A compact resonant cavity antenna with adjustable two-dimensional dimensions

Abstract

A compact resonant cavity antenna with adjustable two-dimensional size belongs to the field of antenna technology and solves the problem of how to achieve two-dimensional size reduction of a waveguide antenna without reducing the aperture efficiency of the antenna. The H-shaped cavity of the antenna of the present invention is connected to a first rectangular slot opened at the outer bottom of a coupling cavity. The coupling cavity and the resonant cavity are connected via a coupling slot. The resonant cavity and four polarization conversion cavities are connected via four radiation slots. Two groups of orthogonally arranged cross-shaped adjustment blocks are provided inside the coupling cavity, and two groups of horizontal adjustment blocks are provided inside the resonant cavity. The cross-shaped adjustment blocks and the horizontal adjustment blocks tune the coupling cavity and the resonant cavity to achieve two-dimensional size reduction. The polarization conversion cavity is used to convert linearly polarized signals into circularly polarized signals. The antenna has the advantages of small size, high radiation efficiency, and high power capacity. The antenna can be processed using a milling process, has high reliability, and low cost. The antenna has great application prospects in large-angle scanning phased array systems.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas and relates to a compact resonant cavity antenna with adjustable two-dimensional dimensions. Background Art

[0002] In recent years, planar slot antennas have garnered extensive attention and research due to their low profile, integration capabilities, and ease of array formation. Slot antennas are antennas with slots cut into waveguides, metal plates, coaxial cables, or resonant cavities, through which electromagnetic waves radiate into the external space. They are characterized by their light weight, well-planar structure, and conformability to the object on which they are mounted. The aperture amplitude distribution of slot array antennas is easily controlled, resulting in high aperture utilization and low or extremely low sidelobes. Slot antennas also offer advantages such as a robust structure, compact size, ease of fabrication, convenient power feeding, and simple installation. Common slot antennas are divided into microstrip slot antennas and waveguide slot antennas. Microstrip slot antennas have been extensively researched due to their conformability, ease of fabrication, and low cost, but they suffer from high losses, low power handling, and low efficiency. Waveguide slot array antennas, on the other hand, are widely used due to their outstanding advantages, including low losses, high power handling, high radiation efficiency, and stable performance.

[0003] When microwave signals are transmitted through a waveguide, an induced current is generated on the inner surface of the metal waveguide. A waveguide slot is created in the waveguide wall. When the slot cuts off the current flowing through the waveguide wall, current flows to the outer wall, simultaneously stimulating an electric field across the slot. This electric field is equivalent to a surface current distribution along the slot axis. The current flowing through the outer wall and the magnetic current flowing through the slot radiate electromagnetic waves into space. Typically, the width of a single waveguide array antenna needs to be greater than half the operating wavelength to avoid electromagnetic wave transmission cutoff. The length of a single waveguide array antenna is typically an integer multiple of half the waveguide wavelength, with one radiating slot corresponding to each half-waveguide wavelength, thereby improving the antenna's aperture utilization. Arranging single waveguide array antennas in parallel along their narrow edges creates a two-dimensional waveguide array antenna.

[0004] According to the characteristics of waveguide transmission, under the premise that the size of the radiation slot remains unchanged, when the waveguide width increases, the waveguide wavelength will decrease, and the corresponding waveguide length will also need to be shortened; and when the waveguide width decreases, the waveguide wavelength will increase, and the corresponding waveguide length will also need to be increased. Due to the above-mentioned constraints on the size of the waveguide antenna in two dimensions, it is difficult for waveguide antennas to achieve size reduction in two dimensions at the same time, which significantly restricts the application scenarios of waveguide antennas. Existing technologies often mechanically compress the size of the waveguide antenna along the slot extension direction by reducing the number of slots, shortening the slot spacing, etc. In this case, each slot no longer has a one-to-one correspondence with each half waveguide wavelength, which will significantly reduce the aperture efficiency of the antenna. Summary of the Invention

