Double-frequency slot antenna structure with back cavity and design method

Abstract

The invention discloses a double-frequency slot antenna structure with a back cavity and a design method, which are used for an omnidirectional communication system. The antenna can work in two frequency bands, the antenna comprises a disc metal cavity, eight arc-shaped gaps above the cavity, and some metal columns and metal sheets in the middle of the cavity, and the antenna feeds the gaps from the center of the bottom of the cavity in a coaxial probe feeding mode; a filtering mechanism is formed through a metal column and a metal sheet in the middle of the cavity, and high frequency is blocked through low frequency, so that high-band radiation waves are limited in the small cavity in the middle and then are radiated out from four first arc-shaped gaps above, and low-band radiation waves are radiated out from four second arc-shaped gaps above the whole disc cavity after passing through the filtering mechanism; high-frequency energy and low-frequency energy can be separated, different cavity sizes are formed at different frequencies, and working frequency radiation is controlled by combining the length of the gap.

Description

Technical Field

[0001] This invention belongs to the technical field of dual-frequency slot antennas, specifically relating to a dual-frequency slot antenna structure and design method with a back cavity. Background Technology

[0002] With the rapid development of modern communication technology, people have increasingly higher requirements for the performance of communication equipment. From early simple voice communication to today's high-speed data transmission, Internet of Things applications, and complex multimedia communication, more efficient and stable antenna systems are needed. Omnidirectional antennas are widely used in point-to-multipoint communication and are extensively applied in military, aerospace, remote control, and telemetry fields. In existing technologies, omnidirectional antenna radiators are mostly installed above a metal carrier, protruding from the airborne platform. This is because vertically polarized omnidirectional radiating antennas rely mainly on vertical current or its opposite horizontal magnetic current for radiation. Therefore, placing the radiator above a metal carrier in an unobstructed installation environment is beneficial for achieving optimal electrical performance. However, with the development of science and technology, the operating speed of aircraft and vehicles is increasing, and the omnidirectional antennas used in conjunction with them are also evolving from the original protruding type to conformal, stealthy, and embedded designs. Traditional exposed antennas have disadvantages such as occupying space, being easily damaged, and increasing aerodynamic drag, while embedded omnidirectional communication antennas can effectively solve these problems.

[0003] Current research on omnidirectional vertically polarized cavity slot antennas primarily focuses on a single frequency. Simply creating a slot for another frequency within the cavity can lead to impedance mismatch. Existing airborne platform omnidirectional communication and telemetry antennas typically employ monopole antennas, which have a high profile and are unsuitable for conformal applications. Low-profile dual-band antennas are mainly implemented using microstrip structures. They achieve dual-frequency operation through different resonant modes and frequencies of the structure, or achieve dual-frequency omnidirectional radiation based on microstrip technology. The frequencies of both types of antennas are related to the size of the microstrip structure, and due to this limitation, the ratio of operating frequencies cannot be too large.

[0004] Therefore, in view of the above-mentioned problems of existing omnidirectional communication antennas and telemetry and control antennas on airborne platforms, a dual-frequency slot antenna structure and design method with a back cavity is disclosed. Summary of the Invention

[0005] This invention discloses a dual-frequency slot antenna structure and design method with a back cavity, which can separate high-frequency energy and low-frequency energy, form different cavity sizes at different frequencies, and control the radiation of the operating frequency in combination with the slot length.

[0006] This invention is achieved through the following technical solution: A dual-frequency slotted antenna structure with a back cavity includes a disc-shaped metal cavity. A coaxial probe is coaxially disposed at the center of the disc-shaped metal cavity. A dielectric layer is coaxially disposed around the coaxial probe. A filtering mechanism is disposed inside the dielectric layer. A plurality of first arc-shaped slots are evenly distributed circumferentially in the region between the top of the coaxial probe and the filtering mechanism. A plurality of second arc-shaped slots are evenly distributed circumferentially in the region between the top of the filtering mechanism and the top edge of the disc-shaped metal cavity.

[0007] To better realize the present invention, the filtering mechanism further includes a plurality of filtering units evenly distributed in the circumferential direction inside the dielectric layer. The filtering unit includes filtering elements symmetrically arranged vertically, with a gap between the filtering elements on the upper and lower sides.

[0008] To better realize the present invention, the filter further includes a metal patch and a metal pillar, the metal pillar being connected to the top or bottom of the disc metal cavity, and a metal patch being provided at one end of the metal pillar near the middle of the disc metal cavity.

[0009] To better realize the present invention, the metal patch is square and the metal column is cylindrical.

