Cavity-backed butterfly antenna

Abstract

The invention belongs to the technical field of antennas, and relates to a cavity-backed butterfly antenna, which comprises a cavity-backed structure and a butterfly structure, the back cavity structure comprises a supporting layer and a matching layer connected with the supporting layer; the supporting layer comprises a bottom plate and four side plates connected with the bottom plate to form a box-shaped structure; the matching layer and the bottom plate are arranged at an interval, and the matching layer is connected with more than one side plate; through holes are formed in the bottom plate and the matching layer to form a matching opening; the butterfly-shaped structure comprises a main board and a balun connected with the main board; the butterfly-shaped structure and the back cavity structure are arranged at intervals, the mainboard is arranged on one side of the matching layer, and the Balun penetrates through the matching port and then is connected with the input end, so that the back cavity type butterfly antenna is formed. By adopting the antenna, the performance characteristics of high gain, ultra wide band and miniaturization can be realized.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a cavity-backed butterfly antenna. Background Art

[0002] With the continuous advancement of urbanization, ground penetrating radar has received widespread attention due to its non-destructive detection capabilities and is widely used in pipeline detection, cavity detection, archaeological engineering and other fields. The ground penetrating radar antenna is an important component of the ground penetrating radar. The working performance of the ground penetrating radar antenna directly determines the detection depth and resolution of the system.

[0003] Since high-frequency electromagnetic waves have high losses, poor penetration, and shallow detection distance in lossy media, they are not suitable for deep detection applications of ground-penetrating radar. Therefore, the operating frequency of the current mainstream ground-penetrating radar antenna is basically below 1GHz. According to antenna design theory, the operating frequency of the antenna is related to the physical size of the antenna. The larger the physical size of the antenna, the lower the operating frequency. Conversely, the smaller the physical size of the antenna, the higher the operating frequency.

[0004] In summary, the convenience and detection capabilities of traditional antenna designs are insufficient in actual use, and at the same time, new requirements are put forward for the miniaturization of antennas. Summary of the invention

[0005] Based on this, it is necessary to provide a cavity-backed butterfly antenna to address the above technical problems, which can achieve the performance characteristics of high gain, ultra-wideband and miniaturization.

[0006] A cavity-backed butterfly-shaped antenna, comprising: a cavity-backed structure and a butterfly-shaped structure;

[0007] The back cavity structure comprises: a supporting layer and a matching layer connected to the supporting layer; the supporting layer comprises a bottom plate and four side plates connected to the bottom plate to form a box-shaped structure; the matching layer is spaced apart from the bottom plate and connected to one or more side plates; through holes are provided on the bottom plate and the matching layer to form a matching port;

[0008] The butterfly structure includes: a main board and a balun connected to the main board;

[0009] The butterfly structure is spaced apart from the back cavity structure, the main board is arranged at one side of the matching layer, and the balun is connected to the input end after passing through the matching port to form a back cavity type butterfly antenna.

[0010] In one embodiment, among the four side panels, two opposite side panels have the same height, and two adjacent side panels have different heights.

[0011] In one embodiment, the bottom plate is a rectangular structure, the height of the two side plates connected to the long sides of the bottom plate is less than the height of the other two side plates, and the two side plates connected to the short sides of the bottom plate are flush with the top surface of the main board.

[0012] In one embodiment, the matching layer includes: a matching substrate and a plurality of matching units disposed on the matching substrate;

[0013] There are gaps between adjacent matching units, and a plurality of matching units are arranged in an array to form a rectangular matching array.

[0014] In one embodiment, the matching substrate has the same length and width as the bottom plate.

[0015] In one embodiment, the mainboard includes: a mainboard dielectric board of a rectangular plate structure and two circular radiation patches symmetrically arranged on the bottom surface of the mainboard dielectric board;

[0016] The balun comprises: a balun dielectric plate of a rectangular plate structure and two wires respectively arranged on two sides of the balun dielectric plate; along the length direction of the balun, one end is a signal end and the other end is a connection end;

[0017] The connection end of the balun is vertically arranged at the bottom center of the mainboard, the symmetry axis of the connection end in the length direction is collinear with the symmetry axis of the bottom of the mainboard dielectric board in the width direction, and two conductors are respectively connected to a radiation patch to form an ultra-wideband antenna.

