Functional Composite Two-Dimensional Metal Cavity Slot Array Antenna and its Array

Abstract

This invention provides a functional composite two-dimensional metal cavity slot array antenna, belonging to the antenna field. It includes a feed cavity, a first cover plate at the top of the feed cavity, a radiating cavity above the first cover plate, and a polarization conversion structure. The feed cavity contains multiple sets of periodic intermediate-frequency anti-interference metal blocks and high-frequency anti-interference metal blocks. A coupling slot on the first cover plate connects to the radiating cavity. A radiating slot is formed at the top of the radiating cavity. The polarization conversion structure is arranged in a stepped and open manner on both sides of the radiating slot, creating an undulating topography. An antenna array is also provided. The polarization conversion structure is arranged in a stepped and open manner on both sides of the radiating slot, creating an undulating topography. Electromagnetic signals are input to the feed cavity, enter the radiating cavity through the coupling slot, and then radiate linearly polarized electromagnetic waves outward through the radiating slot. After passing through the polarization conversion structure, the linearly polarized electromagnetic waves are decomposed into a set of orthogonal components with equal amplitude. There is a 90-degree phase difference between the two components, forming circular polarization radiation into space.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a functional composite two-dimensional metal cavity slot array antenna and its array. Background Technology

[0002] Metal cavity slot array antennas are a classic antenna type based on a metal cavity structure and slot radiating elements. These antennas achieve efficient signal transmission or reception by designing specific slot structures within the metal cavity and utilizing the cavity's resonant characteristics and the slots' radiation characteristics. Due to their advantages such as low loss and high polarization purity, they have gained widespread attention in military applications such as spaceborne and airborne communication and radar.

[0003] However, due to the continuous advancement of electronic technology, the current electromagnetic environment is extremely complex. Spaceborne or airborne applications must consider internal interference within their own equipment and also take effective measures to counter enemy electromagnetic interference. Therefore, improving the anti-interference capability of metal cavity slotted array antennas is essential.

[0004] Furthermore, antennas are mainly classified into two types based on their polarization: linear polarization and circular polarization. Linear polarization includes horizontal polarization, vertical polarization, and slant polarization, while circular polarization mainly includes left-hand circular polarization and right-hand circular polarization. A circularly polarized antenna is a special type of antenna whose transmitted or received electromagnetic waves have a rotating electric field vector direction. This characteristic gives circularly polarized antennas significant advantages in many applications. Especially in applications such as satellite-to-Earth communication or imaging, using circular polarization can effectively avoid the adverse effects of high path loss and polarization mismatch caused by the Faraday rotation effect when electromagnetic waves penetrate the ionosphere.

[0005] In summary, addressing the issues of interference suppression and circular polarization in metal cavity slot array antennas is a key aspect of this invention. Two-dimensional area arrays are the most widely used type of metal cavity slot array antenna in engineering applications, making technological improvements to them significant. In existing technologies, interference suppression in metal cavity slot array antennas is often achieved by cascading filters at the antenna's rear end, which significantly increases system complexity, hinders engineering implementation, and introduces substantial system losses. Furthermore, existing technologies for achieving circular polarization in metal cavity slot array antennas often employ the addition of polarization conversion devices, which are typically cumbersome to manufacture and costly. Summary of the Invention

[0006] The technical problem to be solved by this invention is: how to solve the problems of complex structure of existing metal cavity slot array antennas and the cumbersome processing and high manufacturing cost of using polarization conversion devices to achieve circular polarization.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: a functional composite two-dimensional metal cavity slot array antenna, including a feeding cavity, a first cover plate located on top of the feeding cavity, a radiating cavity located above the first cover plate, and a polarization conversion structure. The feeding cavity is provided with multiple sets of periodic intermediate frequency anti-interference metal blocks and high frequency anti-interference metal blocks. The coupling slot on the first cover plate is connected to the radiating cavity. A radiating slot is opened on the top of the radiating cavity. The polarization conversion structure is arranged in a stepped and open manner on both sides of the radiating slot to form a high and low undulating shape.