[0010] To better realize the present invention, the side length of the metal patch is less than or equal to 8 mm; the radius of the metal column is less than or equal to 1 mm; and the length of the metal column is less than or equal to 7 mm.

[0011] To better realize the present invention, the first arc-shaped slit is evenly distributed along a circumferential path with a radius of less than or equal to 12 mm in the area between the top of the coaxial probe and the filtering mechanism. The length of the first arc-shaped slit is less than or equal to 27.5 mm and the width is less than or equal to 2 mm.

[0012] To better realize the present invention, the second arc-shaped slit is further provided in the region between the top of the filter mechanism and the top edge of the disc metal cavity along a circumferential path with a radius of less than or equal to 150 mm. The length of the second arc-shaped slit is less than or equal to 204 mm and the width is less than or equal to 7 mm.

[0013] To better realize the present invention, an antenna cover is coaxially fastened to the top of the disc metal cavity, and an extension is provided at the top edge of the disc metal cavity, with a plurality of fixing screws evenly distributed along the circumferential direction on the extension.

[0014] A design method for a dual-frequency slotted antenna with a back cavity, used to design a dual-frequency slotted antenna structure, includes the following steps: Step 1: Design a high-frequency cavity slot antenna, set up a first cylindrical cavity, and open several evenly distributed first arc-shaped slots on the top of the first cylindrical cavity. Use simulation software to adjust the expected high-frequency radiation curve. Step 2: Design a low-frequency cavity slot antenna, set up a second cylindrical cavity, and open several evenly distributed second arc-shaped slots above the second cylindrical cavity. Use simulation software to adjust the expected low-frequency radiation curve. Step 3: Distribute the filter mechanism evenly in the area between the first arc-shaped gap and the second arc-shaped gap, and use simulation software to obtain the expected filter characteristic curve; Step 4: Coaxially couple the first arc-shaped gap, the second arc-shaped gap, and the filtering mechanism to the inside of the disc metal cavity, and replace the cavity wall of the second cylindrical cavity with the filtering mechanism from step 3.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: The antenna of this invention can operate in two frequency bands. Through the filtering mechanism formed by the metal pillar and metal sheet in the middle of the disc-shaped metal cavity, low-frequency waves are passed through and high-frequency waves are blocked. In this way, the high-frequency radiation waves are confined in the small cavity in the middle and then radiated out from the four first arc-shaped slots above. The low-frequency radiation waves pass through the filtering mechanism and then radiate out from the four second arc-shaped slots above. This separates the high-frequency energy and low-frequency energy, forming different cavity sizes at different frequencies. Combined with the slot length, the operating frequency radiation is controlled, providing a design scheme for multi-frequency cavity-backed slotted antennas and effectively solving the impedance mismatch problem of multi-frequency cavity-backed slotted antennas. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of a dual-frequency slot antenna. Figure 2 This is a side view of a dual-frequency slot antenna structure. Figure 3 This is a top view of a dual-frequency slot antenna structure. Figure 4 This is a schematic diagram of the filter unit. Figure 5 This is a schematic diagram of the filter mechanism; Figure 6 The characteristic curve of C-band S11; Figure 7 The characteristic curve of S11 in the UHF band; Figure 8 The radiation pattern of the H-plane in the C-band; Figure 9 This is the H-plane radiation pattern for the UHF band.

[0017] Wherein: 1-First arc-shaped slit; 2-Second arc-shaped slit; 3-Filtering mechanism; 4-Coaxial probe; 5-Antenna radome; 6-Disc metal cavity; 7-Fixing screw; 31-Metal patch; 32-Metal pillar. Detailed Implementation

[0018] Example 1: This embodiment discloses a dual-frequency slot antenna structure with a back cavity, such as... Figures 1-3 As shown, the device includes a disc-shaped metal cavity 6. A coaxial probe 4 is coaxially disposed at the center of the disc-shaped metal cavity 6. A dielectric layer is coaxially disposed around the coaxial probe 4. A filter mechanism 3 is disposed inside the dielectric layer. A plurality of first arc-shaped gaps 1 are evenly distributed circumferentially in the area between the top of the coaxial probe 4 and the filter mechanism 3. A plurality of second arc-shaped gaps 2 are evenly distributed circumferentially in the area between the top of the filter mechanism 3 and the top edge of the disc-shaped metal cavity 6.

[0019] The first arc-shaped slit 1, serving as a high-frequency arc-shaped radiation slit, consists of four evenly distributed first arc-shaped slits 1 extending from the upper part of the disc-shaped metal cavity 6 near its center. The length of the first arc-shaped slit 1 is approximately half the high-frequency wavelength. The second arc-shaped slit 2, serving as a low-frequency arc-shaped radiation slit, consists of four evenly distributed second arc-shaped slits 2 extending from the edge of the disc-shaped metal cavity 6. The length of the second arc-shaped slit 2 is approximately half the low-frequency wavelength. A filter mechanism 3 is evenly distributed between the first arc-shaped slit 1 and the second arc-shaped slit 2. The filter mechanism 3, formed by metal pillars and metal sheets, is evenly arranged around the center and finally embedded in the dielectric layer.

