A sandwiched dragon-bow lens antenna with independent adjustment capability of double-frequency radiation characteristics

Abstract

The application discloses a sandwiched dragon-burn lens antenna with independent adjustment ability of double-frequency radiation characteristics, which comprises a first planar dragon-burn lens, a second planar dragon-burn lens and a third planar dragon-burn lens, the first planar dragon-burn lens is located on the upside of the second planar dragon-burn lens, the third planar dragon-burn lens is located on the downside of the second planar dragon-burn lens, the structure of the first planar dragon-burn lens is the same as that of the third planar dragon-burn lens, and the structure of the first planar dragon-burn lens is different from that of the second planar dragon-burn lens. The application has double-frequency radiation characteristics and independent adjustment ability of double-frequency bands by using two planar dragon-burn lenses with different structures, and the heterogeneous design is beneficial to realizing structure simplification, effectively reducing design and processing difficulty and reducing the influence caused by size errors due to manufacturing tolerances. The application is widely applied in the technical field of antennas.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics. Background Technology

[0002] With the rapid development of wireless communication technology, dual-band communication is playing an increasingly important role in future communication systems. The lower operating frequency band offers good coverage, while the higher frequency band provides broadband, high-speed, and low-latency communication services. To reduce the impact of propagation path loss and improve signal coverage flexibility, antennas capable of achieving high gain and wide-angle scanning multi-beam radiation characteristics across both frequency bands are becoming the ideal choice for future communication equipment.

[0003] Current dual-band antennas generally suffer from drawbacks such as relatively low frequencies in both bands and a lack of independent adjustment capability for dual-band radiation characteristics. Specifically, the lower frequency bands are unfavorable for high-speed communication, and the inability to independently adjust the dual-band radiation characteristics limits the flexibility of use. Summary of the Invention

[0004] In view of the technical problems of current dual-band antennas, such as the relatively low frequencies of both bands and the lack of independent adjustment capability of dual-band radiation characteristics, the purpose of this invention is to provide a sandwich Luneburg lens antenna with independent adjustment capability of dual-band radiation characteristics.

[0005] This invention includes a sandwich Luneburg lens antenna with independent adjustment capability for dual-frequency radiation characteristics. The sandwich Luneburg lens antenna with independent adjustment capability for dual-frequency radiation characteristics includes:

[0006] A first-plane Luneburg lens, a second-plane Luneburg lens, and a third-plane Luneburg lens; the first-plane Luneburg lens is located above the second-plane Luneburg lens, and the third-plane Luneburg lens is located below the second-plane Luneburg lens. The structure of the first-plane Luneburg lens is the same as that of the third-plane Luneburg lens, but different from that of the second-plane Luneburg lens.

[0007] Furthermore, both the first planar Luneburg lens and the third planar Luneburg lens are of the woodpile structure;

[0008] The second planar Luneburg lens comprises multiple cubic structural units;

[0009] The edges of the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens are respectively provided with dielectric protrusion fixing structures, and the dielectric protrusion fixing structures are provided with through holes;

[0010] The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics also includes nylon screws, nylon nuts, and nylon washers; the nylon washers are placed between two corresponding dielectric protrusion fixing structures, the nylon screws pass through the through holes of the dielectric protrusion fixing structures and the nylon washers, and the nylon nuts fix the nylon screws.

[0011] Furthermore, the first planar Luneburg lens and the third planar Luneburg lens each include a plurality of dielectric rods with rectangular cross sections, each dielectric rod being located in a corresponding layer, and the dielectric rods in each layer being stacked.

[0012] The dielectric rods in the same layer are parallel to each other and arranged periodically in a horizontal cycle;

[0013] The dielectric rod in any layer is spatially perpendicular to the dielectric rod in the adjacent layer;

[0014] Each of the dielectric rods in any layer is offset relative to each of the dielectric rods in the layer between them by half a horizontal period.

[0015] Furthermore, the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens are all disk-shaped; the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens have the same radius and their centers are aligned.

[0016] The cubic structural units in the second planar Luneburg lens are arranged in a multi-layered ring around the center of the disk.

