An antenna unit based on SIW technology and a high-isolation transceiving antenna array

Abstract

The scheme discloses an antenna unit based on SIW technology and a high-isolation transceiving antenna array, which comprises a dielectric plate, a substrate integrated waveguide and a substrate integrated waveguide slot array; the antenna unit comprises two substrate integrated waveguide slot arrays, and each substrate integrated waveguide slot array is composed of N slot units; the antenna unit adopts a coaxial feeding mode; the N slot units of each substrate integrated waveguide slot array are arranged along the wide side of the substrate integrated waveguide in sequence; and each slot unit is formed by opening a longitudinal slot on the wide side of the substrate integrated waveguide. The scheme designs a unique antenna unit by using the substrate integrated waveguide; the antenna unit is composed of two linear arrays, and each linear array has multiple slot units; the antenna unit adopts a coaxial feeding mode and uses a microstrip line for transition and matching; and each slot unit has a respective offset relative to the center of the waveguide, so that the designed antenna unit meets the design target of low side lobe while meeting the gain and bandwidth.

Description

Technical Field

[0001] This invention belongs to the field of antenna structure technology, and in particular relates to an antenna element and a high-isolation transceiver antenna array based on SIW technology. Background Technology

[0002] Continuous wave radar has received increasing attention in recent years due to its unique performance advantages. Since the receiver and transmitter of a continuous wave radar operate simultaneously, the receiver is also subject to interference from signal leakage from the transmitter while receiving target echoes. This interference severely restricts the detection performance of continuous wave radar; therefore, the isolation between the transmitting and receiving antennas is an extremely important performance indicator for continuous wave radar.

[0003] Coupling between transmitting and receiving antennas includes spatial wave coupling and surface wave coupling. To achieve high isolation between transmitting and receiving antennas in continuous wave radar systems, extensive research has been conducted. For example, Min Li et al. proposed a decoupling method suitable for ultra-short-range MIMO patch antennas in 2020. This method uses a dielectric block (DB) to improve the isolation of the transmitting and receiving antennas by more than 20 dB, reaching -45 dB. However, it still falls short of the requirements for electromagnetic systems with high isolation requirements. You-Feng Cheng et al. improved the isolation of the transmitting and receiving antennas by 19.6 dB by adding a parasitic isolator and a defective ground structure between them. However, this method still lacks sufficient isolation and suffers from severe back lobes, limiting its practicality. Yuting Zhao et al. reduced mutual coupling by 25 dB by adding a defective isolation wall between the transmitting and receiving antennas. While this method improves isolation to some extent, it reduces antenna gain and makes it difficult to achieve planarization and miniaturization of the antenna array.

[0004] All of the above studies have proposed improvements to the transceiver antenna arrays of continuous wave radar in order to increase its isolation. However, there are some unavoidable defects, and it is difficult to obtain a design scheme that can effectively improve the isolation. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing an antenna element and a high-isolation transceiver antenna array based on SIW technology.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions:

[0007] An antenna unit based on SIW technology includes a dielectric substrate, a substrate integrated waveguide implemented on the dielectric substrate, and a substrate integrated waveguide slot array formed by opening longitudinal slots along the wide side of the substrate integrated waveguide.

[0008] The antenna unit includes two substrate integrated waveguide slot arrays, and each substrate integrated waveguide slot array consists of N slot elements. The antenna unit adopts a coaxial feeding method and uses microstrip lines for transition and matching.

[0009] The N slot elements of each substrate integrated waveguide slot array are arranged sequentially along the wide side of the substrate integrated waveguide.

[0010] Each slot cell is formed by creating a longitudinal slot along the wide side of the substrate integrated waveguide.

[0011] In the aforementioned SIW-based antenna unit, the substrate integrated waveguide is implemented by periodically arranged metal pillars on a dielectric substrate, and the substrate integrated waveguide slots are arranged in a linear array on the wide side of the waveguide.