[0020] The height of the disc metal cavity 6 is h1=17mm, the bottom diameter of the disc metal cavity 6 is D1=260mm, the top diameter of the disc metal cavity 6 is R3=150mm, and the top of the disc metal cavity 6 has an extension of 25mm for installing the fixing screw 7, that is, the total top radius of the disc metal cavity 6 is R2=175mm.

[0021] Four first arc-shaped slots 1 are evenly distributed circumferentially at a distance of 150 mm from the center of the upper edge of the circular metal cavity 6, with an arc length of 204 mm and a width of 7 mm. Four arc-shaped slots 2 are located at a distance of 21 mm from the center of the circular metal cavity 6, with a slot length of 27.5 mm and a width of 2 mm. The radome 5 above the cavity has a height of h2 = 2 mm and a radius of 175 mm. Furthermore, an antenna radome 5 is coaxially fastened to the top of the disc-shaped metal cavity 6. An extension is provided at the top edge of the disc-shaped metal cavity 6, and several fixing screws 7 are evenly distributed along the circumference of the extension. The height of the antenna radome 5 is h2 = 2 mm, and the radius of the antenna radome 5 is 175 mm.

[0022] The first arc-shaped slot 1 and the second arc-shaped slot 2 are both uniformly distributed circumferentially. The filtering mechanism 3 includes 16 filtering units evenly distributed circumferentially. The filtering units are uniformly distributed in the Rogers RT / duroid 5880 dielectric layer, which is a ring-shaped column. The antenna is fed from the center of the bottom of the cavity to the slot by a coaxial probe 4.

[0023] A method for designing a dual-frequency slotted antenna with a back cavity includes the following steps: Step 1: Design a high-frequency cavity slot antenna, set up a first cylindrical cavity, and open several evenly distributed first arc-shaped slots 1 above the first cylindrical cavity. Use simulation software to adjust the expected high-frequency radiation curve. Step 2: Design a low-frequency cavity slot antenna, set up a second cylindrical cavity, and open several evenly distributed second arc-shaped slots 2 above the second cylindrical cavity. Use simulation software to adjust the expected low-frequency radiation curve. Step 3: Distribute the filter mechanism 3 evenly in the area between the first arc-shaped gap 1 and the second arc-shaped gap 2, and use simulation software to generate the expected filter characteristic curve. Step 4: Coaxially couple the first arc-shaped gap 1, the second arc-shaped gap 2, and the filter mechanism 3 to the inside of the disc metal cavity 6, and replace the cavity wall of the second cylindrical cavity with the filter mechanism 3 from step 3.

[0024] The simulation results for the antenna are as follows: Figures 6-9 As shown, where Figure 6 The C-band -10dB bandwidth shown is 4.66GHz-4.79GHz; Figure 7 The UHF band shown has a -10dB bandwidth of 826MHz-862MHz; Figure 8 and Figure 9 The images show the horizontal radiation patterns for the C-band and UHF bands, respectively, with gains greater than -5 dBi.

[0025] The rest of this embodiment is the same as that of Embodiment 1, so it will not be described again.

[0026] Example 2: This embodiment discloses a dual-frequency slot antenna structure with a back cavity, which is an improvement on Embodiment 1, such as... Figure 4 and Figure 5 As shown, the filtering mechanism 3 includes several filtering units evenly distributed circumferentially inside the dielectric layer. Each filtering unit includes filtering components symmetrically arranged vertically, with gaps between the filtering components on the upper and lower sides.

[0027] Furthermore, the filter includes a metal patch 31 and a metal post 32. The metal post 32 is connected to the top or bottom of the disc metal cavity 6, and the metal patch 31 is provided at one end of the metal post 32 near the middle of the disc metal cavity 6.

[0028] Two sets of filters arranged symmetrically, one above the other, constitute a filter unit. The metal patches 31 in the upper and lower filters are positioned opposite each other with a gap. The top of the upper metal patch 31 is connected to the top of the circular metal cavity 6 via an upper metal post 32, and the bottom of the lower metal patch 31 is connected to the bottom of the circular metal cavity 6 via a lower metal post 32. The metal patch 31 is square; the metal post 32 is cylindrical; the side length of the metal patch 31 is 8mm; the radius of the metal post 32 is 1mm; and the length of the metal post 32 is 7mm.