[0017] Furthermore, each of the dielectric rods located in the inner cylindrical region has a first dimensional parameter, and each of the dielectric rods located in the outer annular region has a second dimensional parameter;

[0018] Each of the cubic structural units located in the inner cylindrical region is solid, and each of the cubic structural units located in the outer annular region is provided with a cylindrical air hole, which is perpendicular to the plane where the second plane Luneburg lens is located.

[0019] The inner cylindrical region is the spatial region extending outward from the center axis of the cylinder formed by the stacking of the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens. The outer annular region is the spatial region in the cylinder other than the inner cylindrical region.

[0020] Furthermore, the sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics also includes:

[0021] Multiple dual-frequency feed antennas; each of the dual-frequency feed antennas is distributed on the edge of the second planar Luneburg lens and is mechanically connected to the second planar Luneburg lens.

[0022] Furthermore, the dual-frequency feed antenna includes a patch antenna and a metal open waveguide antenna; the operating frequency of the metal open waveguide antenna is located in a first frequency band, and the operating frequency of the patch antenna is located in a second frequency band, wherein the first frequency band is higher than the second frequency band;

[0023] The patch antenna has an opening;

[0024] The metal open waveguide antenna passes through the opening of the patch antenna, thereby being nested within the patch antenna.

[0025] Furthermore, the edge of the second planar Luneburg lens is provided with multiple slots; the shape and size of the slots match one end of the metal open waveguide antenna;

[0026] One end of the metal open waveguide antenna is an opening, and the other end is a metal short-circuit wall;

[0027] The opening end of the metal open waveguide antenna is embedded in the slot, thereby forming a mechanical connection with the second planar Luneburg lens;

[0028] The other end of the metal open waveguide antenna is fitted with a first SMA connector.

[0029] Furthermore, the metal open waveguide antenna has a pair of trapezoidal metal ridges inside;

[0030] The longer base of the trapezoidal metal ridge faces outward from the metal open waveguide antenna, and the sloping waist of the trapezoidal metal ridge extends from the opening of the metal open waveguide antenna into the interior of the metal open waveguide antenna; the right-angle waist of the trapezoidal metal ridge is connected to the metal short-circuit wall of the metal open waveguide antenna; the upper part of the right-angle waist of the trapezoidal metal ridge has two stepped grooves.

[0031] The shorter bases of the two trapezoidal metal ridges are opposite each other;

[0032] One of the trapezoidal metal ridges has a through hole perpendicular to the bottom edge. The inner conductor of the first SMA connector passes through the through hole of the trapezoidal metal ridge and forms an electrical contact with the other trapezoidal metal ridge. The outer conductor of the first SMA connector is connected to the outside of the metal open waveguide antenna.

[0033] Furthermore, the patch antenna includes a substrate, a metal patch, a metal ground, and a second SMA connector;

[0034] The metal patch is disposed on one side of the substrate, and the metal ground is disposed on the other side of the substrate;

[0035] The inner conductor of the second SMA connector is in electrical contact with the metal patch, and the outer conductor of the second SMA connector is in electrical contact with the metal ground.

[0036] The beneficial effects of the present invention are: the sandwich Luneburg lens antenna in the embodiment has dual-frequency radiation characteristics and independent adjustment capability for dual frequency bands by using two planar Luneburg lenses with different structures. This heterogeneous design is conducive to simplifying the structure, effectively reducing the difficulty of design and processing, and reducing the impact of dimensional errors caused by manufacturing tolerances. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the sandwich Luneburg lens antenna in the embodiment;

[0038] Figure 2 This is a schematic diagram of the structure of the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens in the embodiment;

[0039] Figure 3 This is a schematic diagram of the woodpile structure formed by the medium rods in the embodiment;

[0040] Figure 4 This is a schematic diagram of the cubic structural unit in the embodiment;

[0041] Figure 5 This is a schematic diagram of the inner cylindrical region and the outer annular region in the embodiment;

[0042] Figure 6 This is a schematic diagram showing the installation position of the dual-frequency feed antenna in the embodiment;

[0043] Figure 7 This is a schematic diagram of the dual-frequency feed antenna in the embodiment;

[0044] Figure 8 This is a schematic diagram of the patch antenna and the metal open waveguide antenna in the embodiment;

[0045] Figure 9 This is a schematic diagram comparing the propagation of electromagnetic waves of different frequencies inside the sandwich Luneburg lens antenna in this embodiment with that inside an existing broadband metamaterial planar Luneburg lens.