[0008] Beneficial Effects: This invention endows the antenna with anti-interference capabilities across multiple frequency bands by embedding a simple anti-interference periodic structure within the feed cavity. Compared to the traditional method of cascading filters at the antenna end, this invention effectively avoids cascading losses and reduces system size to some extent. The polarization conversion structure is arranged in a stepped and open manner on both sides of the radiation slot, forming an undulating topography. The electromagnetic signal is input into the feed cavity, enters the radiation cavity through the coupling slot, and then radiates linearly polarized electromagnetic waves outward through the radiation slot. After passing through the polarization conversion structure, the linearly polarized electromagnetic waves are decomposed into a set of orthogonal components with equal amplitude and a 90-degree phase difference between the two components, thus forming circular polarization and radiating into space. The polarization conversion structure is simple in structure, easy to manufacture, and has excellent performance. In addition, the antenna array exhibits a rough topography with undulating topography. According to the theory of diffuse reflection of electromagnetic waves, when electromagnetic waves irradiate a rough surface, the incident electromagnetic waves can produce a phase difference at the interface, and the scattered energy can be distributed in multiple angles, resulting in diffuse reflection and weakened reflection, thereby effectively improving the antenna's scattering characteristics.

[0009] Preferably, when the antenna is transmitting, the electromagnetic signal is fed into the feed cavity, enters the radiation cavity through the coupling slot, and then radiates linearly polarized electromagnetic waves outward through the radiation slot. After passing through the polarization conversion structure, the linearly polarized electromagnetic waves are decomposed into a set of orthogonal components with equal amplitudes and a 90-degree phase difference between the two components, forming circular polarization and radiating into space. When the antenna is receiving, the process is exactly the opposite of the transmitting process.

[0010] Preferably, the front end of the feeding cavity is configured as a feeding port protruding from the feeding cavity body, the rear end of the feeding cavity is closed, four coupling seams are equally spaced along the long side central axis of the first cover plate, and four feeding tuning metal blocks are equally spaced along the bottom long side central axis of the first cover plate, with the feeding tuning metal blocks distributed on one side of the coupling seams.

[0011] Preferably, the 32 intermediate frequency anti-interference metal blocks are divided into 8 groups, with 4 intermediate frequency anti-interference metal blocks in each group being equally spaced on the intermediate frequency metal pad along the width direction of the first cover plate. The 128 high frequency anti-interference metal blocks are divided into 8 groups, with 16 high frequency anti-interference metal blocks in each group forming a 2×8 array arranged on the high frequency metal pad. The intermediate frequency anti-interference metal blocks in each group and the high frequency anti-interference metal blocks in each group are alternately arranged along the length direction of the first cover plate. The upper surface of the intermediate frequency anti-interference metal blocks is flush with the upper surface of the high frequency anti-interference metal blocks, and the upper surface of the intermediate frequency anti-interference metal blocks is flush with the lower edge of the feed port.

[0012] Beneficial effects: The mid-frequency and high-frequency anti-interference metal blocks can be considered ideal magnetic conductors, significantly suppressing the propagation of electromagnetic waves in their respective frequency bands while having no effect on electromagnetic waves in other frequency bands. Therefore, the antenna possesses mid-frequency and high-frequency anti-interference capabilities. Furthermore, because the feed cavity uses a metallic waveguide structure, and waveguides have inherent cutoff frequency properties, electromagnetic waves below the corresponding frequency cannot propagate within it; therefore, the antenna also possesses low-frequency anti-interference capabilities.

[0013] Preferably, the radiation cavity includes a metal frame and a second cover plate located on top of the metal frame. The bottom of the metal frame is close to the upper surface of the first cover plate. Sixteen radiation slots are arranged in a 4×4 array on the second cover plate. Along the width direction of the feed cavity, multiple radiation tuning metal blocks are equally spaced at the bottom of the second cover plate. The radiation tuning metal blocks are staggered on both sides of the radiation slots.

[0014] Preferably, the polarization conversion structure includes 32 basic units, each basic unit including a first polarization conversion metal block, a second polarization conversion metal block, and a third polarization conversion metal block. The three metal blocks are all located on the top of the second cover plate and the end faces of the three metal blocks are closely attached to form a stepped shape.