[0012] The width w of the substrate integrated waveguide, the spacing p of the metal pillars, and the diameter d of the metal pillars are determined according to the following formulas (1)-(5):

[0013] (1)

[0014] (2)

[0015] (3)

[0016] (4)

[0017] (5)

[0018] In the above formulas, 'a' represents the width of the equivalent dielectric waveguide; ξ1, ξ2, and ξ3 are intermediate variables.

[0019] In the aforementioned SIW-based antenna unit, the width w of the substrate integrated waveguide is determined to be 6mm-7mm, the spacing p of the metal pillars is determined to be 0.9mm-1mm, and the diameter d of the metal pillars is determined to be 0.45-0.55mm.

[0020] In the aforementioned SIW-based antenna unit, adjacent slot units within each substrate integrated waveguide slot array have the same slot spacing, which is 5mm-7mm.

[0021] The spacing between the two substrate integrated waveguide slot arrays is 6mm-8mm.

[0022] In the aforementioned SIW-based antenna unit, the gap between adjacent slot elements in each substrate integrated waveguide slot array is 5.2 mm.

[0023] The spacing between the two substrate integrated waveguide slot arrays is 7.7 mm.

[0024] In the aforementioned SIW-based antenna unit, each of the N slot elements in the substrate integrated waveguide slot array has its own offset from the center line of the substrate integrated waveguide, and Chebyshev weighting of the slot element cutting current is achieved through these offsets.

[0025] In the aforementioned SIW-based antenna element, each substrate integrated waveguide slot array has 10 slot elements. The 10 slot elements arranged sequentially from the short-circuited end to the feed end of the substrate integrated waveguide are A1, A2, A3, A4, A5, A6, A7, A8, A9, and A10. The offsets of the ten slot elements from the waveguide edge are as follows:

[0026] Slotted unit A 1 A 2 A 3 A 4 A 5 A 6 A 7 A 8 A9 A10 S (mm) 1.5 1.5 2.1 2.2 2.4 2.4 2.2 2.1 1.5 1.5

[0027] A high-isolation transceiver antenna array includes two receiving antennas and one transmitting antenna simultaneously arranged on a dielectric substrate. Both the receiving antenna and the transmitting antenna employ the aforementioned SIW-based antenna element. The two receiving antennas are arranged side-by-side on one side of the dielectric substrate, and the transmitting antenna is positioned on the dielectric substrate such that the pointing of the transmitting antenna and the receiving antenna are located at the null point of their respective radiation patterns.

[0028] In the high-isolation transceiver antenna array described above, the lateral center-to-center distance between the two receiving antennas arranged side by side is 1.5 times the air wavelength.

[0029] In the high isolation transceiver antenna array described above, an electromagnetic bandgap structure is designed between the receiving antenna and the transmitting antenna, covering the operating frequencies of the receiving antenna and the transmitting antenna.

[0030] The advantages of this invention are:

[0031] (1) This scheme uses substrate integrated waveguide to design a unique antenna unit. The antenna unit consists of two linear arrays, and each linear array has multiple slot elements. The antenna unit adopts coaxial feeding and uses microstrip lines for transition and matching. At the same time, each slot element has its own offset relative to the center of the waveguide. This allows the designed antenna unit to achieve the design goal of low sidelobe while meeting the gain and bandwidth requirements, providing a basis for the antenna array to suppress spatial wave coupling.

[0032] (2) Using specially designed antenna elements as the receiving and transmitting antennas of the radar antenna structure can take advantage of the low sidelobe of the antenna array to achieve better space wave suppression from the perspective of the receiving and transmitting antennas themselves.

[0033] (3) By adjusting the relative positions of the transmitting and receiving antennas, spatial wave coupling suppression is effectively achieved by utilizing the null of the antenna pattern without affecting the operation of the radar.

[0034] (4) While achieving high gain, it also achieves low sidelobes in the elevation dimension and wide beam coverage in the azimuth dimension;

[0035] (5) The surface wave coupling of the transmitting and receiving antennas is effectively suppressed by adopting an electromagnetic bandgap (EBG) structure; high isolation is achieved from both the surface wave coupling and space wave coupling perspectives.