[0005] The technical solution of the present invention is used to solve the problem of how to achieve two-dimensional size reduction of a waveguide antenna without reducing the antenna aperture efficiency.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] A compact resonant cavity antenna with adjustable two-dimensional dimensions comprises: a feeding layer structure (10), a coupling layer structure (20), a resonant layer structure (30), and a polarization conversion layer structure (40), wherein the feeding layer structure (10) is embedded below the coupling layer structure (20), the coupling layer structure (20) is embedded below the resonant layer structure (30), and the polarization conversion layer structure (40) is stacked above the resonant layer structure (30); the H-shaped cavity (102) of the feeding layer structure (10) is connected to a first rectangular groove (206) opened at the outer bottom of the coupling cavity (201) of the coupling layer structure (20), the coupling cavity (201) of the coupling layer structure (20) is connected to the resonant cavity (301) of the resonant layer structure (30) through two coupling slits (202) of the coupling layer structure (20), and the resonant layer structure (30) is connected to the H-shaped cavity (102) of the feeding layer structure (10). The resonant cavity (301) of the (30) and the four polarization conversion cavities (401) of the polarization conversion layer structure (40) are connected through the four radiation slots (302) of the resonant layer structure (30); two groups of orthogonally arranged cross-shaped adjustment blocks (205) are arranged inside the coupling cavity (201) of the coupling layer structure (20); two groups of horizontal adjustment blocks (304) are arranged inside the resonant cavity (301) of the resonant layer structure (30); two-dimensional size reduction is achieved through the tuning effect of the cross-shaped adjustment blocks (205) and the horizontal adjustment blocks (304) on the coupling cavity (201) and the resonant cavity (301); in the polarization conversion layer structure (40), the polarization conversion cavity (401) composed of the first polarization conversion plate (4012) and the second polarization conversion plate (4013) is used to convert a linear polarization signal into a circular polarization signal.

[0008] Furthermore, the feed layer structure (10) is formed by machining an H-shaped cavity (102) in a rectangular parallelepiped feed waveguide (101), and the feed layer structure (10) is penetrated by upper and lower openings.

[0009] Furthermore, the coupling layer structure (20) has two coupling slits (202) provided at the top middle position of the coupling cavity (201) along the long side direction, a rectangular parallelepiped tuning diaphragm (203) provided at the top middle position inside the coupling cavity (201) along the short side direction, two coupling tuning metal blocks (204) provided below the top of the coupling cavity (201), the two coupling tuning metal blocks (204) extending downward from the top of the coupling cavity (201), the two coupling tuning metal blocks (204) distributed on the same side of the two coupling slits (202), and two orthogonally arranged cross-shaped adjustment blocks (205) symmetrically provided above the bottom of the coupling cavity (201).

[0010] Furthermore, the top of the resonant cavity (301) of the resonant layer structure (30) is provided with four radiation slots (302), the four radiation slots (302) form a 2×2 array and are parallel to the rectangular edge of the top of the resonant cavity (301), four radiation tuning metal blocks (303) are provided below the inner top of the resonant cavity (301), the four radiation tuning metal blocks (303) extend downward from the inner top of the resonant cavity (301), and the four radiation tuning metal blocks (303) are staggered and distributed on both sides of the four radiation slots (302), two horizontal adjustment blocks (304) are symmetrically provided above the inner bottom of the resonant cavity (301), the two horizontal adjustment blocks (304) are both parallel to the rectangular edge of the bottom of the resonant cavity (301), and a second rectangular groove (305) is provided on the outer bottom of the resonant cavity (301) along a direction parallel to the horizontal adjustment blocks (304), and the second rectangular groove (305) is used to embed the coupling cavity (201).

[0011] Furthermore, the polarization conversion layer structure (40) comprises four polarization conversion cavities (401), and the four polarization conversion cavities (401) are tightly combined to form a 2×2 array.

[0012] Furthermore, the polarization conversion cavity (401) includes: a polarization conversion cavity shell (4011), two first polarization conversion plates (4012), and two second polarization conversion plates (4013), wherein the polarization conversion cavity shell (4011) is a rectangular metal frame with upper and lower openings, and the two first polarization conversion plates (4012) and the two second polarization conversion plates (4013) are respectively vertically arranged on four inner surfaces inside the rectangular metal frame, wherein the two first polarization conversion plates (4012) are centrally symmetrically distributed about the center of the rectangular metal frame, and the two second polarization conversion plates (4013) are centrally symmetrically distributed about the center of the rectangular metal frame.

[0013] Furthermore, the coupling slit (202) is one of a straight slit, an elliptical slit or an H-shaped slit.

[0014] Furthermore, the coupling tuning metal block (204) is in the shape of a cuboid, a cylinder or a triangular prism.