[0015] Beneficial effects: The antenna structure of this invention features weak electromagnetic reflection, meaning it reduces the RCS (Radar Cross Section), making it highly promising for applications in electromagnetic stealth design. The polarization conversion structure is an open structure, which eliminates electromagnetic wave transmission cutoff issues and facilitates wider operating bandwidth. Furthermore, the open structure improves antenna heat dissipation, facilitates machining, reduces the vertical movement path of the machining tool, and lowers manufacturing costs.

[0016] Preferably, the first end face of the first polarization conversion metal block is closely attached to the second end face of the second polarization conversion metal block, the third end face of the second polarization conversion metal block is closely attached to the fourth end face of the third polarization conversion metal block, and the first side face of the first polarization conversion metal block is flush with the second side face of the second polarization conversion metal block and the third side face of the third polarization conversion metal block.

[0017] Beneficial effects: The close contact between the end faces of the three metal blocks increases the strength of the antenna structure and provides good protection against antenna deformation.

[0018] Preferably, the heights of the first polarization conversion metal block and the second polarization conversion metal block are equal, each being half a working wavelength, and the height of the third polarization conversion metal block is one-eighth of a working wavelength.

[0019] The present invention also provides a functional composite two-dimensional metal cavity slot array antenna array, which uses the aforementioned functional composite two-dimensional metal cavity slot array antenna as antenna unit, and arranges multiple antenna units in a planar array. The feed port 101 of each row of antenna units is located on the same side, and the rear ends of the feed cavities 102 of adjacent rows of antenna units are closely aligned. The upper surfaces of all antenna units are flush.

[0020] Beneficial effects: The antenna of this invention has a flat structure, which is extremely convenient for array applications. The antenna can be manufactured using milling technology, which is a mature process with high reliability, wide application range, and low cost.

[0021] The present invention also provides a functional composite two-dimensional metal cavity slot array antenna array, which uses the aforementioned functional composite two-dimensional metal cavity slot array antenna as antenna unit, and is coarsely arranged by multiple antenna units. The feed port 101 of each row of antenna units is located on the same side, and the rear ends of the feed cavity 102 of adjacent two rows of antenna units are closely attached and have a certain height difference. The upper surfaces of any two adjacent antenna units are not flush.

[0022] Beneficial effects: By setting the two-dimensional metal cavity slot array antenna array to have a rough undulating topography, the "roughness" of the large-scale array surface is further improved, thereby effectively improving the scattering characteristics of the antenna. Attached Figure Description

[0023] Figure 1 A perspective view of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0024] Figure 2 This is a front view of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0025] Figure 3 This is a top view of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0026] Figure 4 This is a side view of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0027] Figure 5This is a front view of the layered structure of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0028] Figure 6 This is a side view of the layered structure of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0029] Figure 7 This is a perspective view of the feed cavity and anti-interference structure of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0030] Figure 8 A perspective view of the feed cavity of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0031] Figure 9 This is a front view of the feed cavity of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0032] Figure 10 This is a top view of the feed cavity of the functional composite two-dimensional metallic cavity slot array antenna provided in Embodiment 1 of the present invention;

[0033] Figure 11 This is a side view of the feed cavity of the functional composite two-dimensional metallic cavity slot array antenna provided in Embodiment 1 of the present invention;

[0034] Figure 12 This is a three-dimensional view of the anti-interference structure in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0035] Figure 13 This is a front view of the anti-interference structure in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0036] Figure 14 This is a top view of the anti-interference structure in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0037] Figure 15 This is a side view of the anti-interference structure in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0038] Figure 16 A perspective view of the first cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0039] Figure 17 This is a front view of the first cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0040] Figure 18 This is a top view of the first cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0041] Figure 19 This is a side view of the first cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0042] Figure 20 This is a three-dimensional view of the metal frame in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0043] Figure 21 A perspective view of the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0044] Figure 22 This is a front view of the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0045] Figure 23 This is a top view of the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0046] Figure 24 This is a side view of the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0047] Figure 25 A perspective view of the polarization conversion structure and the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0048] Figure 26 This is a front view of the polarization conversion structure and the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0049] Figure 27 This is a top view of the polarization conversion structure and the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention.