[0036] (6) High isolation between the transmitting and receiving antennas is achieved under the premise of small array with common aperture (the distance between the transmitting and receiving antennas is similar to the working wavelength). Such high isolation is achieved for the first time in existing antennas. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the antenna unit structure based on SIW technology of the present invention;

[0038] Figure 2 This is a reflection coefficient diagram of the antenna element based on SIW technology in this invention;

[0039] Figure 3 The radiation pattern of the antenna element based on SIW technology in this invention is shown.

[0040] Figure 4 This is a schematic diagram of the high isolation transceiver antenna array arrangement based on SIW technology of the present invention;

[0041] Figure 5 This invention compares the impact of different relative positions of transceiver antennas on the isolation of transceiver antennas based on SIW technology in a high-isolation transceiver antenna array.

[0042] Figure 6 This is a diagram of the array structure of the high isolation transceiver antenna array based on SIW technology of the present invention after applying the EBG structure;

[0043] Figure 7 The frequency bandgap of the EBG structure used in the high isolation transceiver antenna array of this invention;

[0044] Figure 8 This is a comparison diagram of the isolation of the transmit and receive antennas before and after applying the EBD structure to the high isolation transmit and receive antenna array based on SIW technology of this invention. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0046] This embodiment presents an antenna element and a high-isolation transceiver antenna array based on SIW technology.

[0047] The first designed antenna element is as follows: Figure 1As shown, the substrate material is Rogers RT / Duriod 5880 (… The thickness is 0.508 mm. The substrate integrated waveguide is achieved by periodically arranged metal pillars on a copper-clad dielectric substrate, and an antenna array is formed by opening longitudinal slots along the wide side of the substrate integrated waveguide. Each antenna element consists of two substrate integrated waveguide slot arrays, with each array consisting of 10 slot elements arranged sequentially along the wide side of the substrate integrated waveguide. Specifically, the 10 slot elements of the two substrate integrated waveguide slot arrays are arranged sequentially along the wide side of the substrate integrated waveguide.

[0048] Specifically, in this embodiment, the width W, metal pillar spacing p, and metal pillar diameter d of the substrate integrated waveguide are initially determined according to the following formulas (1)-(5):

[0049] (1)

[0050] (2)

[0051] (3)

[0052] (4)

[0053] (5)

[0054] In this embodiment, considering the ease of processing, the diameter d of the metal column is determined to be 0.5 mm, the distance p between the two metal columns is determined to be 0.95 mm, and the width W of the SIW is determined to be 6.7 mm.

[0055] Furthermore, in this embodiment, the slot spacing is 5.2 mm, the linear array spacing is 7.7 mm, and a coaxial feeding method is adopted, utilizing microstrip lines for transition and matching. Specifically, it is achieved by... Figure 1 The coaxial port is used for power supply, and the microstrip line achieves impedance matching between the coaxial and SIW.

[0056] Figure 1 In the diagram, Фd represents the diameter of the metal pillar, and the corresponding small dots all refer to the metal pillars used to form the substrate integrated waveguide. Slot represents the slot element, and the corresponding racetrack-shaped slot hole refers to the slot element. d_slot represents the slot spacing. MetalColum refers to the metal pillar. Port refers to the coaxial cable used for feeding. P represents the metal pillar spacing. S represents the offset. d_array represents the linear array spacing. W represents the width of the substrate integrated waveguide.

[0057] Furthermore, each of the 10 slot elements in the substrate integrated waveguide slot array has its own offset s from the edge of the substrate integrated waveguide, and these offsets are used to perform Chebyshev weighting on the slot element cutting current. In this embodiment, the 10 slot elements arranged sequentially from the short-circuit end to the feed end of the substrate integrated waveguide are A1, A2, A3, A4, A5, A6, A7, A8, A9, and A10. The offsets of the ten slot elements from the waveguide edge are as follows: The offsets of each slot are shown in Table 1:

[0058] Slotted unit A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 S (mm) 1.5 1.5 2.1 2.2 2.4 2.4 2.2 2.1 1.5 1.5

[0059] The offset from the center is 3.35mm - the offset between the slot element and the waveguide edge.

