A high-isolation plastic metallized waveguide slot antenna

Abstract

The application discloses a high-isolation plastic metalized waveguide slot antenna, which comprises a fixed back plate, a transmitting antenna, a transceiving isolation structure and a receiving antenna arranged on the fixed back plate. The transmitting antenna comprises one waveguide slot antenna unit and is used for transmitting electromagnetic signals. The transceiving isolation structure is arranged between the transmitting antenna and the receiving antenna and is used for inhibiting spatial wave coupling between the transmitting antenna and the receiving antenna. The receiving antenna comprises eight waveguide slot antenna units arranged according to predetermined positions and is used for receiving echo signals of a target. The application has the characteristics of high isolation while ensuring the gain requirement, and has the advantages of light weight and low cost.

Description

Technical Field

[0001] This invention pertains to antenna technology, specifically a high-isolation plastic-metallized waveguide slot antenna. Background Technology

[0002] Plastic metallized antennas achieve their function by electroplating a plastic surface. Compared to traditional metal antennas, plastic metallized antennas offer advantages such as the ability to combine precision injection molding processes, high processing accuracy, one-piece molding, light weight, good consistency, improved overall antenna reliability, and reduced overall cost. Utilizing plastic metallized materials makes it easier to achieve lightweight, low-cost, and mass production of waveguide array antennas.

[0003] A waveguide slot antenna is an antenna formed by etching various slots into a waveguide. Commonly used slots include longitudinal slots on the wide side, angled slots on the narrow side, and transverse slots on the wide side. Waveguides can shield electromagnetic fields; when various types of slots are etched into the metal walls of the waveguide, these slots can couple energy through the field inside the waveguide. The dominant mode (TE)... 10 The current can be divided into two components: transverse and longitudinal. The transverse component exhibits a cosine distribution along the wide metal wall of the waveguide, reaching its maximum value at the center. On the narrow metal wall, only the transverse current exists, exhibiting a uniform distribution. When the direction of the slit forms a certain angle with the direction of the current line, the current line will be cut by the slit in the metal wall, interrupting the current transmission. The current then continues to propagate as a displacement current. The slit can be excited in this way, radiating electromagnetic waves.

[0004] Due to its compact structure, high radiation efficiency, and easy control of aperture amplitude distribution, waveguide slot antennas are widely used in shipborne, missile-borne, and navigation radar systems, as well as in microwave communications.

[0005] Reference 1 (A. Garcia-Tejero, M. Burgos-Garcia and F. Merli, “Broadband Metalized Plastic Waveguide Antenna with Robust Isolation Interface at 77 GHz,” in IEEE Antennas and Wireless Propagation Letters.) designs a plastic-metalized waveguide antenna for automotive radar in the 76-81 GHz range. The antenna comprises three transmitting antennas and four receiving antennas, with each antenna element consisting of eight linearly arranged elements. The entire antenna is fabricated using injection molding, metallization, and welding processes, achieving an impedance bandwidth of 20.1%. Compared to traditional dielectric substrate-based antennas, this design and manufacturing method offers advantages such as lower cost and higher precision. Reference 2 (L.Ma, M.Li, P.Chen, H.Zhang and X.Yu, “Essay of Low Sidelobe Waveguide Slot Antenna Arrays,” 2020 13th UK-Europe-China Workshop on Millimeter-Waves and Terahertz Technologies (UCMMT), Tianjin, China, 2020, pp.1-3.) proposes a slotted waveguide array antenna for radar target detection, operating at frequencies of 15.14-15.24 GHz. The antenna array consists of four 32-slot waveguide slotted antennas arranged side-by-side, fed by a 1-to-8 waveguide power divider. This antenna array has a high gain of 27 dB and a low sidelobe of -24 dB. However, the antenna is made entirely of metal, which has the disadvantages of being heavier and having higher insertion loss compared to plastic-based metal antennas. Summary of the Invention

[0006] The purpose of this invention is to provide a high-isolation plastic metallized waveguide slot antenna.