[0018] In one embodiment, the radiation patch is provided with a plurality of strip-shaped gaps;

[0019] A plurality of strip-shaped gaps are symmetrically spaced on both sides of a symmetry axis in the length direction of the bottom of the mainboard dielectric board; one end of the strip-shaped gap is arranged at a position at the edge of the radiation patch toward the corner of the mainboard dielectric board, and the other end extends toward the bottom center of the mainboard dielectric board, so that the strip-shaped gap is not arranged perpendicularly to the symmetry axis in the length direction of the bottom of the mainboard dielectric board.

[0020] In one embodiment, on the same radiation patch, the strip-shaped slots on the same side are arranged in parallel with equal intervals, and the distance between adjacent strip-shaped slots is 6 to 7 times the width of the strip-shaped slot.

[0021] In one embodiment, in the same radiation patch, the length of the strip-shaped slots on the same side gradually decreases in a direction away from the center of the main dielectric board.

[0022] In one embodiment, a loading resistor is provided on the edge of the radiation patch at a position corresponding to the other end of each strip-shaped gap, and there is a gap between adjacent loading resistors.

[0023] The above-mentioned cavity-backed butterfly antenna is designed with a cavity-backed structure for improving the forward gain of the antenna (wherein the supporting layer is used to support the matching layer, and the matching layer is used to change the phase of the backward radiated wave when it reaches the antenna radiating surface and reduce the cross-sectional height) and a butterfly structure with ultra-wideband radiation characteristics (wherein the main board is used to constitute the radiating body of the butterfly antenna, and the balun is used to achieve impedance matching and balanced and unbalanced conversion), so that the cavity-backed butterfly antenna has both high gain and ultra-wideband performance characteristics, ensures the effectiveness of signal transmission and reception, and reduces the volume and mass, achieves miniaturization, and improves portability; the cavity-backed structure and the butterfly structure are spaced apart to improve the forward gain, low-frequency gain and low-frequency bandwidth, achieve a low profile, and ensure good directivity; the matching substrate and the bottom plate are spaced apart to optimize the S11 parameters and reduce the metal cavity-backed structure. Increased current reflection; there is a gap between the balun and the edge of the matching port to reduce the mutual coupling effect between the balun and the back cavity structure to ensure radiation uniformity; the matching substrate is a plate-like structure and has the same length and width as the bottom plate to make the back reflection radiate uniformly to ensure the consistency of the influence of the back radiation electromagnetic wave; the balun is vertically arranged in the middle of the mainboard, and two symmetrical circular radiation patches are arranged on the bottom surface of the mainboard dielectric board as antenna arms, and a plurality of inclined strip gaps and loading resistors are designed on the antenna arms to achieve ultra-wideband, and to achieve compactness and miniaturization; the operating frequency of the antenna in this embodiment is 0.32~0.98GHz, which can achieve high gain, ultra-wideband and miniaturization performance characteristics, can be widely used in scenes such as ground penetrating radar, and is of great significance for achieving high resolution and high precision ground penetrating radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A three-dimensional schematic diagram of a cavity-backed butterfly antenna in one embodiment;

[0025] Figure 2 A schematic diagram of a support layer of a cavity-backed butterfly antenna in one embodiment;

[0026] Figure 3 A schematic diagram of a matching layer of a cavity-backed butterfly antenna in one embodiment;

[0027] Figure 4 A schematic diagram of a butterfly structure of a cavity-backed butterfly antenna in one embodiment;

[0028] Figure 5 A schematic diagram of a mainboard of a cavity-backed butterfly antenna in one embodiment;

[0029] Figure 6 A schematic diagram of a balun of a cavity-backed butterfly antenna in one embodiment;

[0030] Figure 7It is an S parameter simulation diagram of different side panels of a cavity-backed butterfly antenna in one embodiment;

[0031] Figure 8 A gain simulation diagram of different side panels of a cavity-backed butterfly antenna in one embodiment;

[0032] Fig. 9 A simulation diagram of impedance characteristics of a cavity-backed butterfly antenna in one embodiment;

[0033] Fig.10 A return loss simulation diagram of a cavity-backed butterfly antenna in one embodiment;

[0034] Fig.11 A measured return loss diagram of a cavity-backed butterfly antenna in one embodiment;

[0035] Fig.12 A simulation diagram of the +Z direction gain of a cavity-backed butterfly antenna in one embodiment;

[0036] Fig.13 A measured graph of the +Z direction gain of a cavity-backed butterfly antenna in one embodiment;

[0037] Fig.14 The E-plane radiation pattern of a cavity-backed butterfly antenna at 0.4 GHz in one embodiment;

[0038] Fig.15 Schematic diagram of the H-plane radiation pattern of a cavity-backed butterfly antenna at 0.4 GHz in one embodiment.