[0050] Figure 28 This is a side view of the polarization conversion structure and the second cover plate in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention.

[0051] Figure 29 A three-dimensional view of the basic unit of the polarization conversion structure in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0052] Figure 30This is a front view of the basic unit of the polarization conversion structure in the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0053] Figure 31 This is a top view of the basic unit of the polarization conversion structure in the functional composite two-dimensional metallic cavity slot array antenna provided in Embodiment 1 of the present invention;

[0054] Figure 32 This is a side view of the basic unit of the polarization conversion structure in the functional composite two-dimensional metallic cavity slot array antenna provided in Embodiment 1 of the present invention.

[0055] Figure 33 The impedance matching performance curve of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0056] Figure 34 The circular polarization performance curve of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0057] Figure 35 The scattering performance curve of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 1 of the present invention;

[0058] Figure 36 This is a 2×4 scale antenna array of a functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 2 of the present invention;

[0059] Figure 37 This is a schematic diagram of the "planar array" of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 2 of the present invention;

[0060] Figure 38 This is a side view of the "planar array" of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 2 of the present invention;

[0061] Figure 39 This is a schematic diagram of the "rough array" of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 2 of the present invention;

[0062] Figure 40 This is a side view of the "rough array" of the functional composite two-dimensional metal cavity slot array antenna provided in Embodiment 2 of the present invention;

[0063] In the figure: 101 Feed port, 102 Feed cavity, 103 Intermediate frequency anti-interference metal block, 104 High frequency anti-interference metal block, 105 High frequency metal pad, 106 Intermediate frequency metal pad, 201 First cover plate, 202 Coupling seam, 203 Feed tuning metal block, 3 Metal frame, 401 Second cover plate, 402 Radiation seam, 403 Radiation tuning metal block, 5 Polarization conversion structure, 501 First polarization conversion metal block, 5011 First end face, 5012 First side face, 502 Second polarization conversion metal block, 5021 Second end face, 5022 Third end face, 5023 Second side face, 503 Third polarization conversion metal block, 5031 Fourth end face, 5032 Third side face. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0065] Example 1

[0066] like Figures 1 to 7 As shown, this embodiment provides a functional composite two-dimensional metal cavity slot array antenna, which adopts an all-metal structure and has high radiation efficiency and large power capacity. The antenna includes a feed cavity 102, a first cover plate 201 located on top of the feed cavity 102, a radiating cavity located above the first cover plate 201, and a polarization conversion structure 5. The feed cavity 102 is provided with multiple sets of periodic intermediate frequency anti-interference metal blocks 103 and high frequency anti-interference metal blocks 104. The coupling slot 202 on the first cover plate 201 is connected to the radiating cavity. A radiating slot 402 is opened on the top of the radiating cavity. The polarization conversion structure 5 is arranged in a stepped and open manner on both sides of the radiating slot 402 to form an undulating shape.

[0067] by Figure 1 In the diagram, the X direction represents the front-to-back direction of the antenna, the Y direction represents the left-to-right direction, and the Z direction represents the up-to-down direction. The feed cavity 102 and the first cover plate 201 form a metal waveguide structure. The feed cavity 102 is a rectangular slot, and the first cover plate 201 is a metal cover plate. The length direction of the rectangular slot is parallel to the X direction, the width direction is parallel to the Y direction, and the height direction is parallel to the Z direction. See also... Figures 8 to 11 The front end of the feed cavity 102 is configured as a feed port 101 protruding from the body of the feed cavity 102, and the rear end of the feed cavity 102 is closed. See [reference needed]. Figures 16 to 19Four coupling seams 202 are evenly spaced along the central axis of the long side of the first cover plate 201. The coupling seams 202 can be straight, elliptical, S-shaped, or H-shaped. Four power supply tuning metal blocks 203 are evenly spaced along the central axis of the bottom long side of the first cover plate 201, distributed on one side of the coupling seams 202. See also... Figure 18 The right edges of the four power-fed tuning metal blocks are respectively attached to the left edges of each coupling seam.

