A structure for suppressing multiple reflections of radar internal beams and a design method thereof

Abstract

The application discloses a structure for suppressing multiple reflections of radar internal beams, comprising at least one set of rectangular patch groups, which are arranged in three rows and three columns on an antenna board; the design method comprises the following steps: determining the in-phase reflection phase band gap position of the rectangular patch group structure according to a preset RCS frequency band; designing the initial size of the rectangular patch group structure according to an equivalent LC resonant circuit formula of the rectangular patch group structure and the geometric size of the antenna; ensuring that at least three complete rectangular patch groups are used; and optimizing the calculation of the in-phase reflection phase band gap of the rectangular patch group structure until the band gap completely covers the RCS reduction frequency band of the antenna. The application reduces the multiple reflections of the radar internal beams through the design of the rectangular patch group structure, and improves the signal-to-noise ratio of the radar; the rectangular patch group structure is simple and easy to process, and the problems of complex process and high cost caused by the grounding hole processing are overcome.

Description

Technical Field

[0001] This application relates to the field of array antenna technology, and in particular to a structure and design method for suppressing multiple reflections of the internal beam of a radar. Background Technology

[0002] In microstrip antennas, surface waves typically propagate at the interface between the dielectric substrate and air. Radar antenna substrates are usually installed inside the radar. Due to the presence of the radome, electromagnetic waves emitted by the antenna undergo multiple reflections within the radome. A significant portion of these reflections reach both the receiving and transmitting antennas, leading to a decrease in the overall radar signal-to-noise ratio and reduced detection performance. Therefore, it is crucial to minimize mutual coupling between the transmitting and receiving antennas and maximize their isolation to ensure stable radar operation.

[0003] Existing technical solutions commonly involve connecting a metal patch to a metal ground plane via a vertical conductive hole. This metal patch is typically rectangular, hexagonal, or triangular. However, this method requires the fabrication of grounding holes, which is complex and costly. Summary of the Invention

[0004] Based on the above problems, this application provides a structure and design method for suppressing multiple reflections of the radar internal beam. By using an irregular arrangement of three rows and three columns of patch units, the reflection of the microwave beam inside the radar is reduced, thus solving the problems of high radar signal-to-noise ratio and complex manufacturing process.

[0005] First, the present invention provides a structure for suppressing multiple reflections of the internal beam of a radar, including at least one set of rectangular patch groups, which are arranged in three rows and three columns on an antenna plate. The antenna plate is also provided with at least one transmitting antenna module and at least one receiving antenna module.

[0006] At least one set of rectangular patch groups is provided between the transmitting antenna modules and between the receiving antenna modules;

[0007] The edge of the transmitting antenna module or the receiving antenna module is provided with at least one set of rectangular patches.

[0008] Optionally, the rectangular patch group includes 9 sub-pattern units, each of which is a rectangle with different lengths and widths, and an aspect ratio of 5:4; the sub-pattern units are electromagnetic wave absorbing sheets.

[0009] Optionally, the arrangement of the rectangular patch group includes a forward arrangement and a horizontal arrangement.

[0010] Optionally, adjacent rectangular patch groups may be arranged in different ways.

[0011] Optionally, the rectangular patch group is an electromagnetic bandgap structure.

[0012] Optionally, the transmitting antenna module includes three modules, specifically a first transmitting antenna module, a second transmitting antenna module, and a third transmitting antenna module;

[0013] Optionally, the receiving antenna module includes four modules, specifically a first receiving antenna module, a second receiving antenna module, a third receiving antenna module, and a fourth receiving antenna module.

[0014] Optionally, the transmitting antenna module and the receiving antenna module are connected to the central MMIC chip.

[0015] Optionally, one side of the second transmitting antenna module is adjacent to the first transmitting antenna module, and the other side is adjacent to the third transmitting antenna module; a three-row, two-column rectangular patch group is provided between the first transmitting antenna module and the second transmitting antenna module, and between the second transmitting antenna module and the third transmitting antenna module; a five-row, two-column rectangular patch group is provided on the other side of the first transmitting antenna module and the other side of the third transmitting antenna module.

