High-gain millimeter wave antenna based on plastic lens

Abstract

The invention provides a plastic lens antenna with a novel structure, which comprises a feed source and a plastic lens for realizing a focusing function, the feed source is arranged at a focal length position below the plastic lens, the plastic lens is prepared by processing Rexolite 1422, the plastic lens structurally comprises a layer of plastic substrate, and a novel lens is arranged at the bottom layer of the plastic substrate. The antenna is simple in structure, low in cost, high in gain and convenient to process and manufacture, and has important potential application value.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology and specifically designs a high-gain millimeter-wave antenna at 24GHz, which can be used in automotive anti-collision radar, security detection, rainfall detection, and 5G communication systems. Background Art

[0002] Against the backdrop of the rapid development of modern information and wireless communications, the use of high-frequency bands such as millimeter waves, submillimeter waves, and terahertz waves is becoming increasingly frequent. Antennas in these frequency bands require very demanding electrical performance parameters, such as wide bandwidth, narrow beam, and high gain.

[0003] Achieving these performance targets is typically achieved through two approaches: feed and lens. The feed is typically achieved through array technology, which involves designing the number of elements, element arrangement, and element excitation coefficients. However, the drawback is that the gain achieved with traditional array technology is already comparable to dielectric loss, conductor loss, and surface wave loss, making it ineffective in improving antenna gain. Furthermore, the antenna size becomes larger. Furthermore, specialized array technologies face challenges such as high design complexity and high costs.

[0004] Lenses apply optical principles to millimeter-wave transmission, focusing the transmitted electromagnetic waves to achieve high performance. Lens designs can be categorized into two types: metasurface lenses and dielectric lenses. Traditional antennas of both types suffer from large size and high cost.

[0005] To address the shortcomings of lenses, plastic lenses have been proposed in recent years, based on dielectric lenses. Plastic lenses are lower-cost dielectric antennas. Compared to traditional dielectric antennas, plastic lenses have a lower dielectric constant and often poorer structural stability. Therefore, material selection is crucial in the highly sensitive millimeter-wave band.

[0006] In industry, polytetrafluoroethylene is usually the material of choice for plastic lenses. However, in recent years, a unique cross-linked polystyrene microwave plastic has been increasingly used in electromagnetic lenses. This material has better physical and electrical properties than polytetrafluoroethylene.

[0007] At the same time, the traditional electromagnetic plastic lens structure design is usually divided into hyperbolic lenses and meniscus lenses. However, these two lenses are subject to large structural constraints and have poor focusing effects. Therefore, based on this, this paper proposes a combined lens to achieve better focusing under structural constraints. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-gain millimeter-wave antenna based on a plastic lens, so as to solve the above-mentioned problems and obtain a high-gain, narrow-beam, low-cost millimeter-wave antenna.

[0009] The technical solution of the present invention is as follows: the high-gain millimeter-wave antenna based on a plastic lens comprises a novel structural plastic lens consisting of a lens obtained by cutting a cylinder from a hemispherical portion of the structure, a hyperbolic lens, and a dielectric plane lens, and a 2×2 parallel-fed patch non-uniform array. The feed source is arranged at a focal length position below the plastic lens, the plastic lens is made of Rexolite 1422, and the structure comprises a plastic substrate, with the novel lens arranged at the bottom of the plastic substrate.

[0010] Preferably, the plastic substrate adopts a 125mm×125mm rectangular structure.

[0011] Preferably, the interior of the novel lens is composed of a hyperbolic lens, the outer surface of which is a plane and the inner surface (illumination surface) is a hyperbolic surface, which satisfies the formula:

[0012] Preferably, the outer portion of the novel lens is obtained by cutting a cylinder from a hemispherical portion of the structure, wherein the hemispherical portion has a radius of 62.5 mm and the cylindrical portion has a radius of 48.8 mm.

[0013] Preferably, the patch array feed is 90 mm from the plastic lens surface and has dimensions of 23.8 mm × 16.8 mm × 0.254 mm. It consists of a top patch, a bottom patch, and a Rogers RO4350 substrate. The top patch is located above the substrate, and the bottom patch is located below the substrate.

[0014] The present invention has the following advantages: (1) Compared with the traditional dielectric delay lens antenna, the present invention has higher gain and narrower beam at 24 GHz. The more penetrating metal acceleration lens antenna is cheaper and smaller in size because it uses plastic material.

[0015] (2) The feed source used in the present invention is a 2×2 parallel-fed patch non-uniform array, which is arranged non-uniformly using a Chebyshev distribution, significantly reducing the sidelobe level and improving the mainlobe directivity. Furthermore, since it is a parallel-fed network, compared to a series-fed array, the excitation path lengths of each unit are similar, resulting in better phase consistency, which is conducive to widening the operating bandwidth. At the same time, the non-uniform array can optimize the overall impedance matching by adjusting the unit size or position, thereby further improving the bandwidth.

[0016] (3) The present invention uses the low-cost Rexolite 1422 material, which has excellent resistance to mechanical damage caused by ionizing radiation, is easy to process, has good rigidity and dimensional stability, is lightweight, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the plastic lens of the present invention; Figure 2 It is a schematic diagram of the overall structure of the present invention; Figure 3 Schematic diagram of a 2×2 parallel-fed patch non-uniform array according to the present invention; Figure 4 is the reflection coefficient diagram of the present invention at 24 GHz; Figure 5 This is the E-plane radiation pattern of the patch array of the present invention when no lens is added.

[0018] Figure 6 This is the H-plane radiation pattern of the patch array of the present invention when no lens is added.

[0019] Figure 7 This is the E-plane radiation pattern of the present invention at 24 GHz.

[0020] Figure 8 This is the H-plane radiation pattern of the present invention at 24 GHz.