[0068] See Figures 12 to 15 The 32 intermediate frequency anti-interference metal blocks 103 are divided into 8 groups. The 4 intermediate frequency anti-interference metal blocks 103 in each group are equally spaced on the intermediate frequency metal pad 106 along the width direction (Y direction) of the first cover plate 201. The 128 high frequency anti-interference metal blocks 104 are divided into 8 groups. The 16 high frequency anti-interference metal blocks 104 in each group form a 2×8 array and are arranged on the high frequency metal pad 105. The intermediate frequency anti-interference metal blocks 103 and the high frequency anti-interference metal blocks 104 in each group are alternately arranged along the length direction (X direction) of the first cover plate 201. The sum of the heights of the high frequency anti-interference metal blocks 104 and the high frequency metal pad 105 is equal to the sum of the heights of the intermediate frequency anti-interference metal blocks 103 and the intermediate frequency metal pad 106. That is, the upper surface of the intermediate frequency anti-interference metal block 103 is flush with the upper surface of the high frequency anti-interference metal block 104, and the upper surface of the intermediate frequency anti-interference metal block 103 is flush with the lower edge of the feed port 101.

[0069] The intermediate frequency (IF) anti-interference metal block 103 and the high frequency anti-interference metal block 104 can be considered as ideal magnetic conductors, which have a significant suppression effect on the propagation of electromagnetic waves in the corresponding frequency band, while having no effect on electromagnetic waves in other frequency bands. Therefore, the two-dimensional metal cavity slot array antenna of this embodiment has IF and high frequency anti-interference capabilities. In addition, since the feed cavity adopts a metal waveguide structure, and the waveguide has an inherent cutoff frequency property, electromagnetic waves below the corresponding frequency cannot be transmitted in it. Therefore, the antenna of this embodiment also has low frequency anti-interference capabilities.

[0070] This invention endows the antenna with anti-interference capability in multiple different frequency bands by embedding a simple anti-interference periodic structure in the feed cavity. Compared with the traditional form of cascading filters at the antenna end, the antenna of this invention can effectively avoid cascading losses and reduce the size of the system to a certain extent.

[0071] See Figures 20 to 24The radiation cavity includes a metal frame 3 and a second cover plate 401 located on top of the metal frame 3. The bottom of the metal frame 3 is close to the upper surface of the first cover plate 201. Sixteen radiation slots 402 are arranged in a 4×4 array on the second cover plate 401. Along the width direction of the feed cavity 102, multiple radiation tuning metal blocks 403 are equally spaced at the bottom of the second cover plate 401. The radiation tuning metal blocks 403 are staggered on both sides of the radiation slots 402.

[0072] Polarization conversion structures possess excellent circular polarization radiation capability, and due to their uneven surface, they can also improve the antenna's scattering characteristics to some extent. (See also...) Figures 20 to 27 The polarization conversion structure 5 comprises 32 basic units. Figure 29 This is a perspective view of the basic unit of the polarization conversion structure 5. Each basic unit includes a first polarization conversion metal block 501, a second polarization conversion metal block 502, and a third polarization conversion metal block 503. The dimensions of the three metal blocks are random and can be adjusted appropriately according to the operating frequency requirements of different antennas. In this embodiment, the first polarization conversion metal block 501 and the second polarization conversion metal block 502 have the same height but different widths, while the height and width of the third polarization conversion metal block 503 are different from those of the first polarization conversion metal block 501 and the second polarization conversion metal block 502. All three metal blocks are located on top of the second cover plate 401, and their end faces are closely attached to form a stepped shape.