[0016] Optionally, a four-row-one-column rectangular patch group is provided between the second receiving antenna module and the third receiving antenna module; the first receiving antenna module has two columns of rectangular patch groups on its first side, wherein the first column has ten rows and the second column has four rows; the first receiving antenna module has two rows of two columns of rectangular patch groups on its second side; and the first receiving antenna module has four rows of one column of rectangular patch groups on its third side.

[0017] Optionally, the fourth receiving antenna module is arranged in a mirror image of the rectangular patch group surrounding the first receiving antenna module.

[0018] Optionally, the antenna plate has a first layer as a reflection suppression layer, a second layer as a dielectric layer, and a third layer as a ground plane layer. This ground plane is shared with the receiving and transmitting antennas. By designing the appropriate size and position, the principle of zero superposition of the incoming and outgoing phases is achieved, thereby reducing electromagnetic wave reflection and minimizing radar cross section (RCS).

[0019] Secondly, this invention provides a structural design method for suppressing multiple reflections of the radar beam, comprising the following steps:

[0020] Step 1: Determine the position of the in-phase reflection phase bandgap of the rectangular patch group structure according to the preset RCS frequency band, and the bandgap range covers its RCS reduction frequency band;

[0021] Step 2: Based on the equivalent LC resonant circuit formula of the rectangular patch group structure, and based on the physical and geometric dimensions of the antenna, design the initial dimensions of the rectangular patch group structure to ensure that at least three complete rectangular patch groups are used. Only then will the rectangular patch group structure have relatively stable in-phase reflection phase characteristics.

[0022] H = 0.8W

[0023] In the formula, W represents the width of the electromagnetic wave absorbing sheet, and H represents the height of the electromagnetic wave absorbing sheet.

[0024]

[0025] L=μ0t

[0026] Where ε₀ is the vacuum permittivity; ε r U is the relative permittivity of the dielectric; μ0 is the permeability of free space; the resonant frequency and bandgap width of the equivalent LC parallel resonant circuit of the rectangular patch group can be expressed as:

[0027]

[0028] g is the width of the first gap between the electromagnetic wave absorbing plates, and a is the translation period of each group of electromagnetic wave absorbing plates, i.e., a = W + g.

[0029] Step 3: Simulate the model of the infinite periodic unit based on the Floquet port method, and verify and optimize the in-phase reflection phase bandgap of the rectangular patch group structure using high-frequency electromagnetic simulation software;

[0030] Step 4: If the bandgap completely covers the antenna RCS reduction band, the design is complete; otherwise, adjust the unit size reasonably according to the influence of each parameter of the rectangular patch group structure on the bandgap, and repeat steps 2 and 3.

[0031] Compared with the prior art, this application has the following beneficial effects:

[0032] This application reduces multiple reflections of the radar's internal beam by designing a rectangular patch group structure, thereby improving the radar's signal-to-noise ratio.

[0033] The rectangular patch assembly structure of this application is simple and easy to manufacture, overcoming the complex process and high cost problems caused by the processing of grounding holes.

[0034] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the PCB of the MIMO radar of the present invention, which transmits and receives multiple signals simultaneously.

[0037] Figure 2 This is a schematic diagram of the rectangular patch assembly structure of the present invention;

[0038] Figure 3 This is a schematic diagram showing the locations of the anti-reflection layer, dielectric layer, and ground plane layer of the MIMO radar of the present invention.

[0039] Figure 4 This is a schematic diagram showing the distribution of the rectangular patch group around the first receiving antenna module of the present invention;

[0040] Figure 5 This invention relates to a structural design method for suppressing multiple reflections of the radar's internal beam.

[0041] In the diagram: T1, first transmitting antenna module; T2, second transmitting antenna module; T3, third transmitting antenna module; R1, first receiving antenna module; R2, second receiving antenna module; R3, third receiving antenna module; R4, fourth receiving antenna module;

[0042] 1. Rectangular patch group; 11. Width of electromagnetic wave absorbing sheet; 12. Height of electromagnetic wave absorbing sheet; 2. Anti-reflection layer; 3. Dielectric layer; 4. Ground plane layer; 51. First side of first receiving antenna module; 52. Second side of first receiving antenna module; 53. Third side of first receiving antenna module. Detailed Implementation

[0043] As described earlier, during the process of transmitting electromagnetic waves, a certain amount of electromagnetic waves will be reflected multiple times inside the radome. A large portion of these reflections will reach the receiving and transmitting antennas, which will reduce the overall radar signal-to-noise ratio and reduce radar detection performance. Furthermore, electromagnetic bandgap structures often require the fabrication of grounding holes, resulting in high manufacturing costs.