[0029] The rest of this embodiment is the same as that of Embodiment 1, so it will not be described again.

[0030] Example 3: This embodiment discloses a dual-frequency slot antenna structure with a back cavity, which is an improvement on embodiment 1 or 2. The first arc-shaped slot 1 is evenly distributed in the area between the top of the coaxial probe 4 and the filter mechanism 3 along a circumferential path with a radius of 12 mm. The length of the first arc-shaped slot 1 is 27.5 mm and the width is 2 mm.

[0031] The second arc-shaped slit 2 is evenly distributed along a circumferential path with a radius of 150 mm in the area between the top of the filter mechanism 3 and the top edge of the disc metal cavity 6. The length of the second arc-shaped slit 2 is 204 mm and the width is 7 mm.

[0032] The above are preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A dual-frequency slotted antenna structure with a back cavity, comprising a disk-shaped metal cavity (6), characterized in that, A coaxial probe (4) is coaxially disposed at the center of the disc metal cavity (6). A dielectric layer is coaxially disposed around the coaxial probe (4). A filter mechanism (3) is disposed inside the dielectric layer. A number of first arc-shaped gaps (1) are evenly distributed circumferentially in the area between the top of the coaxial probe (4) and the filter mechanism (3). A number of second arc-shaped gaps (2) are evenly distributed circumferentially in the area between the top of the filter mechanism (3) and the top edge of the disc metal cavity (6).

2. The dual-frequency slot antenna structure with a back cavity according to claim 1, characterized in that, The filtering mechanism (3) includes several filtering units evenly distributed in the circumferential direction inside the dielectric layer. Each filtering unit includes filtering components symmetrically arranged on the upper and lower sides, with a gap between the filtering components on the upper and lower sides.

3. The dual-frequency slot antenna structure with a back cavity according to claim 2, characterized in that, The filter includes a metal patch (31) and a metal post (32). The metal post (32) is connected to the top or bottom of the disc metal cavity (6). The metal post (32) is provided with a metal patch (31) at one end near the middle of the disc metal cavity (6).

4. The dual-frequency slot antenna structure with a back cavity according to claim 3, characterized in that, The metal patch (31) is square; the metal column (32) is cylindrical.

5. The dual-frequency slot antenna structure with a back cavity according to claim 4, characterized in that, The side length of the metal patch (31) is less than or equal to 8 mm; the radius of the metal post (32) is less than or equal to 1 mm; and the length of the metal post (32) is less than or equal to 7 mm.

6. A dual-frequency slot antenna structure with a back cavity according to any one of claims 1-5, characterized in that, The first arc-shaped slit (1) is evenly distributed along a circumferential path with a radius of less than or equal to 12 mm in the area between the top of the coaxial probe (4) and the filter mechanism (3). The length of the first arc-shaped slit (1) is less than or equal to 27.5 mm and the width is less than or equal to 2 mm.

7. A dual-frequency slotted antenna structure with a back cavity according to any one of claims 1-5, characterized in that, The second arc-shaped slit (2) is evenly distributed along a circumferential path with a radius of less than or equal to 150 mm in the area between the top of the filter mechanism (3) and the top edge of the disc metal cavity (6). The length of the second arc-shaped slit (2) is less than or equal to 204 mm and the width is less than or equal to 7 mm.

8. A dual-frequency slotted antenna structure with a back cavity according to any one of claims 1-5, characterized in that, The top of the disc metal cavity (6) is coaxially fastened with an antenna cover (5), and an extension is provided at the top edge of the disc metal cavity (6). Several fixing screws (7) are evenly distributed along the circumference of the extension.

9. A design method for a dual-frequency slotted antenna with a back cavity, used to design the dual-frequency slotted antenna structure according to any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Design a high-frequency cavity slot antenna, set up a first cylindrical cavity, and open several uniformly distributed first arc-shaped slots above the first cylindrical cavity (1), and use simulation software to get the expected high-frequency radiation curve; Step 2: Design a low-frequency cavity slot antenna, set up a second cylindrical cavity, and open several evenly distributed second arc-shaped slots above the second cylindrical cavity (2). Use simulation software to get the expected low-frequency radiation curve. Step 3: Distribute the filter mechanism (3) evenly in the area between the first arc-shaped gap (1) and the second arc-shaped gap (2), and use simulation software to get the expected filter characteristic curve; Step 4: Coaxially couple the first arc-shaped gap (1), the second arc-shaped gap (2), and the filtering mechanism (3) to the inside of the disc metal cavity (6), and replace the cavity wall of the second cylindrical cavity with the filtering mechanism (3) from step 3.

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