[0015] Furthermore, the radiation slit (302) is one of a straight slit, an elliptical slit or an H-shaped slit.

[0016] Furthermore, the radiation tuning metal block (303) is in the shape of a cuboid, a cylinder or a triangular prism.

[0017] The advantages of the present invention are:

[0018] The H-shaped cavity of the antenna of the present invention is connected to a first rectangular slot on the outer bottom of the coupling cavity. The coupling cavity and the resonant cavity are connected via a coupling slot. The resonant cavity and the four polarization conversion cavities are connected via four radiation slots. Two groups of orthogonally arranged cross-shaped adjustment blocks are provided inside the coupling cavity, and two groups of horizontal adjustment blocks are provided inside the resonant cavity. The cross-shaped adjustment blocks and the horizontal adjustment blocks are used to tune the coupling cavity and the resonant cavity, thereby achieving two-dimensional size reduction. The polarization conversion cavity is used to convert linearly polarized signals into circularly polarized signals. The antenna of the present invention has the advantages of small size, high radiation efficiency, and high power capacity.

[0019] The antenna of the present invention can be manufactured using a milling process, which is a mature process with high reliability, wide application range and low cost. Based on the milling process, a large-scale antenna array based on the antenna unit can be processed in an integrated manner, rather than processing the units independently and then splicing them together. This method can ensure processing accuracy and reduce processing costs.

[0020] The antenna of the present invention has good circular polarization impedance matching and radiation characteristics within the operating frequency band. At the same time, since the premise of high-performance large-angle scanning of the phased array system is small unit spacing, the antenna of the present invention has great application prospects in large-angle scanning phased array systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A three-dimensional exploded front view of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0022] Figure 2 A front perspective view of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0023] Figure 3 A side perspective view of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0024] Figure 4 A front perspective view of a feed layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0025] Figure 5 A top view of the feeding layer structure of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0026] Figure 6 A front perspective view of a coupling layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0027] Figure 7 A top perspective view of a coupling layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0028] Figure 8 A front perspective view of a coupling layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0029] Figure 9 A side perspective view of a coupling layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0030] Figure 10 A front perspective view of a resonant layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0031] Figure 11 A top perspective view of a resonant layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0032] Figure 12 A front perspective view of a resonant layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0033] Figure 13 A side perspective view of a resonant layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0034] Figure 14 A front perspective view of a polarization conversion layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0035] Figure 15 A top view of a polarization conversion layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0036] Figure 16 A front perspective view of a polarization conversion cavity of a polarization conversion layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0037] Figure 17 A front perspective view of a first polarization conversion plate of a polarization conversion layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0038] Figure 18 A front perspective view of a second polarization conversion plate of a polarization conversion layer structure of a compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0039] Figure 19 Schematic diagram of electric field distribution in waveguides of the same length but different widths;

[0040] Figure 20 Schematic diagram of the electric field distribution in the resonant cavity of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0041] Figure 21 The impedance matching characteristic curve of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0042] Figure 22 1. The axial ratio characteristic curve of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention;

[0043] Figure 23 This is the radiation pattern of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] The technical solution of the present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0046] Example 1

[0047] like Figures 1 to 3 As shown, the two-dimensionally adjustable compact resonant cavity antenna of an embodiment of the present invention includes a four-layer structure, all of which adopt an all-metal structure, namely a feeding layer structure 10, a coupling layer structure 20, a resonant layer structure 30, and a polarization conversion layer structure 40, wherein the feeding layer structure 10 is embedded below the coupling layer structure 20, the coupling layer structure 20 is embedded below the resonant layer structure 30, and the polarization conversion layer structure 40 is stacked above the resonant layer structure 30.

[0048] like Figure 4 and Figure 5As shown, the feeding layer structure 10 is formed by machining an H-shaped cavity 102 in a rectangular feeding waveguide 101. The feeding layer structure 10 is penetrated by upper and lower openings. When the antenna is transmitting, the electromagnetic signal rectangle is input from the lower opening of the feeding waveguide 101 and output from the upper opening of the rectangular feeding waveguide 101 to the coupling cavity 201 of the coupling layer structure 20.