[0044] To better illustrate the embodiments of this application, the terms used in the embodiments of this application will first be explained.

[0045] Array antenna: An antenna system composed of many identical individual antennas (such as symmetrical antennas) arranged in a certain pattern is also called an antenna array. The independent units that make up an antenna array are called array elements or antenna elements. If the array elements are arranged in a straight line or a plane, it is called a linear array or a planar array.

[0046] Electromagnetic bandgap structure: An electromagnetic bandgap structure (EBG) is an artificial periodic structure. It possesses bandgap characteristics and reflection phase characteristics.

[0047] MMIC: MMIC is an abbreviation for monolithic microwave integrated circuit. It is a series of semiconductor processes used to manufacture passive and active components on a semi-insulating semiconductor substrate and connect them to form a functional circuit for use in the microwave (or even millimeter wave) frequency band.

[0048] MIMO radar consists of multiple reflector antennas and multiple receiver antennas, which can share both transmitting and receiving capabilities. Each reflector antenna reflects a different signal waveform, and each reflected signal is received by multiple receiver antennas after being reflected by the target. The signal is then processed by a multiplexer and output for further processing.

[0049] Radar antenna panels are typically installed inside the radar. Due to the presence of the radar radome, some electromagnetic waves will inevitably be reflected multiple times inside the radome during the transmission of electromagnetic waves. A large portion of these reflections will reach the receiving and transmitting antennas, which will reduce the overall signal-to-noise ratio of the radar and decrease its detection performance. Therefore, it is necessary to minimize reflections inside the radar to ensure stable operation.

[0050] Existing technical solutions commonly involve connecting a metal patch to a metal ground plane via a vertical conductive hole. This metal patch is typically rectangular, hexagonal, or triangular. However, this method requires the fabrication of grounding holes, which is complex and costly.

[0051] In view of this, the structure for suppressing multiple reflections of the radar internal beam provided in this application reduces multiple reflections of the radar internal beam through the design of a rectangular patch group structure. Furthermore, the rectangular patch group structure between antennas increases the isolation between receiving antennas, transmitting antennas, and transmitting and receiving antennas, thereby improving the radar's signal-to-noise ratio. Small rectangular patch groups are designed on the surface of the first layer of the PCB, arranged in three rows and three columns as a group, with each group staggered around the transmitting and receiving antennas. The second layer is a dielectric layer, and the third layer is a complete ground plane. This ground plane shares the ground with the receiving and transmitting antennas. By designing appropriate dimensions and positions, the principle of zero superposition of the incoming and outgoing phases is achieved, thereby reducing electromagnetic wave reflection and minimizing the radar cross section (RCS).

[0052] The rectangular patch group of this application has a simple structure and is easy to implement, overcoming the problems of complex process and high cost caused by the processing of grounding holes.

[0053] The following section, with reference to the accompanying drawings, provides a detailed and complete description of the structural design method for suppressing multiple reflections of the radar's internal beam.

[0054] See Figure 1 The figure is a schematic diagram of a MIMO radar PCB provided in an embodiment of this application. The present invention provides a structure for suppressing multiple reflections of the internal beam of a radar, including 80 rectangular patch groups 1. The rectangular patch groups 1 are arranged in three rows and three columns as a group and are disposed on an antenna board. The antenna board is also provided with a transmitting antenna module and a receiving antenna module.

[0055] In one possible implementation, the transmitting antenna module includes three modules: a first transmitting antenna module, a second transmitting antenna module, and a third transmitting antenna module; one side of the second transmitting antenna module is adjacent to the first transmitting antenna module, and the other side is adjacent to the third transmitting antenna module.