[0039] Reference numerals:

[0040] Back cavity structure 1;

[0041] Support layer 11, bottom plate 111, side plate 112;

[0042] Matching layer 12, matching substrate 121, matching unit 122, matching port 123;

[0043] Butterfly structure 2;

[0044] Main board 21, main board dielectric board 211, radiation patch 212;

[0045] Balun 22 , balun dielectric board 221 , wire 222 . DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0047] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0048] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0049] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0051] The present application provides a cavity-backed butterfly antenna, such as Figures 1 to 6 As shown, in one embodiment, it includes: a back cavity structure and a butterfly structure.

[0052] The back cavity structure includes: a supporting layer and a matching layer.

[0053] The supporting layer includes a bottom plate and four side plates. The bottom plate and the side plates are both rectangular plate structures. The four side plates are respectively vertically connected to one side of the bottom plate to form a box-shaped structure of the supporting layer.

[0054] The matching layer includes a matching substrate and a plurality of matching units. The matching substrate is a plate-like structure and has the same length and width as the base plate. The matching units are arranged on the matching substrate and the plurality of matching units are arranged in an array with gaps (i.e., there are gaps between adjacent matching units and the plurality of matching units are arranged in an array with equal gaps), so that the plurality of matching units form a rectangular matching array.

[0055] The supporting layer is connected to the matching layer. Specifically, the matching substrate is spaced apart from the bottom plate and connected to one or more side plates (the specific connection method belongs to the prior art and will not be repeated here, for example, connected through a fixing plate); through holes are provided on the matching layer and the bottom plate to form a matching port.

[0056] The butterfly structure includes: a main board and a balun.

[0057] The mainboard includes a mainboard dielectric board and two radiation patches. The mainboard dielectric board is a rectangular plate structure. The two radiation patches are both circular structures and are symmetrically arranged on both sides of the bottom surface of the mainboard dielectric board to serve as radiation arms of the antenna.

[0058] The balun includes a balun dielectric board and two wires. The balun dielectric board is a rectangular plate structure, and the two wires are respectively arranged on the two sides of the balun dielectric board; along the length direction of the balun, one end is the signal end for signal input, and the other end is the connection end for connecting to the mainboard.

[0059] The mainboard is connected to the balun. Specifically, the connection end of the balun is vertically arranged at the bottom center of the mainboard (specifically, a balun slot is provided in the center of the mainboard dielectric board, and the width of the balun slot is slightly larger than the thickness of the balun (for example: the width of the balun slot is 0.1 mm larger than the thickness of the balun), so that the balun is vertically connected to the mainboard through the balun slot), the symmetry axis in the length direction of the connection end is colinear with the symmetry axis in the width direction of the bottom of the mainboard dielectric board, and the two wires are respectively connected to a radiation patch (to provide a balanced input for the butterfly antenna and avoid affecting the performance of the antenna, specifically, solder can be used) to form an ultra-wideband antenna.

[0060] The back cavity structure and the butterfly structure are spaced apart, the main board is arranged on one side of the matching layer and the main board and the matching layer are spaced apart (that is, the matching layer is arranged between the supporting layer and the main board), the balun passes through the matching port and extends to the bottom of the back cavity structure and is connected to the input end (the specific connection method belongs to the prior art and will not be repeated here), and there is a gap between the balun and the edge of the matching port to form a back cavity type butterfly antenna.

[0061] It should be noted that the supporting layer, the matching unit of the matching layer, the radiation patch of the mainboard and the wires of the balun are all made of metal materials, and the matching substrate of the matching layer, the mainboard dielectric board of the mainboard and the balun dielectric board of the balun are all made of non-metallic materials.