[0049] like Figures 6 to 9 As shown, the coupling layer structure 20 has two coupling slits 202 provided at the top center of the coupling cavity 201 along the long side direction, a rectangular tuning diaphragm 203 provided at the top center of the interior of the coupling cavity 201 along the short side direction, two coupling tuning metal blocks 204 provided below the top of the interior of the coupling cavity 201, extending downward from the top of the interior of the coupling cavity 201, and distributed on the same side of the two coupling slits 202, two orthogonally arranged cross-shaped adjustment blocks 205 symmetrically provided above the interior bottom of the coupling cavity 201, and a first rectangular groove 206 provided at the outer bottom of the coupling cavity 201 along the short side direction, for embedding the rectangular feeding waveguide 101.

[0050] like Figures 10 to 13 As shown, four radiation slots 302 are provided at the top of the resonant cavity 301 of the resonant layer structure 30. The four radiation slots 302 form a 2×2 array and are parallel to the edges of the top rectangle of the resonant cavity 301. Four radiation tuning metal blocks 303 are provided below the inner top of the resonant cavity 301. The four radiation tuning metal blocks 303 extend downward from the inner top of the resonant cavity 301. The four radiation tuning metal blocks 303 are staggered on both sides of the four radiation slots 302. Two horizontal adjustment blocks 304 are symmetrically provided above the inner bottom of the resonant cavity 301. Both horizontal adjustment blocks 304 are parallel to the edges of the bottom rectangle of the resonant cavity 301. A second rectangular groove 305 is provided at the outer bottom of the resonant cavity 301 in a direction parallel to the horizontal adjustment blocks 304. The second rectangular groove 305 is used to embed the coupling cavity 201.

[0051] The coupling slot 202 is one of a straight slot, an elliptical slot or an H-shaped slot, and the radiation slot 302 is one of a straight slot, an elliptical slot or an H-shaped slot.

[0052] The coupling tuning metal block 204 is a rectangular parallelepiped, a cylindrical shape, or a triangular prism, and the radiation tuning metal block 303 is a rectangular parallelepiped, a cylindrical shape, or a triangular prism.

[0053] In order to reduce the size of the antenna in two dimensions, two groups of orthogonally arranged cross-shaped adjustment blocks 205 are designed inside the coupling cavity 201 of the coupling layer structure 20; at the same time, two groups of horizontal adjustment blocks 304 are also designed inside the resonant cavity 301 of the resonant layer structure 30.

[0054] like Figure 14 and Figure 15 As shown, the polarization conversion layer structure 40 includes four polarization conversion cavities 401 , and the four polarization conversion cavities 401 are tightly combined to form a 2×2 array.

[0055] like Figure 16 As shown, the polarization conversion cavity 401 includes: a polarization conversion cavity shell 4011, two first polarization conversion plates 4012, and two second polarization conversion plates 4013. The polarization conversion cavity shell 4011 is a rectangular metal frame with upper and lower openings. The two first polarization conversion plates 4012 and the two second polarization conversion plates 4013 are vertically arranged on the four inner surfaces inside the rectangular metal frame, respectively. The two first polarization conversion plates 4012 are centrally symmetrically distributed about the center of the rectangular metal frame, and the two second polarization conversion plates 4013 are centrally symmetrically distributed about the center of the rectangular metal frame. The polarization conversion cavity 401 is used to convert linear polarization signals into circular polarization signals.

[0056] like Figures 17 and 18 As shown, the first polarization conversion plate 4012 and the second polarization conversion plate 4013 are trapezoidal structures, and the hypotenuse of the trapezoidal structure adopts a stepped structure, which is beneficial to improving the bandwidth characteristics of the antenna; by adjusting the relative positions of the first polarization conversion plate 4012 and the second polarization conversion plate 4013, the polarization conversion cavity 401 can achieve left-hand circular polarization or right-hand circular polarization.

[0057] The working mechanism of the polarization conversion cavity 401 is as follows: any electromagnetic wave can be decomposed into two orthogonal modes. The first polarization conversion plate 4012 and the second polarization conversion plate 4013 are used to modulate one mode respectively. When the thickness of the two polarization conversion plates is different, the amplitude and phase modulation of the corresponding modes have different effects. When the two modes are modulated to have equal amplitude and a phase difference of 90°, the two modes can be synthesized into circular polarization.