[0007] The technical solution to achieve the purpose of this invention is as follows: a high-isolation plastic metallized waveguide slot antenna, including a fixed back plate and a transmitting antenna, a transmitting / receiving isolation structure, and a receiving antenna disposed on the fixed back plate. The transmitting antenna includes one waveguide slot antenna element for transmitting electromagnetic signals. The transmitting / receiving isolation structure is placed between the transmitting and receiving antennas to suppress spatial wave coupling between the transmitting and receiving antennas. The receiving antenna includes eight waveguide slot antenna elements arranged in a predetermined position for receiving echo signals from the target.

[0008] Preferably, the waveguide slot antenna unit includes: a waveguide structure, a coaxial-to-waveguide structure, and a coaxial probe. The bottom surface of the waveguide structure is connected to the coaxial-to-waveguide structure, and the coaxial probe extends into the bottom surface of the coaxial-to-waveguide structure. The top surface of the coaxial-to-waveguide structure is provided with two waveguide slot antenna radiation slots parallel to the wide side of the waveguide structure. Inside the coaxial-to-waveguide structure, a square ridge is provided on each side of each waveguide slot antenna radiation slot.

[0009] Preferably, the coaxial waveguide structure is an L-shaped structure.

[0010] Preferably, the two waveguide slot antenna radiating slots are 26mm long, 4mm wide, and 2.5mm deep.

[0011] Preferably, the transceiver isolation structure is a plastic-metallized isolation wall with a choke groove of a preset size.

[0012] Preferably, the transceiver isolation structure includes a first rectangle and a second rectangle, which together form a T-shaped wall; three choke slots parallel to the long side are etched in the middle of the first rectangle, and three choke slots parallel to the long side of the second rectangle are etched in the middle of the second rectangle.

[0013] Preferably, the spacing between adjacent choke slots is 25mm, the depth of each choke slot is 16mm, and the width is 20mm.

[0014] Preferably, with the transmitting antenna as the origin of the coordinate system, the direction of the slot parallel to the waveguide as the x-direction, and the direction perpendicular to the slot as the y-direction, and with 1 wavelength λ as the unit, the positions of the 8 receiving antennas are (0.5λ, 5λ), (1.5λ, 5λ), (3λ, 5λ), (4.5λ, 5λ), (5λ, 5λ), (5.5λ, 4.5λ), (5λ, 3.5λ), and (5λ, 0.5λ).

[0015] Compared with existing technologies, the significant advantages of this invention are: It uses plastic metallized materials, resulting in low loss, low cost, light weight, and ease of mass production. The waveguide antenna employs a narrow-sided slot with alternating square ridges on both sides of the slot, reducing cross-polarization and improving the radiation efficiency of the waveguide slot antenna. An isolation structure is designed between the receiving and transmitting antennas, effectively reducing spatial wave coupling effects and achieving high isolation between the transmitting and receiving antennas.

[0016] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural schematic diagram of a high-isolation plastic-metallized waveguide slot antenna.

[0018] Figure 2 This is a schematic diagram of a waveguide slot antenna element.

[0019] Figure 3 This is a schematic diagram of the isolation structure of the present invention.

[0020] Figure 4 This is a top view of a waveguide slot antenna element.

[0021] Figure 5 This is a cross-sectional schematic diagram of an embodiment of the high-isolation plastic metallized waveguide slot antenna element of the present invention.

[0022] Figure 6 This is a cross-sectional schematic diagram of an embodiment of the high-isolation plastic metallized waveguide slot antenna unit coaxial rotating waveguide structure of the present invention.

[0023] Figure 7 This is a top-level view of one embodiment of the high-isolation plastic-metallized waveguide slot antenna isolation structure of the present invention.

[0024] Figure 8 This is a side view of an embodiment of the high-isolation plastic-metallized waveguide slot antenna isolation structure of the present invention.