[0056] There are three rows and two columns of rectangular patch groups 1 between the first transmitting antenna module and the second transmitting antenna module, and between the second transmitting antenna module and the third transmitting antenna module; there are five rows and two columns of rectangular patch groups 1 on the other side of the first transmitting antenna module and the other side of the third transmitting antenna module.

[0057] In one possible implementation, the receiving antenna module includes four modules, specifically a first receiving antenna module, a second receiving antenna module, a third receiving antenna module, and a fourth receiving antenna module.

[0058] like Figure 4 As shown, there are four rows and one column of rectangular patch groups 1 between the second receiving antenna module and the third receiving antenna module; the first side 51 of the first receiving antenna module has two columns of rectangular patch groups 1, of which the first column has ten rows and the second column has four rows, for a total of 14 rectangular patch groups 1; the second side 52 of the first receiving antenna module has two rows and two columns, for a total of 4 rectangular patch groups 1; and the third side 53 of the first receiving antenna module has four rows and one column, for a total of 4 rectangular patch groups 1.

[0059] In one possible implementation, the fourth receiving antenna module is arranged in a mirror image of the rectangular patch group 1 surrounding the first receiving antenna module.

[0060] In one possible implementation, the rectangular patch group 1 includes 9 sub-pattern units, each of which is a rectangle with different lengths and widths, and an aspect ratio of 5:4; the sub-pattern units are electromagnetic wave absorbing sheets.

[0061] As one possible implementation, the rectangular patch group 1 can be arranged in a forward orientation or a horizontal orientation.

[0062] As one possible implementation method, such as Figure 2 As shown, the adjacent rectangular patch groups 1 are arranged in different ways.

[0063] As one possible implementation, the rectangular patch group 1 is an electromagnetic bandgap structure.

[0064] In one possible implementation, the transmitting antenna module and the receiving antenna module are connected to a central MMIC chip.

[0065] As one possible implementation method, such as Figure 3 As shown, the first layer of the antenna plate is the anti-reflection layer 2, the second layer is the dielectric layer 3, and the third layer is the ground plane layer 4. This ground plane is shared with the receiving and transmitting antenna. By designing the appropriate size and position, the principle of zero superposition of the incoming and outgoing phases is achieved, thereby reducing the reflection of electromagnetic waves and minimizing the radar cross section (RCS).

[0066] An MMIC chip is installed at the center of the PCB, which is connected to the transmitting antenna (T1 / T2 / T3) and the receiving antenna (R1 / R2 / R3). A rectangular patch array is arranged around the antenna printed circuit board (PCB) to reduce the coupling between antennas, reduce the isolation between transmitting antennas and between receiving antennas, and reduce the reflection of electromagnetic waves at the edges.

[0067] Secondly, such as Figure 5 As shown, this embodiment also provides a structural design method for suppressing multiple reflections of the radar internal beam, including the following steps:

[0068] Step 1: Determine the position of the in-phase reflection phase bandgap of the rectangular patch group structure according to the preset RCS frequency band, and the bandgap range covers its RCS reduction frequency band;

[0069] Step 2: Based on the equivalent LC resonant circuit formula of the rectangular patch group structure, and based on the physical and geometric dimensions of the antenna, design the initial dimensions of the rectangular patch group structure to ensure that at least three complete rectangular patch groups are used. Only then will the rectangular patch group structure have relatively stable in-phase reflection phase characteristics.

[0070] H = 0.8W

[0071] In the formula, W represents the width of the electromagnetic wave absorbing sheet (12), and H represents the height of the electromagnetic wave absorbing sheet (11).

[0072]

[0073] L=μ0t

[0074] Where ε₀ is the vacuum permittivity; ε r U is the relative permittivity of the dielectric; μ0 is the permeability of free space; the resonant frequency and bandgap width of the equivalent LC parallel resonant circuit of the rectangular patch group can be expressed as:

[0075]

[0076] g is the width of the first gap between the electromagnetic wave absorbing plates, and a is the translation period of each group of electromagnetic wave absorbing plates, i.e., a = W + g.