[0046] Figure 10 This is a schematic diagram illustrating the simulation and measured results of the return loss-operating frequency of the sandwich Luneburg lens antenna in this embodiment.

[0047] Figure 11 This is a schematic diagram showing the isolation coefficients between the ports of the sandwich Luneburg lens antenna in this embodiment;

[0048] Figure 12The radiation pattern of ports 6-10 of the sandwich Luneburg lens antenna in this embodiment in the XoY plane when the operating frequency is 5.8GHz;

[0049] Figure 13 and Figure 14 This is a schematic diagram showing the measured results and simulation data of the stable high-gain multi-beam radiation generated by the sandwich Luneburg lens antenna in this embodiment at 24GHz and 27GHz.

[0050] Figure 15 and Figure 16 This is a schematic diagram illustrating the ability of the sandwich Luneburg lens antenna in this embodiment to independently adjust its dual-frequency radiation characteristics.

[0051] Figure 17 The above are electric field distribution diagrams on the XoZ plane at different frequencies obtained from the simulation of the sandwich Luneburg lens antenna in this embodiment.

[0052] Figure 18 This is a schematic diagram showing the gain-frequency relationship of all ports of the sandwich Luneburg lens antenna in this embodiment. Detailed Implementation

[0053] Luneburg lens antennas have the following important properties: 1. They can generate high-gain narrow radiation beams; 2. They can generate multiple nearly uniform radiation beams, and wide-angle multi-beam scanning can be achieved by switching the excitation of the feed antenna; 3. They do not require complex feeding and phase-shifting networks to achieve wide-angle beam scanning.

[0054] Dual-band Luneburg lens antennas can be constructed from multiple layers of homogeneous dielectric material or broadband metamaterial structures covering two operating frequency bands. Using homogeneous dielectric materials is limited by the inherent properties of the material itself, making it difficult to meet design requirements. Dual-band Luneburg lenses based on broadband metamaterial structures have two drawbacks: 1. When the frequency is relatively high, the overall size of the lens differs significantly from the unit size, leading to structural complexity; 2. The electromagnetic waves of both frequency bands propagate in the same area within the lens, meaning that adjusting any design parameter will simultaneously affect the radiation characteristics in both frequency bands, making it difficult to independently adjust the radiation characteristics of the two bands.

[0055] Based on the above principles, this embodiment provides a sandwich Luneburg lens antenna with independent adjustment capability for dual-frequency radiation characteristics. (Refer to...) Figure 1 The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics includes a first planar Luneburg lens, a second planar Luneburg lens, and a third planar Luneburg lens.

[0056] In this embodiment, the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens have a certain thickness, but they extend to a relatively large dimension on a plane perpendicular to the thickness direction, for example... Figure 1The first, second, and third plane Luneburg lenses are all cylindrical with a base radius greater than their height, and their base radii are equal. The centers of their bases lie on the same straight line. The overall shape of the three plane Luneburg lenses after assembly is still a cylinder, that is, the first, second, and third plane Luneburg lenses are all disk-shaped. Therefore, from a macroscopic perspective, the thickness of the first, second, and third plane Luneburg lenses can be ignored, and they can be regarded as plane figures respectively.

[0057] Figure 1 The "missing" part shown by the dashed line is used to illustrate the internal structure of the sandwich Luneburg lens antenna and does not mean that the actual sandwich Luneburg lens antenna must have such a "missing" part.

[0058] In this embodiment, refer to Figure 1 The X-axis and Y-axis are established with the plane where the second plane Luneburg lens is located, and the Z-axis is established perpendicular to the plane where the second plane Luneburg lens is located. The first plane Luneburg lens is located on the side where the Z-axis of the second plane Luneburg lens increases, and the third plane Luneburg lens is located on the side where the Z-axis of the second plane Luneburg lens decreases. That is, the first plane Luneburg lens and the third plane Luneburg lens are distributed on the upper and lower sides of the second plane Luneburg lens, thus forming a sandwich structure.