[0073] The first end face 5011 of the first polarization conversion metal block 501 is closely attached to the second end face 5021 of the second polarization conversion metal block 502. The third end face 5022 of the second polarization conversion metal block 502 is closely attached to the fourth end face 5031 of the third polarization conversion metal block 503. The first side face 5012 of the first polarization conversion metal block 501 is flush with the second side face 5023 of the second polarization conversion metal block 502 and the third side face 5032 of the third polarization conversion metal block 503. The end face of the first polarization conversion metal block 501 that faces the first end face 5011 is the fifth end face. The end face of the third polarization conversion metal block 503 that faces the fourth end face 5031 is the sixth end face. (Continue to the next section...) Figure 25Thirty-two basic units are evenly distributed on both sides of the radiation slot 104. Four basic units are located on each side of the four radiation slots 402 along the Y direction. Two basic units are placed close together along the Y direction. Taking two basic units as an example, when the first and second basic units are placed close together, the fifth end face of the first polarization conversion metal block 501 in the first basic unit is close to the sixth end face of the third polarization conversion metal block 503 in the second basic unit. The polarization conversion structure 5 of this invention has a simple structure, is easy to manufacture, and has excellent performance. Furthermore, the uneven surface of the polarization conversion structure can improve the scattering characteristics of the antenna to a certain extent. The close contact of the end faces of the three metal blocks increases the strength of the antenna structure and provides good protection against antenna deformation.

[0074] Each basic unit is stepped, and multiple basic units are arranged on both sides of the radiation slot 402 to form an undulating topography, giving the antenna array a rough, uneven topography. According to the theory of diffuse reflection of electromagnetic waves, when electromagnetic waves irradiate a rough surface, the incident electromagnetic waves can produce a phase difference at the interface, and the scattered energy can be distributed in a multi-angle manner, resulting in diffuse reflection and weakening of reflection, thereby effectively improving the scattering characteristics of the antenna. Based on this characteristic, the antenna structure of the present invention has the characteristic of weak electromagnetic reflection, that is, the antenna structure has the characteristic of reducing RCS, and has great application prospects in the field of electromagnetic stealth design. The polarization conversion structure 5 is an open structure. The open structure does not have the problem of electromagnetic wave transmission cutoff, because when the electromagnetic wave frequency is low, the four-sided closed structure may have transmission cutoff. Compared with the four-sided closed structure, the open structure is more conducive to widening the working bandwidth. In addition, the open structure is more conducive to antenna heat dissipation, easier to machine, and can reduce the movement path of the machining tool in the vertical direction, reducing manufacturing costs.

[0075] When the antenna is transmitting, the electromagnetic signal is input into the feed cavity 102 through the feed port 101, enters the radiation cavity through the coupling slot 202, and then radiates linearly polarized electromagnetic waves outward through the radiation slot 402. After passing through the polarization conversion structure 5, the linearly polarized electromagnetic waves are decomposed into a set of orthogonal components of equal amplitude, with a 90-degree phase difference between the two components, forming circular polarization and radiating into space. When the antenna is receiving, the process is exactly the reverse of the transmitting process. (See also...) Figures 33 to 35 The two-dimensional metal cavity slot array antenna has good impedance matching characteristics within the operating frequency band and three anti-interference frequency bands outside the operating frequency band. The antenna has good circular polarization characteristics within the operating frequency band. Compared with the two-dimensional metal cavity slot array antenna with a smooth surface, the scattering characteristics of the two-dimensional metal cavity slot array antenna with a "rough" surface are adjusted to a certain extent.

[0076] The antenna of this invention features a flat structure, making it extremely convenient for array applications. The antenna can be manufactured using milling technology, a mature process with high reliability, wide application range, and low cost. This invention not only solves the problems of anti-interference and circular polarization requirements for two-dimensional metal cavity slot array antennas, but also boasts excellent performance, simple structure, and ease of manufacturing.