[0058] The operating principle of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to an embodiment of the present invention is as follows:

[0059] The H-shaped cavity 102 of the feeding layer structure 10 is connected to the first rectangular groove 206 opened at the outer bottom of the coupling cavity 201 of the coupling layer structure 20. The coupling cavity 201 of the coupling layer structure 20 is connected to the resonant cavity 301 of the resonant layer structure 30 through the two coupling slits 202 of the coupling layer structure 20. The two coupling tuning metal blocks 204 on one side of the two coupling slits 202 are used to adjust the electromagnetic coupling characteristics. The rectangular tuning diaphragm 203 between the two coupling slits 202 can also be used to adjust the electromagnetic coupling characteristics. Magnetic coupling characteristics; the resonant cavity 301 of the resonant layer structure 30 and the four polarization conversion cavities 401 of the polarization conversion layer structure 40 are connected through the four radiation slots 302 of the resonant layer structure 30, and the four radiation tuning metal blocks 303 staggeredly distributed below the two sides of the four radiation slots 302 are used to adjust the electromagnetic radiation characteristics; in the polarization conversion layer structure 40, the polarization conversion cavity 401 composed of the first polarization conversion plate 4012 and the second polarization conversion plate 4013 is used to convert the linear polarization signal into a circular polarization signal.

[0060] When the antenna is transmitting, the electromagnetic signal is input through the lower opening of the rectangular feed waveguide 101, output from the upper opening of the rectangular feed waveguide 101 to the coupling cavity 201 of the coupling layer structure 20, then coupled into the resonant cavity 301 of the resonant layer structure 30 through the two coupling slits 202 of the coupling layer structure 20, and then enters the four polarization conversion cavities 401 of the polarization conversion layer structure 40 through the four radiation slits 302 of the resonant layer structure 30, where it is synthesized into circular polarization and ultimately radiated into space. When the antenna is receiving, the electromagnetic signal process is the opposite of that during transmission.

[0061] Simulation test verification

[0062] To further verify the technological advancement of the present invention's compact, two-dimensionally adjustable resonant cavity antenna, the inventors conducted relevant theoretical calculations. According to electromagnetic theory, for a waveguide antenna, assuming the size of the radiation slot remains unchanged (i.e., the number of standing waves remains the same), increasing the waveguide width decreases the waveguide length; conversely, decreasing the waveguide width increases the waveguide length. Figure 19 Schematic diagram of the electric field distribution in waveguides of the same length but different widths, as shown in Figure 19 As shown in FIG, the relevant electromagnetic simulation results further confirm that the waveguide antenna has the above-mentioned constraints on its two-dimensional dimensions, which makes it difficult to realize a two-dimensional small-sized waveguide antenna unit.

[0063] like Figure 20 FIG. 1 is a schematic diagram of the electric field distribution in the resonant cavity 301 of the compact resonant cavity antenna with adjustable two-dimensional dimensions according to the present invention. Figure 20As can be seen, both dimensions of resonant cavity 301 are close to one operating wavelength, forming a 2×2 standing wave array. Resonant cavity 301 can be viewed as two waveguides, each approximately half the operating wavelength wide, placed side by side. For a conventional waveguide resonant cavity to form a 2×2 standing wave array, if one dimension approaches one operating wavelength, electromagnetic theory suggests the other dimension must be significantly larger than one operating wavelength. The significant reduction in two dimensions of resonant cavity 301 of the present invention is due to the tuning effect of the cross-shaped adjustment block 205 and the horizontal adjustment block 304 on the coupling cavity 201 and resonant cavity 301.

[0064] Figures 21 to 23 The impedance matching characteristic curve, axial ratio characteristic curve and radiation pattern of the two-dimensional size adjustable compact resonant cavity antenna of the present invention are given in sequence. Figures 21 to 23 It can be seen that the compact resonant cavity antenna with adjustable two-dimensional size of the present invention has good impedance matching and circular polarization radiation performance within the working frequency band.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A compact resonant cavity antenna with adjustable two-dimensional dimensions, characterized in that: include: A feeding layer structure (10), a coupling layer structure (20), a resonant layer structure (30), and a polarization conversion layer structure (40), wherein the feeding layer structure (10) is embedded below the coupling layer structure (20), the coupling layer structure (20) is embedded below the resonant layer structure (30), and the polarization conversion layer structure (40) is stacked above the resonant layer structure (30); the H-shaped cavity (102) of the feeding layer structure (10) is connected to a first rectangular groove (206) opened at the outer bottom of the coupling cavity (201) of the coupling layer structure (20), the coupling cavity (201) of the coupling layer structure (20) is connected to the resonant cavity (301) of the resonant layer structure (30) through two coupling slits (202) of the coupling layer structure (20), and the resonant cavity (301) of the resonant layer structure (30) is connected to the H-shaped cavity (102) of the feeding layer structure (10). 1) is connected to four polarization conversion cavities (401) of a polarization conversion layer structure (40) through four radiation slots (302) of a resonance layer structure (30); two groups of orthogonally arranged cross-shaped adjustment blocks (205) are arranged inside the coupling cavity (201) of the coupling layer structure (20); two groups of horizontal adjustment blocks (304) are arranged inside the resonance cavity (301) of the resonance layer structure (30); two-dimensional size reduction is achieved through the tuning effect of the cross-shaped adjustment blocks (205) and the horizontal adjustment blocks (304) on the coupling cavity (201) and the resonance cavity (301); in the polarization conversion layer structure (40), a polarization conversion cavity (401) composed of a first polarization conversion plate (4012) and a second polarization conversion plate (4013) is used to convert a linear polarization signal into a circular polarization signal.

2. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 1, characterized in that: The feed layer structure (10) is formed by machining an H-shaped cavity (102) in a rectangular parallelepiped feed waveguide (101), and the feed layer structure (10) is penetrated by upper and lower openings.

3. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 1, wherein: Two coupling slits (202) are provided at the top middle position of the coupling cavity (201) of the coupling layer structure (20) along the long side direction; a rectangular parallelepiped tuning diaphragm (203) is provided at the top middle position inside the coupling cavity (201) along the short side direction; two coupling tuning metal blocks (204) are provided below the top of the coupling cavity (201); the two coupling tuning metal blocks (204) extend downward from the top of the coupling cavity (201); the two coupling tuning metal blocks (204) are distributed on the same side of the two coupling slits (202); and two orthogonally arranged cross-shaped adjustment blocks (205) are symmetrically provided above the bottom of the coupling cavity (201).

4. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 1, wherein: The resonant cavity (301) of the resonant layer structure (30) is provided with four radiation slots (302) at the top, the four radiation slots (302) form a 2×2 array and are parallel to the rectangular edges of the top of the resonant cavity (301); four radiation tuning metal blocks (303) are provided below the inner top of the resonant cavity (301); the four radiation tuning metal blocks (303) extend downward from the inner top of the resonant cavity (301); the four radiation tuning metal blocks (303) are staggered and distributed on both sides of the four radiation slots (302); two horizontal adjustment blocks (304) are symmetrically provided above the inner bottom of the resonant cavity (301); the two horizontal adjustment blocks (304) are both parallel to the rectangular edges of the bottom of the resonant cavity (301); a second rectangular groove (305) is provided on the outer bottom of the resonant cavity (301) along a direction parallel to the horizontal adjustment blocks (304); the second rectangular groove (305) is used to embed the coupling cavity (201).

5. The two-dimensionally adjustable compact resonant cavity antenna according to claim 1, characterized in that: The polarization conversion layer structure (40) comprises four polarization conversion cavities (401), and the four polarization conversion cavities (401) are tightly combined to form a 2×2 array.

6. The two-dimensionally adjustable compact resonant cavity antenna according to claim 5, characterized in that: The polarization conversion cavity (401) comprises: a polarization conversion cavity shell (4011), two first polarization conversion plates (4012), and two second polarization conversion plates (4013). The polarization conversion cavity shell (4011) is a rectangular metal frame with upper and lower openings. The two first polarization conversion plates (4012) and the two second polarization conversion plates (4013) are respectively vertically arranged on four inner surfaces inside the rectangular metal frame, wherein the two first polarization conversion plates (4012) are centrally symmetrically distributed about the center of the rectangular metal frame, and the two second polarization conversion plates (4013) are centrally symmetrically distributed about the center of the rectangular metal frame.

7. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 3, characterized in that: The coupling slit (202) is one of a straight slit, an elliptical slit or an H-shaped slit.

8. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 3, wherein: The coupling tuning metal block (204) is in the shape of a cuboid, a cylinder or a triangular prism.

9. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 4, characterized in that: The radiation slit (302) is one of a straight slit, an elliptical slit or an H-shaped slit.

10. The compact resonant cavity antenna with adjustable two-dimensional dimensions according to claim 4, characterized in that: The radiation tuning metal block (303) is in the shape of a cuboid, a cylinder or a triangular prism.

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