[0025] Figure 9 The return loss of the high-isolation plastic metallized waveguide slot antenna of the present invention.

[0026] Figure 10 This refers to the transmit / receive isolation of the high-isolation plastic metallized waveguide slot antenna of the present invention.

[0027] Figure 11 This is the azimuth antenna radiation pattern of the high-isolation plastic metallized waveguide slot antenna of the present invention.

[0028] Figure 12 This is the elevation antenna radiation pattern of the high-isolation plastic metallized waveguide slot antenna of the present invention. Detailed Implementation

[0029] like Figures 1-8 As shown, a high-isolation plastic metallized waveguide slot antenna includes a fixed backplate (4) and a transmitting antenna (1), a transmitting / receiving isolation structure (2), and a receiving antenna (3) disposed on the fixed backplate (4). The transmitting antenna (1) includes one waveguide slot antenna element for transmitting electromagnetic signals. The transmitting / receiving isolation structure is placed between the transmitting and receiving antennas to suppress spatial wave coupling between the transmitting antenna (1) and the receiving antenna (3). The receiving antenna (3) includes eight waveguide slot antenna elements arranged in predetermined positions for receiving echo signals from a target. The waveguide slot antenna elements are made of metallized plastic and are manufactured using injection molding, electroplating, and welding processes.

[0030] In a further embodiment, the waveguide slot antenna unit includes: a waveguide structure (14), a coaxial-to-waveguide structure (13), and a coaxial probe. The bottom surface of the waveguide structure (14) is connected to the coaxial-to-waveguide structure (13), and the coaxial probe extends into the bottom surface of the coaxial-to-waveguide structure (13). The top surface of the coaxial-to-waveguide structure (13) is provided with two waveguide slot antenna radiation slots (11) parallel to the wide side of the waveguide structure. Inside the coaxial-to-waveguide structure (13), each waveguide slot antenna radiation slot (11) has a square ridge (12) on each side. The position of the waveguide slot antenna radiation slot (11) is used to control the phase distribution of the antenna radiation amplitude. The square ridges (12) on both sides of the waveguide slot antenna radiation slot (11) are used to change the excitation current in the waveguide, reduce the cross-polarization between slot elements, and improve the radiation efficiency of the waveguide slot antenna.

[0031] Specifically, the waveguide slot antenna radiating slot (11) has a spacing of d1, a length of L3, a width of W3, and a depth of t3.

[0032] Specifically, four square ridges are provided, one on each side of each waveguide slot antenna radiating slot (11). The two square ridges on each side of the waveguide slot antenna radiating slot (11) are located diagonally opposite to each other, closely attached to the inner wall of the wide side of the waveguide, and the distance between them and the edge of the waveguide slot antenna radiating slot (11) is 0.5 mm. Their function is to change the excitation current in the waveguide and improve the radiation efficiency of the waveguide slot antenna.

[0033] In a further embodiment, with the transmitting antenna as the origin of the coordinate system, the direction of the slot in the parallel waveguide as the x-direction, and the direction perpendicular to the slot as the y-direction, and with 1 wavelength λ as the unit, the positions of the 8 receiving antennas are (0.5λ, 5λ), (1.5λ, 5λ), (3λ, 5λ), (4.5λ, 5λ), (5λ, 5λ), (5.5λ, 4.5λ), (5λ, 3.5λ), and (5λ, 0.5λ).

[0034] Furthermore, the waveguide slot antenna element has a length of L1, a width of W1, a height of H1, and a thickness of t1.

[0035] In a further embodiment, the isolation structure is a plastic metallized isolation wall with etched choke grooves.