[0077] The polarization conversion structure 5 of this invention is set as an open structure. Compared with the closed structure with cavity, the electromagnetic waves of the open structure are easy to diverge and are not easy to form directional radiation, resulting in lower directional radiation gain. To address this problem, this invention improves the directional radiation gain by rationally designing and optimizing the height and width of the first polarization conversion metal block 501, the second polarization conversion metal block 502, and the third polarization conversion metal block 503, thereby improving the circular polarization radiation performance of the antenna. Height primarily affects the phase of the electromagnetic wave component, while width primarily affects the amplitude of the electromagnetic wave component. In this embodiment, the height (along the Z direction) of the first polarization conversion metal block 501 and the second polarization conversion metal block 502 is the same, approximately half a working wavelength, while the height of the third polarization conversion metal block 503 is approximately one-eighth of the working wavelength. The length (along the Y direction) of the first polarization conversion metal block 501, the second polarization conversion metal block 502, and the third polarization conversion metal block 503 is the same, while their widths (along the X direction) are different. By adjusting the widths of the first polarization conversion metal block 501, the second polarization conversion metal block 502, and the third polarization conversion metal block 503, impedance matching and circular polarization performance can be adjusted.

[0078] Example 2

[0079] The difference between this embodiment and Embodiment 1 is that this embodiment uses the two-dimensional metal cavity slot array antenna of Embodiment 1 as an independent antenna element to construct antenna arrays of different sizes. See [link to previous embodiment]. Figure 36 This embodiment takes a 2×4 scale antenna array as an example to introduce the array of a two-dimensional metal cavity slot array antenna. The antenna array can be a planar array or a coarse array.

[0080] like Figure 37 and Figure 38 As shown, the antenna array adopts a planar layout and includes eight two-dimensional metal cavity slot array antennas, namely antenna element one to antenna element eight. The eight two-dimensional metal cavity slot array antennas are closely combined to form a 2×4 array with their upper surfaces flush, that is, the upper surfaces of antenna element one to antenna element eight are flush. The feed ports 101 of the four two-dimensional metal cavity slot array antennas in each row are located on the same side, and the rear ends of the feed cavities 102 of the two-dimensional metal cavity slot array antennas in adjacent rows are closely aligned.

[0081] like Figure 39 and Figure 40As shown, the antenna array employs a coarse arrangement and includes eight two-dimensional metal cavity slot array antennas. These eight antennas are tightly combined to form a 2×4 array, with the upper surfaces of any two adjacent antennas not flush. The upper surfaces of antenna elements one, three, six, and eight are higher than the upper surfaces of antenna elements two, four, five, and seven. The feed ports 101 of the four antennas in each row are located on the same side, and the rear ends of the feed cavities 102 of adjacent rows are closely fitted together with a certain height difference. By arranging the two-dimensional metal cavity slot array antennas in a coarse, undulating shape, the "roughness" of the large-scale array surface is further improved, thereby effectively improving the antenna's scattering characteristics.

[0082] It should be noted that this embodiment uses a 2×4 antenna array as an example only, and professionals can make any extensions and improvements based on it. At the same time, for the "rough array" of the 2×4 antenna array, only one height scheme is provided. Professionals can design each antenna element to its own appropriate height according to the actual situation, thereby further optimizing the "roughness" of the large-scale array surface.

[0083] This invention not only provides a "rough surface" design scheme for antenna elements, but also a "rough array" design scheme for large-scale arrays, which has significant benefits for adjusting the scattering performance of metal cavity slot antenna elements and their arrays. Based on milling technology, large-scale arrays based on this antenna element can be processed as a whole, rather than processing the elements independently and then splicing them together. This method can ensure processing accuracy and reduce processing costs.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A functional composite two-dimensional metallic cavity slot array antenna, characterized in that: The device includes a feeding cavity, a first cover plate at the top of the feeding cavity, a radiation cavity above the first cover plate, and a polarization conversion structure. The feeding cavity contains multiple sets of periodic intermediate-frequency (IF) and high-frequency (HF) anti-interference metal blocks. Each set of IF and HF anti-interference metal blocks is alternately arranged along the length of the first cover plate. The upper surfaces of the IF and HF anti-interference metal blocks are flush with each other, and the upper surfaces of the IF and HF anti-interference metal blocks are flush with the lower edge of the feeding port. A coupling seam on the first cover plate communicates with the radiation cavity. A radiation slit is opened at the top of the radiation cavity. The radiation cavity includes a metal frame and a second cover plate at the top of the metal frame. The polarization conversion structure is arranged in a stepped and open manner on both sides of the radiation slit, forming an undulating shape. Each basic unit of the polarization conversion structure includes a first polarization conversion metal block, a second polarization conversion metal block, and a third polarization conversion metal block. All three polarization conversion metal blocks are located at the top of the second cover plate, and their end faces are tightly attached to form a stepped shape.