[0021] Figure 9 This is the far-field pattern of the present invention at 24 GHz. DETAILED DESCRIPTION

[0022] The present invention will be described in further detail below with reference to the accompanying drawings.

[0023] Example like Figure 1 The present invention discloses an omnidirectional, high-gain millimeter-wave antenna based on a plastic lens. The antenna comprises a feed source (an array patch antenna) and a plastic lens that increases gain and reduces beamwidth. The feed source is positioned beneath the plastic lens, which is made of Rexolite 1422 and comprises a plastic substrate with a novel lens positioned underneath.

[0024] like Figure 2 As shown, this is a new lens structure. The top layer is a plastic substrate. In this embodiment, the length and width are taken as but not limited to 125 mm. The interior is composed of a hyperbolic lens. The outer surface is a plane, and the inner surface (illumination surface) is a hyperbolic surface, which satisfies the formula:

[0025] After the surface of the millimeter wave dielectric lens is determined, its thickness d needs to be determined, which is actually to determine the radiation aperture D. For the hyperbolic lens used in this embodiment, the ratio of its thickness d to its diameter D satisfies the following formula:

[0026] The focal diameter ratio f / D=0.9-1.6. In this embodiment, f is adopted but not limited to 90 mm, that is, the diameter of the hyperbolic lens is determined to be 100 mm.

[0027] The outer part is cut by a hemispherical part structure from a cylinder, the radius of the hemispherical part is 62.5mm, and the radius of the cylinder is 48.8mm. The purpose is to increase the maximum illumination half-angle of the radiation feed source under the condition of the focal length ratio being determined, so as to obtain greater gain.

[0028] As shown in Figure 3 , an array patch antenna is used as a feed source in the embodiment, but is not limited to this. The feed source is a 2x2 non-uniform array of parallel-fed patches arranged non-uniformly by Chebyshev distribution. In order to make the lens antenna achieve high efficiency, the feed source should have the characteristics of rotationally symmetrical radiation pattern, low cross-polarization component, and good beam equalization in a wide frequency band. The aperture antenna of the horn type can well meet these characteristics, but it has a large volume and weight, and the processing is complex. Although the microstrip patch antenna has the advantages of flexible polarization mode, simple manufacturing process, light weight, and easy integration, etc., the performance of the rotationally symmetrical pattern, equalization, and cross-polarization is poorer than that of the former. The size of the microstrip patch antenna is 23.8mmx16.8mmx0.254mm. The microstrip patch antenna is composed of a top patch, a bottom patch, and a Rogers RO4350 substrate. The top patch is located above the substrate, and the bottom patch is located below the substrate. As shown in Figure 4 , the working frequency is 24GHz.

[0029] The simulation results of the present application are further described below in combination with the drawings: Simulation 1: CST is used to solve the E-plane and H-plane radiation patterns of the patch array of the present application at 24GHz frequency without adding a lens, and the results are shown in Figure 5 , Figure 6 . As can be seen from Figure 5 , Figure 6 , the half-power beamwidth of the E-plane pattern of the lens antenna at this frequency is 41.7°, the half-power beamwidth of the H-plane pattern is 46.1°, and the maximum gain is 12.5dB.

[0030] Simulation 2: CST is used to solve the E-plane and H-plane radiation patterns of the present application at 24GHz frequency, and the results are shown in Figure 7 , Figure 8 . As can be seen from Figure 7 , Figure 8 , after adding the lens, the half-power beamwidth of the E-plane pattern of the present application at this frequency is 8°, the half-power beamwidth of the H-plane pattern is 6.8°, and the maximum gain is 24.4dB. It can be seen that the beamwidth is greatly reduced, but the beamforming effect in the H-plane is better. Figure 9 The overall far-field pattern is shown in

[0031] Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations are described above, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0032] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A high-gain millimeter-wave antenna based on a plastic lens, characterized in that: The feed source is positioned at the focal length below the plastic lens. The plastic lens is made of Rexolite 1422 and comprises a plastic substrate with a novel lens disposed underneath. The invention has a simple structure, low cost, high gain, and is easy to manufacture, thus possessing significant potential applications.

2. The high-gain millimeter-wave plastic lens antenna according to claim 1, characterized in that: The plastic substrate adopts a 125mm×125mm rectangular structure.

3. The high-gain millimeter-wave plastic lens antenna according to claim 1, characterized in that: The interior of the new lens is composed of a hyperbolic lens, whose outer surface is a plane and the inner surface (illumination surface) is a hyperbolic surface, which satisfies the formula: 。 4. The high-gain millimeter-wave plastic lens antenna according to claim 1, characterized in that: The exterior of the new lens is made by cutting a cylinder from a hemispherical part of the structure. The hemispherical part has a radius of 62.5 mm and the cylindrical part has a radius of 48.8 mm.

5. A high-gain millimeter-wave plastic lens antenna according to claims 2, 3, and 4, characterized in that: The plastic material used is Rexolite 1422, which has a dielectric constant of 2.53 and an extremely low dissipation factor.

6. The high-gain millimeter-wave plastic lens antenna according to claim 1, characterized in that: The distance between the patch array feed source and the plastic lens surface is 90 mm, and the size is 23.8 mm × 16.8 mm × 0.254 mm. It consists of a top patch, a bottom patch and a Rogers RO4350 substrate. The top patch is located above the substrate, and the bottom patch is located below the substrate.

7. The high-gain millimeter-wave plastic lens antenna according to claim 6, characterized in that: The top patch is a non-uniform array of 2×2 rectangular metal patches, connected to the input through a Chebyshev impedance transformer and a microstrip line. The bottom patch is a rectangular metal patch that fully covers the bottom of the substrate.

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