[0059] In this embodiment, the first planar Luneburg lens and the second planar Luneburg lens can be connected by glue or a special connection structure, and the second planar Luneburg lens and the third planar Luneburg lens can be connected by glue or a special connection structure, or the first planar Luneburg lens, the second planar Luneburg lens and the third planar Luneburg lens can be manufactured by an integrated molding process, so that the sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics can be formed as a whole.

[0060] Reference Figure 1 Air gap layers are provided between the first and second plane Luneburg lenses and between the second and third plane Luneburg lenses, meaning that the first and second plane Luneburg lenses and the second and third plane Luneburg lenses may not be completely tightly fitted.

[0061] In this embodiment, refer to Figure 1The structure of the first-plane Luneburg lens is the same as that of the third-plane Luneburg lens. However, the structure of the first-plane Luneburg lens differs from that of the second-plane Luneburg lens, and the structure of the third-plane Luneburg lens also differs from that of the second-plane Luneburg lens. Since the first-plane, second-plane, and third-plane Luneburg lenses are all Luneburg lenses, they all have the function of converting incident spherical waves into outgoing plane waves, thereby increasing beam gain and narrowing beamwidth. The first-plane and third-plane Luneburg lenses, using the same structure, can be used to propagate low-frequency electromagnetic waves while restricting the propagation of high-frequency electromagnetic waves. Using a second-plane Luneburg lens with a different structure can simultaneously support the propagation of both high and low frequency electromagnetic waves. Therefore, the sandwich Luneburg lens antenna formed by these lenses exhibits dual-frequency radiation characteristics. Since the first and third-plane Luneburg lenses share one structure, while the second-plane Luneburg lens has a different structure, it is convenient to adjust the radiation characteristics of the corresponding frequency band (e.g., low-frequency electromagnetic waves) by adjusting the parameters of the first and third-plane Luneburg lenses with the same structure, without affecting the overall radiation characteristics of the sandwich Luneburg lens antenna for other frequency bands (e.g., high-frequency electromagnetic waves). Similarly, by adjusting the parameters of the second-plane Luneburg lens with a different structure, the radiation characteristics of the corresponding frequency band (e.g., high-frequency electromagnetic waves) can be adjusted without affecting the overall radiation characteristics of the sandwich Luneburg lens antenna for other frequency bands (e.g., low-frequency electromagnetic waves), thus achieving independent adjustment capability for both frequency bands. Moreover, this heterogeneous design facilitates structural simplification, effectively reduces design and manufacturing difficulty, and minimizes the impact of dimensional errors caused by manufacturing tolerances.

[0062] In this embodiment, refer to Figure 2 The first and third plane Luneburg lenses have the same structure, both being a stack structure composed of dielectric rods. The second plane Luneburg lens is a structure composed of multiple cubic structural units.

[0063] In this embodiment, taking the first planar Luneburg lens as an example, a portion of its structure is as follows: Figure 3 As shown. (Refer to...) Figure 3 The first planar Luneburg lens comprises multiple dielectric rods distributed across various layers. Figure 3 The diagram shows four layers, all of which are parallel to the XoY plane. Multiple dielectric rods within the same layer are parallel to each other and arranged periodically. Periodic arrangement means that the distance between any two dielectric rods in the same layer is the same; in this embodiment, this distance is called the horizontal period, and the specific size of the horizontal period can be p = 6.25 mm.

[0064] Reference Figure 3 Different layers of dielectric rods are stacked together to form a three-dimensional orthogonal cuboid grid-shaped pile structure. The dielectric rods in any layer are spatially perpendicular to the dielectric rods in the adjacent layer, for example... Figure 3 The dielectric rod in the bottom layer is adjacent to the dielectric rod in the second layer from the bottom. The two dielectric rods are spatially perpendicular to each other. That is, if the dielectric rods of these two layers are projected onto a plane parallel to them (such as the XoY plane), the resulting projection is perpendicular.