2. The functional composite two-dimensional metallic cavity slot array antenna according to claim 1, characterized in that: When the antenna is transmitting, the electromagnetic signal is fed into the feed cavity, enters the radiation cavity through the coupling slot, and then radiates linearly polarized electromagnetic waves outward through the radiation slot. After passing through the polarization conversion structure, the linearly polarized electromagnetic waves are decomposed into a set of orthogonal components with equal amplitudes and a 90-degree phase difference between the two components, forming circular polarization and radiating into space. When the antenna is receiving, the process is exactly the opposite of the transmission process.

3. The functional composite two-dimensional metallic cavity slot array antenna according to claim 1, characterized in that: The front end of the feeding cavity is configured as a feeding port protruding from the feeding cavity body, the rear end of the feeding cavity is closed, and four coupling seams are equally spaced along the long side central axis of the first cover plate. Four feeding tuning metal blocks are equally spaced along the bottom long side central axis of the first cover plate, and the feeding tuning metal blocks are distributed on one side of the coupling seams.

4. The functional composite two-dimensional metallic cavity slot array antenna according to claim 2, characterized in that: The 32 intermediate frequency anti-interference metal blocks are divided into 8 groups. The 4 intermediate frequency anti-interference metal blocks in each group are evenly spaced on the intermediate frequency metal pad along the width direction of the first cover plate. The 128 high frequency anti-interference metal blocks are divided into 8 groups. The 16 high frequency anti-interference metal blocks in each group form a 2×8 array arranged on the high frequency metal pad.

5. The functional composite two-dimensional metallic cavity slot array antenna according to claim 1, characterized in that: The bottom of the metal frame is close to the upper surface of the first cover plate. Sixteen radiation slots are arranged in a 4×4 array on the second cover plate. Along the width direction of the feed cavity, multiple radiation tuning metal blocks are equally spaced at the bottom of the second cover plate. The radiation tuning metal blocks are staggered on both sides of the radiation slots.

6. The functional composite two-dimensional metallic cavity slot array antenna according to claim 1, characterized in that: The polarization conversion structure consists of 32 basic units.

7. The functional composite two-dimensional metallic cavity slot array antenna according to claim 6, characterized in that: The first end face of the first polarization conversion metal block is in close contact with the second end face of the second polarization conversion metal block, the third end face of the second polarization conversion metal block is in close contact with the fourth end face of the third polarization conversion metal block, and the first side face of the first polarization conversion metal block is flush with the second side face of the second polarization conversion metal block and the third side face of the third polarization conversion metal block.

8. The functional composite two-dimensional metallic cavity slot array antenna according to claim 6, characterized in that: The first and second polarization conversion metal blocks have the same height, each half the working wavelength, while the third polarization conversion metal block has a height of one-eighth the working wavelength.

9. A functional composite two-dimensional metallic cavity slot array antenna array, characterized in that: Using the functional composite two-dimensional metal cavity slot array antenna as described in any one of claims 1-8 as the antenna element, multiple antenna elements are arranged in a planar array, the feed ports of each row of antenna elements are located on the same side, the rear ends of the feed cavities of adjacent rows of antenna elements are closely aligned, and the upper surfaces of all antenna elements are flush.

10. A functional composite two-dimensional metallic cavity slot array antenna array, characterized in that: Using the functional composite two-dimensional metal cavity slot array antenna as described in any one of claims 1-8 as the antenna element, multiple antenna elements are coarsely arranged, the feed ports of each row of antenna elements are located on the same side, the rear ends of the feed cavities of two adjacent rows of antenna elements are closely attached and have a certain height difference, and the upper surfaces of any two adjacent antenna elements are not flush.

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