[0077] Step 3: Simulate the model of the infinite periodic unit based on the Floquet port method, and verify and optimize the in-phase reflection phase bandgap of the rectangular patch group structure using high-frequency electromagnetic simulation software;

[0078] Step 4: If the bandgap completely covers the antenna RCS reduction band, the design is complete; otherwise, adjust the unit size reasonably according to the influence of each parameter of the rectangular patch group structure on the bandgap, and repeat steps 2 and 3.

[0079] While several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this application. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0080] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A structure for suppressing multiple reflections of an internal beam of a radar, characterized by, The antenna comprises at least one group of rectangular patch groups arranged in three rows and three columns on an antenna board, and at least one transmitting antenna module and at least one receiving antenna module are arranged on the antenna board. At least one group of the rectangular patch groups is arranged between the transmitting antenna modules and between the receiving antenna modules. At least one group of the rectangular patch groups is arranged on the edge of the transmitting antenna module or the receiving antenna module. Each of the rectangular patch groups comprises nine sub-patch units, each of which is a rectangle with unequal length and width and a length-width ratio of 5:4, and each of the sub-patch units is an electromagnetic wave absorption sheet. The arrangement of the rectangular patch groups comprises forward arrangement and transverse arrangement, and the arrangement modes of adjacent rectangular patch groups are different. The rectangular patch groups are electromagnetic bandgap structures.

2. The structure for suppressing multiple reflections of an internal beam of a radar according to claim 1, characterized by, The transmitting antenna module comprises three modules, specifically a first transmitting antenna module, a second transmitting antenna module and a third transmitting antenna module. The receiving antenna module comprises four modules, specifically a first receiving antenna module, a second receiving antenna module, a third receiving antenna module and a fourth receiving antenna module. The transmitting antenna module and the receiving antenna module are connected to a central MMIC chip.

3. The structure for suppressing multiple reflections of an internal beam of a radar according to claim 2, characterized by, One side of the second transmitting antenna module is adjacent to the first transmitting antenna module, and the other side is adjacent to the third transmitting antenna module; three rows and two columns of rectangular patch groups are arranged between the first transmitting antenna module and the second transmitting antenna module and between the second transmitting antenna module and the third transmitting antenna module; and five rows and two columns of rectangular patch groups are arranged on the other side of the first transmitting antenna module and the other side of the third transmitting antenna module.

4. The structure for suppressing multiple reflections of an internal beam of a radar according to claim 2, characterized by, Four rows and one column of rectangular patch groups are arranged between the second receiving antenna module and the third receiving antenna module; two columns of rectangular patch groups are arranged on the first side of the first receiving antenna module, in which the first column comprises ten rows and the second column comprises four rows; two rows and two columns of rectangular patch groups are arranged on the second side of the first receiving antenna module; and four rows and one column of rectangular patch groups are arranged on the third side of the first receiving antenna module. The arrangement of the rectangular patch groups around the fourth receiving antenna module is the same as that around the first receiving antenna module.

5. The structure for suppressing multiple reflections of internal beams of a radar according to claim 1, characterized by, The first layer of the antenna board is a reflection suppression layer, the second layer is a dielectric layer, and the third layer is a ground plane layer, which is co-located with the receiving and transmitting antennas.

6. The method of designing a structure to suppress multiple reflections of an internal radar beam according to claim 1, wherein, The method comprises the following steps: Step 1: determining the in-phase reflection phase bandgap position of the rectangular patch group structure according to a preset RCS frequency band, and covering the RCS reduction frequency band of the bandgap range; Step 2: designing the initial size of the rectangular patch group structure based on the equivalent LC resonant circuit formula of the rectangular patch group structure and the physical and geometric dimensions of the antenna, and ensuring that at least three complete rectangular patch groups are used, so that the rectangular patch group structure has relatively stable in-phase reflection phase characteristics; ； In the formula, represents the width of the electromagnetic wave absorbing sheet, represents the height of the electromagnetic wave absorbing sheet; Step 3: simulating the model of an infinite periodic unit based on the Floquet port method, and optimizing the calculation of the in-phase reflection phase bandgap of the rectangular patch group structure; Step 4: if the bandgap completely covers the RCS reduction frequency band of the antenna, the design is completed; otherwise, the unit size is adjusted according to the influence of the rectangular patch group structure parameters on the bandgap, and steps 2 and 3 are repeated.

Images