[0065] Reference Figure 3 Each dielectric rod in any layer is offset relative to each dielectric rod in the layer between them by half a horizontal period. There is another layer between a given layer and its spaced-apart layer. For example, Figure 3 The dielectric rod at the bottom layer is not directly adjacent to the dielectric rod in the third layer (second layer from the top). There is another layer between them, namely the second layer from the bottom. Therefore, for Figure 3 For the dielectric rod located at the bottom layer, the third dielectric rod from the bottom (the second layer from the top) consists of the dielectric rods in the layer between each other. (Refer to...) Figure 3 The dielectric rods of the third layer from the bottom (the second layer from the top) are offset relative to the dielectric rod of the bottommost layer by half a horizontal period. For example, if the dielectric rods of these two layers are projected onto a plane parallel to them (e.g., the XoY plane), the resulting projection is still periodically distributed, but the corresponding period becomes half the horizontal period of a single layer. In other words, if viewed from a direction perpendicular to the XoY plane, one will see... Figure 3 The third layer of dielectric rods from the bottom (the second layer from the top) fills the gap between the dielectric rods in the bottom layer.

[0066] In this embodiment, refer to Figure 2 The first-plane and third-plane Luneburg lenses, which have a stacked structure, are also periodic in the thickness direction (or height direction, i.e., the Z-axis direction), for example, located in... Figure 3 The uppermost dielectric rod, and the dielectric rod above it ( Figure 3 The arrangement and orientation (not shown in the image) and location Figure 3 The bottommost layer of medium rods is identical. Therefore, from the perspective of thickness, the woodpile structure has a cycle of 4 layers. In this embodiment, this cycle, which is the total height of the 4 layers of medium rods, is called the vertical cycle. The specific size of the vertical cycle can be h = 8.84 mm. In this embodiment, all medium rods have the same height, so the height of one medium rod is equal to one-quarter of the vertical cycle. For example, the height of one medium rod is 2.21 mm.

[0067] In this embodiment, the first and third planar Luneburg lenses are each composed of 18 layers of dielectric rods stacked together, therefore the thickness (height) of both the first and third planar Luneburg lenses is 39.78 mm. The first and third planar Luneburg lenses can be manufactured using technologies such as 3D printing, wherein the dielectric rods in the first and third planar Luneburg lenses are made of nylon.

[0068] In this embodiment, the stack structure units of the first and third planar Luneburg lenses have frequency selectivity characteristics. In the low-frequency band, they can be equivalent to a uniform medium, thereby realizing their own low-frequency transmission function. In the high-frequency band, they exhibit a certain band-stop effect, so as not to affect the high-frequency transmission function of the second planar Luneburg lens, which is conducive to realizing independent dual-frequency adjustment.

[0069] In this embodiment, a portion of the structure of the second planar Luneburg lens, namely the cubic structural unit, is as follows: Figure 4 As shown. (Refer to...) Figure 2 The disc-shaped second-plane Luneburg lens has a central axis, which can divide the lens into multiple layers, with the center of each layer located on the central axis. In manufacturing the second-plane Luneburg lens, multiple independent cubic structural units can be created first. Then, individual layers within the second-plane Luneburg lens are manufactured. Specifically, multiple cubic structural units are arranged hierarchically around a central point, with each cubic structural unit located on a ring. This process of manufacturing individual layers is repeated multiple times to create multiple layers within the second-plane Luneburg lens. Finally, the centers of these layers are aligned and assembled together to obtain the second-plane Luneburg lens.

[0070] In this embodiment, a PCB material with a relative permittivity of 2.2 (e.g., Vanling F4B) can be used to fabricate the second planar Luneburg lens. Specifically, a single PCB substrate can be used to fabricate multiple cubic structural units to obtain a single layer in the second planar Luneburg lens; this process can be repeated on multiple PCB substrates to obtain multiple layers in the second planar Luneburg lens; and the multiple layers can be stacked together to obtain the second planar Luneburg lens.

[0071] In this embodiment, for a single layer in the second-plane Luneburg lens, the number of structural units contained in each ring gradually increases radially outward from its center (circle center). Specifically, the number of cubic structural units in each ring is num = (8 + (i-2) × 8), where the number of ring layers is obtained by counting outward from the center.