[0036] Specifically, the isolation structure consists of a T-shaped wall composed of a first rectangle (21) with a length of 150 mm and a width of 110 mm and a second rectangle (22) with a length of 230 mm and a width of 105 mm. The overall height of the T-shaped wall is 90 mm. Six rectangular choke slots of equal width are etched on the upper surface of the isolation wall. Three choke slots parallel to the long side of the first rectangle (21) are etched in the middle, and these three choke slots are arranged linearly. Three choke slots parallel to the long side of the second rectangle (22) are etched in the middle, and these three choke slots are also arranged linearly.

[0037] The isolation structure has a length of L2, a width of W2, a height of H2, and a choke groove width of W. t With a depth of t2, it is located between the transmitting and receiving antennas to suppress the coupling effect between the antennas and improve the isolation between the receiving and transmitting antennas.

[0038] Specifically, the square ridges within the waveguide are alternately arranged on both sides of the slot, at a distance of d2 from the slot, with a side length of a. Their function is to change the excitation current within the waveguide, reduce cross-polarization between the radiating slots, and improve the overall radiation efficiency of the antenna.

[0039] Specifically, the coaxial probe extends from the bottom surface of the coaxial-to-waveguide structure (13) with a probe radius of R1, a probe length of L4 extending into the waveguide, and a distance of d3 from the short surface of the waveguide.

[0040] This invention reduces the return loss of the waveguide slot antenna by optimizing the width W3 and depth t3 of the waveguide slot, the length L4 of the coaxial probe extending into the waveguide, and the distance d3 between the probe and the short-circuit surface of the waveguide. It also improves the antenna radiation pattern by optimizing the side length a of the square ridges on both sides of the slot and the spacing d1 between the slot elements. Furthermore, it reduces the spatial coupling effect between the transmitting and receiving antennas and improves the isolation between them by optimizing the height H2 of the isolation structure and the depth t2 of the choke slot.

[0041] In some embodiments, the values ​​of each parameter are shown in Table 1:

[0042] Table 1

[0043]

[0044] This invention reduces the return loss of the waveguide slot antenna by optimizing the width W3 and depth t3 of the waveguide slot, the length L4 of the coaxial probe extending into the waveguide, and the distance d3 between the probe and the short-circuit surface of the waveguide. It also improves the antenna radiation pattern by optimizing the side length a of the square ridges on both sides of the slot and the spacing d1 between the slot elements. Furthermore, it reduces the spatial coupling effect between the transmitting and receiving antennas and improves the isolation between them by optimizing the height H2 of the isolation structure and the depth t2 of the choke slot.

[0045] The present invention will be further explained below with reference to the embodiments.

[0046] Example 1

[0047] like Figure 1 As shown in this embodiment, a high-isolation plastic-metallized waveguide slot antenna includes a transmitting antenna, a receiving antenna, an isolation structure, and a fixing backplate. The transmitting antenna consists of one waveguide slot antenna element, and the receiving antenna consists of eight waveguide slot antenna elements. The isolation structure is a plastic-metallized wall with choke slots of a preset size, located between the transmitting and receiving antennas to improve the isolation between them. The fixing backplate is an aluminum alloy plate used to fix the transmitting antenna, receiving antenna, and isolation structure. The waveguide slot antenna elements are made of metallized plastic and are manufactured using injection molding, electroplating, and welding processes.

[0048] By optimizing the width W3, depth t3, and probe length L4 of the coaxial-to-waveguide structure of the waveguide slot antenna element, as well as the distance d3 between the probe and the short-circuit surface of the waveguide, the return loss of the waveguide slot antenna is reduced. By optimizing the spacing d1 of the slot elements, the beamwidth of the slot waveguide antenna is optimized. The isolation structure is a plastic-metallized isolation wall with linearly arranged choke slots etched on it. By optimizing the height H2 of the isolation wall and the depth t2 of the choke slots, spatial wave coupling between the receiving and transmitting antennas is suppressed, and the isolation between the receiving and transmitting antennas is improved.

[0049] The antenna was simulated and optimized using the simulation software HFSS, resulting in simulation results for a high-isolation plastic metallized waveguide slot antenna.

