substrate 6 can respectively generate three circularly polarized radiation frequencies to 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 length of the two, a radiation zero point is generated at 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 embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A broadband circularly polarized filter patch antenna, characterized by: 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), and an air gap exists between the upper dielectric substrate (6) and the lower dielectric substrate (10); a main radiation patch (1), a vertical rectangular parasitic patch (3), a horizontal rectangular parasitic patch (4) and an L-shaped patch (5) are printed on the upper surface of the upper dielectric substrate (6); 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 x-direction of the upper dielectric substrate (6); the horizontal rectangular parasitic patch (4) is placed along the y-direction of the upper dielectric substrate (6); and the L-shaped patch (5) is placed along a negative 45° diagonal line 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 the main radiation patch (1) through the U-shaped groove (8), and then is coupled and excited by the main radiation patch (1) to the surrounding parasitic patches; The number of the L-shaped patches (5) is two and the sizes are the same. The shape of the L-shaped patches (5) is 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) is cut out of a rectangle of the same size on the upper and lower edges close to the first L-shaped patch (5a) for adjusting impedance matching. A rectangle of the same size is cut out at the inner corner of each of the first L-shaped patch (5a) and the second L-shaped patch (5b) to achieve 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; 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, the microstrip feed line (9) is coupled to the main radiation patch (1) through the U-shaped slot (8), thereby generating a circularly polarized radiation frequency point.

2. The broadband circularly polarized filter patch antenna according to claim 1, wherein: The number of the transverse rectangular parasitic patches (4) is two and the size is 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 transverse rectangular parasitic patches (4) are coupled through the main radiation patch (1) to generate a circularly polarized radiation frequency point.

3. The broadband circularly polarized filter patch antenna according to claim 1, wherein: 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 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 vertical rectangular parasitic patch (3) on the lower surface is coupled to the main radiation patch (1) to generate a circularly polarized radiation frequency point.

4. The broadband circularly polarized filter patch antenna according to claim 1, wherein: The microstrip feeder (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 feeder (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); and the port (20) is connected to the floor (8) at the starting end of the microstrip feeder (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 slot (8), and then is coupled and excited to the surrounding parasitic patches by the main radiation patch (1).

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