[0060] The antenna element implemented through the above design has a reflection coefficient as follows: Figure 2 As shown, the frequency band with a reflection coefficient below -10dB is 23.89GHz-24.30GHz, and the high operating frequency provides a basis for the small-aperture design of the antenna array; the radiation pattern of the antenna element is shown in the figure. Figure 3 As shown, the gain is 16.5 dBi, and the elevation sidelobe level is -20.4 dB. It can be seen that the antenna element with the above structure achieves the design goal of low sidelobes while meeting the gain and bandwidth requirements. This is very helpful in suppressing space wave coupling between the transmitting and receiving antennas, and antennas using the above antenna array will have better space wave coupling suppression performance.

[0061] This embodiment further utilizes the antenna elements designed above as the radar's transceiver antennas. The radar's receiving antennas R1 and R2, and transmitting antenna T, all employ the antenna elements designed above. Furthermore, this embodiment uses a 1-transmit, 2-receive array configuration for the radar's transceiver antennas, separating the transmitting and receiving functions of the antenna array, thus making the designed antenna array suitable for continuous wave radar. Specifically, this embodiment designs two receiving antennas and one transmitting antenna on a 120mm*120mm dielectric substrate. The two receiving antennas are located on the same side of the substrate, and the transmitting antenna is located on the other side. The lateral center-to-center distance between the two receiving antennas is 18.75mm (1.5 times the air wavelength). Figure 4 As shown, this forms the radar's transceiver antenna array.

[0062] Based on the above structure, this embodiment further optimizes the antenna array structure by adjusting the position of the transmitting antenna so that the pointing of the transmitting and receiving antennas is located at the null point of their radiation patterns. Simulation verification shows that this relative position has the maximum in-band isolation between the transmitting and receiving antennas. Some experimental data are as follows:

[0063] In this experiment, the longitudinal offset of the transmitting antenna's radiating array is denoted as x, and the lateral offset as y. x ranges from 0 to 50 mm in 10 mm increments, and y ranges from 20 to 70 mm in 10 mm increments. Figure 5 To compare the effect of different relative positions of the transmitting and receiving antennas on the isolation of the transmitting and receiving antennas, it can be seen that when x=50mm and y=30mm, the in-band isolation of the transmitting and receiving antennas is the largest, reaching below -60dB. This relative position is exactly within the range where the pointing of the transmitting and receiving antennas is located at the null point of their respective radiation patterns.

[0064] Furthermore, this embodiment continues to improve the antenna structure, based on the structure determined above, such as... Figure 6 As shown, an EBG electromagnetic bandgap structure is designed between the receiving antenna and the transmitting antenna, and the selected frequency bandgap structure covers the operating frequencies of both the receiving and transmitting antennas. The specific design can be determined by those skilled in the art based on the actual situation. Figure 7 The frequency bandgap of the EBD structure determined in this embodiment.

[0065] This embodiment also performs simulation verification of the transmit and receive antenna isolation before and after using the EBG structure, and obtains... Figure 8 The comparison diagram of transmit and receive isolation shown shows that the addition of the EBG structure can reduce the in-band isolation of the transmit and receive antennas by about 8 dB, which can effectively suppress surface wave coupling.

[0066] This scheme first designs a low-sidelobe, high-gain antenna element. Then, this designed antenna element serves as both the receiving and transmitting antennas, and a one-transmit, two-receive antenna array is designed on a dielectric substrate. This leverages the low sidelobe advantage of the antenna element to achieve better space wave suppression from the perspective of both the receiving and transmitting antennas. Based on this, the antenna array layout is optimized by aligning the pointing directions of the transmitting and receiving antennas with pattern nulls to improve the isolation between them. The effectiveness of this measure is verified through simulation. Finally, an EBG structure is used to further improve the isolation between the transmitting and receiving antennas, simultaneously optimizing both space wave coupling suppression and surface wave coupling suppression, resulting in a final antenna array with high transmitting and receiving antenna isolation.