[0050] This embodiment simulates a high-isolation plastic-metallized waveguide slot antenna. For example... Figure 9 As shown, the antenna's return loss is less than -10dB in the 5.26GHz-5.65GHz range. Figure 10 As shown, the isolation between the receiving antenna and the transmitting antenna at the 5.5 GHz frequency point is 67 dB, 68 dB, 68 dB, 68 dB, 69 dB, 70 dB, 71 dB, and 80 dB, respectively. Figures 11-12 As shown, the high-isolation plastic metallized waveguide slot antenna operates at a frequency of 5.5 GHz, has an antenna gain of 9.6 dB, a 3 dB beamwidth of 35° in the elevation plane, and a 3 dB beamwidth of 84° in the horizontal plane.

Claims

1. A high-isolation plastic metallized waveguide slot antenna, characterized in that, The system includes a fixed backplate (4) and a transmitting antenna (1), a transceiver isolation structure (2), and a receiving antenna (3) mounted on the fixed backplate (4). The transmitting antenna (1) includes one waveguide slot antenna element for transmitting electromagnetic signals. The transceiver isolation structure is positioned between the transmitting and receiving antennas to suppress spatial wave coupling between the transmitting antenna (1) and the receiving antenna (3). The receiving antenna (3) includes eight waveguide slot antenna elements arranged in predetermined positions for receiving echo signals from the target. The waveguide slot antenna unit includes: a waveguide structure (14), a coaxial-to-waveguide structure (13), and a coaxial probe. The bottom surface of the waveguide structure is connected to the coaxial-to-waveguide structure (13). The coaxial probe extends into the bottom surface of the coaxial-to-waveguide structure (13). The top surface of the waveguide structure (14) is provided with two waveguide slot antenna radiation slots (11) parallel to the narrow side of the waveguide structure. Inside the waveguide structure (14), each waveguide slot antenna radiation slot (11) has a square ridge (12) on each side. The transceiver isolation structure is a plastic-metallized isolation wall with a choke groove of a preset size; The transceiver isolation structure includes a first rectangle (21) and a second rectangle (22), which together form a T-shaped wall. Three choke slots parallel to the long side of the first rectangle (21) are etched in the middle, and three choke slots parallel to the long side of the second rectangle (22) are etched in the middle.

2. The high-isolation plastic metallized waveguide slot antenna according to claim 1, characterized in that, The coaxial rotating waveguide structure (13) is an L-shaped structure.

3. The high-isolation plastic metallized waveguide slot antenna according to claim 1, characterized in that, The two waveguide slot antenna radiating slots (11) are 26 mm long, 4 mm wide, and 2.5 mm deep.

4. The high-isolation plastic metallized waveguide slot antenna according to claim 1, characterized in that, The spacing between adjacent choke slots is 25mm, the depth of each choke slot is 16mm, and the width is 20mm.

5. The high-isolation plastic metallized waveguide slot antenna according to claim 1, characterized in that, With the transmitting antenna as the origin, the direction of the slot in the parallel waveguide as the x-direction, and the direction perpendicular to the slot as the y-direction, and with 1 wavelength λ as the unit, the positions of the 8 receiving antennas are (0.5λ, 5λ), (1.5λ, 5λ), (3λ, 5λ), (4.5λ, 5λ), (5λ, 5λ), (5.5λ, 4.5λ), (5λ, 3.5λ), and (5λ, 0.5λ).

6. The high-isolation plastic metallized waveguide slot antenna according to claim 1, characterized in that, The coaxial probe has a radius of 0.35 mm and a length of 14 mm when inserted into the coaxial waveguide structure (13). The metal probe is located at the center of the wide side of the coaxial waveguide structure (13) and is 7 mm away from the short surface of the coaxial waveguide structure (13).

7. The high-isolation plastic metallized waveguide slot antenna according to claim 1, characterized in that, The height of the transceiver isolation structure is 90mm.

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