[0062] The above-mentioned cavity-backed butterfly antenna is designed with a cavity-backed structure for improving the forward gain of the antenna (wherein the supporting layer is used to support the matching layer, and the matching layer is used to change the phase of the backward radiated wave when it reaches the antenna radiating surface and reduce the cross-sectional height) and a butterfly structure with ultra-wideband radiation characteristics (wherein the main board is used to constitute the radiating body of the butterfly antenna, and the balun is used to achieve impedance matching and balanced and unbalanced conversion), so that the cavity-backed butterfly antenna has both high gain and ultra-wideband performance characteristics, ensures the effectiveness of signal transmission and reception, and reduces the volume and mass, achieves miniaturization, and improves portability; the cavity-backed structure and the butterfly structure are spaced apart to improve the forward gain, low-frequency gain and low-frequency bandwidth, achieve a low profile, and ensure good directivity; the matching substrate and the bottom plate are spaced apart to optimize the S11 parameters and reduce the metal cavity-backed structure. Increased current reflection; there is a gap between the balun and the edge of the matching port to reduce the mutual coupling effect between the balun and the back cavity structure to ensure radiation uniformity; the matching substrate is a plate-like structure and has the same length and width as the bottom plate to make the back reflection radiate uniformly to ensure the consistency of the influence of the back radiation electromagnetic wave; the balun is vertically arranged in the middle of the mainboard, and two symmetrical circular radiation patches are arranged on the bottom surface of the mainboard dielectric board as antenna arms, and a plurality of inclined strip gaps and loading resistors are designed on the antenna arms to achieve ultra-wideband, and to achieve compactness and miniaturization; the operating frequency of the antenna in this embodiment is 0.32~0.98GHz, which can achieve high gain, ultra-wideband and miniaturization performance characteristics, can be widely used in scenes such as ground penetrating radar, and is of great significance for achieving high resolution and high precision ground penetrating radar.

[0063] Preferably, among the four side panels, the heights of two opposite side panels are the same, and the heights of two adjacent side panels are different, so as to reduce the influence on the S11 parameter, reduce port reflection, and further expand the forward gain of the antenna.

[0064] Further preferably, the bottom plate is a rectangular structure, the height of the two side plates connected to the long side of the bottom plate is less than the height of the other two side plates, and the two side plates connected to the short side of the bottom plate are flush with the top surface of the main board, so as to greatly improve the low-frequency gain, greatly expand the low-frequency bandwidth, and reduce the performance impact in the magnetic field direction. Figure 7 and Figure 8 shown.

[0065] In one embodiment, a plurality of strip-shaped slots are provided on the radiation patch of the butterfly structure. The plurality of strip-shaped slots are symmetrically spaced on both sides of the symmetry axis in the length direction of the bottom of the mainboard dielectric plate; one end of the strip-shaped slot is provided at the edge of the radiation patch facing the corner of the mainboard dielectric plate, and the other end extends toward the bottom center of the mainboard dielectric plate, so that the strip-shaped slot is not vertically arranged with the symmetry axis in the length direction of the bottom of the mainboard dielectric plate; the distance between the other end of all the strip-shaped slots and the symmetry axis in the length direction of the bottom of the mainboard dielectric plate is equal. That is to say, the strip-shaped slots on the same side of the same radiation patch are grouped as one group, and the four groups of radiation patches point from the four corners of the mainboard dielectric plate to the center direction of the mainboard dielectric plate respectively, and the minimum distance between the two groups of strip-shaped slots on the same radiation patch is equal. The above arrangement can improve the current distribution, extend the effective current path, achieve ultra-wideband, and realize the compactness and miniaturization of the antenna.

[0066] Preferably, on the same radiation patch, the strip slots on the same side are arranged in parallel with equal spacing, and the distance between adjacent strip slots is 6 to 7 times the width of the strip slot, so as to further optimize the S11 parameter and achieve better matching performance within a wide band.

[0067] Further preferably, in the same radiation patch, the length of the strip gap on the same side gradually decreases in the direction away from the center of the mainboard dielectric board, so as to further optimize the S11 parameter, achieve better matching performance within the broadband, and achieve miniaturization while ensuring performance.

[0068] More preferably, a loading resistor is provided on the edge of the radiation patch at the position corresponding to the other end of each strip-shaped gap, and there is a gap between adjacent loading resistors, and the width of the gap is not equal to the width of the strip-shaped gap, so as to eliminate the reflection generated in the closed structure, and further achieve ultra-wideband and miniaturization. Specifically, the loading resistor uses a chip resistor, which is soldered to the end of the strip-shaped gap (specifically, the end of the strip-shaped gap at the edge of the radiation patch) with solder, and the resistance value of the loading resistor is equal to 140Ω. In actual processing, appropriate copper foil can be added at one end of the strip-shaped gap to adapt to the size specifications of different types of resistors.