[0067] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A high isolation transceiving antenna array, characterized by, It includes two receiving antennas and one transmitting antenna arranged on a dielectric substrate, and both the receiving antenna and the transmitting antenna adopt antenna elements based on SIW technology. The two receiving antennas are arranged side by side on one side of the dielectric substrate, and the transmitting antenna is located on the dielectric substrate such that the pointing of the transmitting antenna and the receiving antenna are located at the null point of their respective radiation patterns. The lateral center-to-center distance between the two receiving antennas arranged side by side is 1.5λ, where λ is the wavelength of the center frequency of the antenna's operating frequency band in air; The SIW-based antenna unit includes a dielectric substrate, a substrate integrated waveguide implemented on the dielectric substrate, and a substrate integrated waveguide slot array formed by opening longitudinal slots along the wide side of the substrate integrated waveguide. The antenna unit includes two substrate integrated waveguide slot arrays, and each substrate integrated waveguide slot array consists of N slot elements. The antenna unit adopts a coaxial feeding method and uses microstrip lines for transition and matching. The N slot elements of each substrate integrated waveguide slot array are arranged sequentially along the wide side of the substrate integrated waveguide. Each slot cell is formed by creating a longitudinal slot along the wide side of the substrate integrated waveguide.

2. The high-isolation transceiver antenna array according to claim 1, characterized in that, An electromagnetic bandgap structure is designed between the receiving antenna and the transmitting antenna, covering the operating frequencies of the receiving antenna and the transmitting antenna.

3. The high-isolation transceiver antenna array according to claim 1, characterized in that, The substrate integrated waveguide is achieved by punching periodically arranged metal pillars on a dielectric substrate, and the substrate integrated waveguide slots are arranged in a linear array on the wide side of the waveguide. The width w of the substrate integrated waveguide, the spacing p of the metal pillars, and the diameter d of the metal pillars are determined according to the following formulas (1)-(5): (1) (2) (3) (4) (5) In the above formulas, 'a' represents the width of the equivalent dielectric waveguide; ξ1, ξ2, and ξ3 are intermediate variables.

4. The high-isolation transceiver antenna array according to claim 3, characterized in that, The width w of the substrate integrated waveguide is determined to be 6mm-7mm, the spacing p of the metal pillars is determined to be 0.9mm-1mm, and the diameter d of the metal pillars is determined to be 0.45-0.55mm.

5. The high-isolation transceiver antenna array according to claim 4, characterized in that, Each substrate integrated waveguide slot array has the same slot spacing between adjacent slot elements, and the slot spacing is 5mm-7mm. The spacing between the two substrate integrated waveguide slot arrays is 6mm-8mm.

6. The high-isolation transceiver antenna array according to claim 5, characterized in that, The gap between adjacent slot elements in each substrate integrated waveguide slot array is 5.2 mm; The spacing between the two substrate integrated waveguide slot arrays is 7.7 mm.

7. The high-isolation transceiver antenna array according to any one of claims 1-6, characterized in that, Each of the N slot elements in the substrate integrated waveguide slot array has its own offset from the center line of the substrate integrated waveguide, and Chebyshev weighting of the slot element cutting current is achieved through these offsets.

8. The high-isolation transceiver antenna array according to claim 7, characterized in that, Each substrate integrated waveguide slot array has 10 slot elements. The 10 slot elements arranged sequentially from the short-circuit end to the feed end of the substrate integrated waveguide are A1, A2, A3, A4, A5, A6, A7, A8, A9, and A10. The offsets of the ten slot elements from the waveguide edge are as follows: 。

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