[0069] In one embodiment, the two conductors of the butterfly structure are both exponential transmission lines, and the two metal conductors have the same gradual change trend along the same direction, that is, along the length direction of the balun, the widths of the two metal conductors gradually decrease or increase; the two conductors do not overlap, and are both axially symmetrically distributed about the symmetry axis in the length direction of the balun dielectric plate.

[0070] Preferably, the widths of the corresponding connection ends on the two metal wires are equal, and the widths of the corresponding signal ends on the two metal wires are unequal.

[0071] Further preferably, the signal end of the balun is used for SMA signal input, and an SMA connector is used for feeding. For example, the signal end is connected to an SMA straight plug, and the connection end of the balun is connected to an antenna feeding port. For example, a 50Ω straight plug-in SMA connector is used for feeding.

[0072] In a specific embodiment, the antenna is an ultra-wideband cavity-backed butterfly antenna. The bottom plate size is 350mm×200mm×1mm, the two side plates are 350mm×30mm×1mm, and the other two side plates are 200mm×95mm×1mm; the material of the matching substrate is Rogers R04350B with a dielectric constant of 3.48, the size is 350mm×200mm×0.724mm, the material of the matching unit is immersion gold, the size is 24.5mm×24.5mm, the thickness is 1oz, and the distance between adjacent matching units is 1mm; the distance between the matching substrate and the bottom plate is 20mm, the size of the matching port is 50mm×50mm; the distance between the main board and the matching layer is 70mm. The material of the mainboard dielectric board is FR-4, with a length of 300mm, a width of 150mm and a thickness of 2mm; the material of the radiation patch is copper foil, with a radius of 70mm, a thickness of 1oz, and a distance between two radiation patches of 2mm; each radiation patch is provided with 6*2 strip-shaped gaps, and the distance between the other end of the strip-shaped gap and the axis of symmetry in the length direction of the top of the mainboard dielectric board is 11mm, the width of the strip-shaped gap is 3mm, the distance between two adjacent strip-shaped gaps is 20mm, and the angle between the strip-shaped gap and the x-axis is 30°; the material of the balun dielectric board is FR-4, with a length of 100mm, a width of 30mm and a thickness of 2mm; the material of the wire is copper foil and a thickness of 1oz; the length of the balun slot is the width of the balun, i.e. 30mm, and the width is the thickness of the balun, i.e. 2mm, to ensure that the balun can be inserted into the mainboard, and the specific processing belongs to the existing technology.

[0073] The cavity-backed butterfly antenna in the above embodiment was simulated using electromagnetic simulation software CST, and physically tested using a vector network analyzer (VNA), and the results are as follows.

[0074] (1) Impedance characteristics:

[0075] like Fig. 9 As shown in the impedance characteristic simulation diagram, due to the increase in current length, the low-frequency cutoff frequency is lower, which can better adapt to the working frequency band requirements of the environment (for example: ground penetrating radar). The overall antenna after balun impedance matching can be well matched with the 50Ω straight-in SMA connector.

[0076] (2) Return loss |S11|:

[0077] like Fig.10The return loss simulation diagram shown is used to simulate and verify the working bandwidth of the antenna. The simulation results show that the bandwidth of the antenna (based on |S11|<-10dB) is 0.34~0.95GHz, and the relative bandwidth is 93%.

[0078] like Fig.11 As shown in the measured return loss diagram, the measured results show that the antenna has a relative bandwidth of 101% in the range of 0.32 to 0.98 GHz, and the measured results are consistent with the simulation results.

[0079] (3) Maximum gain:

[0080] like Fig.12 The +Z direction gain simulation diagram shown in FIG. Fig.13 As shown in the measured graph of the +Z direction gain, the gain of the antenna within the working bandwidth is greater than 2.5dBi, and at 0.9GHz, the antenna gain reaches its maximum value of 7dBi.

[0081] (4) Direction diagram:

[0082] like Fig.14 The E-plane radiation pattern of the antenna at 0.4 GHz and Fig.15 From the H-plane radiation pattern of the antenna at 0.4 GHz, it can be found that the antenna has good directional radiation characteristics and has good transmission and reception capabilities for electromagnetic waves in different directions.

[0083] This application designs a new back cavity structure to improve the forward gain and low-frequency bandwidth of the antenna. The impedance bandwidth of the antenna is 0.32-0.98 GHz, and the maximum gain is 7 dBi. Each strip slot has a loading resistor at the end to reduce current reflection. In addition, a microstrip balun is designed to achieve balanced feeding and impedance matching. The antenna has a novel design, a simple structure, and is easy to process, with a compact size (0.36λmax×0.21λmax×0.09λmax, where λmax is the wavelength length corresponding to the low-frequency cutoff frequency of the antenna).

[0084] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A cavity-backed butterfly antenna, characterized in that: include: Back cavity structure and butterfly structure; The back cavity structure comprises: a supporting layer and a matching layer connected to the supporting layer; the supporting layer comprises a bottom plate and four side plates connected to the bottom plate to form a box-shaped structure; the matching layer is spaced apart from the bottom plate and connected to one or more side plates; through holes are provided on the bottom plate and the matching layer to form a matching port; The butterfly structure includes: a main board and a balun connected to the main board; The butterfly structure is spaced apart from the back cavity structure, the main board is arranged at one side of the matching layer, and the balun is connected to the input end after passing through the matching port to form a back cavity type butterfly antenna.

2. The cavity-backed butterfly antenna according to claim 1, characterized in that: Among the four side panels, two opposite side panels have the same height, and two adjacent side panels have different heights.

3. A cavity-backed butterfly antenna according to claim 1 or 2, characterized in that: The bottom plate is a rectangular structure, the height of the two side plates connected to the long sides of the bottom plate is smaller than the height of the other two side plates, and the two side plates connected to the short sides of the bottom plate are flush with the top surface of the main plate.

4. A cavity-backed butterfly antenna according to claim 1 or 2, characterized in that: The matching layer includes: a matching substrate and a plurality of matching units arranged on the matching substrate; There are gaps between adjacent matching units, and a plurality of matching units are arranged in an array to form a rectangular matching array.

5. The cavity-backed butterfly antenna according to claim 4, characterized in that: The matching substrate has the same length and width as the bottom plate.

6. A cavity-backed butterfly antenna according to claim 1 or 2, characterized in that: The mainboard comprises: a mainboard dielectric board of a rectangular plate structure and two circular radiation patches symmetrically arranged on the bottom surface of the mainboard dielectric board; The balun comprises: a balun dielectric plate of a rectangular plate structure and two wires respectively arranged on two sides of the balun dielectric plate; along the length direction of the balun, one end is a signal end and the other end is a connection end; The connection end of the balun is vertically arranged at the bottom center of the mainboard, the symmetry axis of the connection end in the length direction is collinear with the symmetry axis of the bottom of the mainboard dielectric board in the width direction, and two conductors are respectively connected to a radiation patch to form an ultra-wideband antenna.

7. The cavity-backed butterfly antenna according to claim 6, characterized in that: The radiation patch is provided with a plurality of strip-shaped gaps; A plurality of strip-shaped gaps are symmetrically spaced on both sides of a symmetry axis in the length direction of the bottom of the mainboard dielectric board; one end of the strip-shaped gap is arranged at a position at the edge of the radiation patch toward the corner of the mainboard dielectric board, and the other end extends toward the bottom center of the mainboard dielectric board, so that the strip-shaped gap is not arranged perpendicularly to the symmetry axis in the length direction of the bottom of the mainboard dielectric board.

8. The cavity-backed butterfly antenna according to claim 7, characterized in that: On the same radiation patch, the strip-shaped slots on the same side are arranged in parallel at equal intervals, and the distance between adjacent strip-shaped slots is 6 to 7 times the width of the strip-shaped slots.

9. The cavity-backed butterfly antenna according to claim 8, characterized in that: In the same radiation patch, the length of the strip-shaped gap on the same side gradually decreases in a direction away from the center of the main board dielectric board.

10. The cavity-backed butterfly antenna according to claim 7, characterized in that: A loading resistor is arranged on the edge of the radiation patch at a position corresponding to the other end of each strip-shaped gap, and there is a gap between adjacent loading resistors.

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