[0072] In this embodiment, the side length of the cubic structural unit is p = 2.5 mm, and the second planar Luneburg lens is composed of 4 layers of cubic structural units stacked together. Therefore, the thickness (height) of the second planar Luneburg lens is 10 mm.

[0073] In this embodiment, refer to Figure 4 Cylindrical air holes can be machined into some or all of the cubic structural units.

[0074] In this embodiment, refer to Figure 5 After assembling the first, second, and third planar Luneburg lenses and aligning their centers, their centers lie on the same straight line. This straight line is the central axis of the entire sandwich Luneburg lens antenna as a cylinder. Extending radially outward from this central axis by a certain distance (this distance can be half the base radius of the first, second, and third planar Luneburg lenses or other proportional values, for example, referring to…) Figure 5 The bottom radius of the first planar Luneburg lens is R1 = 75mm, and the extended distance is R2 = 37.5mm. This extends a certain spatial region, which is also a cylinder, referred to as the inner cylindrical region in this embodiment. The bottom radius of the inner cylindrical region is R2 = 37.5mm.

[0075] Reference Figure 5 The sandwich Luneburg lens antenna is a cylinder in shape, and the space it occupies is divided into an inner cylindrical area and an outer ring area.

[0076] In this embodiment, the components located in the inner cylindrical region and the components located in the outer annular region may have different specific structures.

[0077] For example, each dielectric rod located in the inner cylindrical region has a first dimensional parameter, and each dielectric rod located in the outer annular region has a second dimensional parameter. For example, both the first and second dimensional parameters represent the cross-sectional width of the dielectric rod, where the first dimensional parameter is specifically 4.5 mm and the second dimensional parameter is specifically 2.7 mm, meaning that each dielectric rod located in the inner cylindrical region is thicker than each dielectric rod located in the outer annular region.

[0078] For example, each cubic structural unit located in the inner cylindrical region is solid, meaning it does not have cylindrical air holes, while each cubic structural unit located in the outer annular region has cylindrical air holes. The cylindrical air holes are perpendicular to the plane where the second plane Luneburg lens is located, and the diameter of the cylindrical air holes is d = 0.64 mm.

[0079] In this embodiment, a second planar Luneburg lens composed of multiple cubic structural units is used, thereby making the structure of the second planar Luneburg lens different from that of the first and third planar Luneburg lenses, enabling independent adjustment of dual-frequency radiation characteristics. Furthermore, the period (e.g., horizontal period) of the metamaterial units constituting the first and third planar Luneburg lenses can be greater than the period (e.g., the side length of the cubic structural units) of the second planar Luneburg lens, thus ensuring that high-frequency electromagnetic waves propagate only within the second planar Luneburg lens, while low-frequency electromagnetic waves propagate within the first and third planar Luneburg lenses.

[0080] In this embodiment, a medium protrusion fixing structure (not shown in the figure) can be provided on the edges of the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens respectively. The medium protrusion fixing structure has through holes. Nylon screws are passed through the through holes of each medium protrusion fixing structure, and finally the nylon screws are tightened with nylon nuts, thereby mechanically connecting the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens.

[0081] In this embodiment, nylon gaskets can also be provided between the dielectric protrusion fixing structure of the first planar Luneburg lens and the dielectric protrusion fixing structure of the second planar Luneburg lens, and between the dielectric protrusion fixing structure of the third planar Luneburg lens and the dielectric protrusion fixing structure of the second planar Luneburg lens. Nylon screws pass through the nylon gaskets, thereby forming air gap layers between the first planar Luneburg lens and the second planar Luneburg lens, and between the third planar Luneburg lens and the second planar Luneburg lens.

[0082] In this embodiment, as Figure 6 As shown, the sandwich Luneburg lens antenna also includes multiple dual-frequency feed antennas. (Refer to...) Figure 6 These dual-frequency feed antennas are distributed around the edge of the second-plane Luneburg lens and are mechanically connected to the second-plane Luneburg lens.

[0083] In this embodiment, refer to Figure 6 Each dual-frequency feed antenna is located on the same plane, and the main radiation direction of each dual-frequency feed antenna points to the center of the second-plane Luneburg lens. The dual-frequency feed antennas can be uniformly arranged on the second-plane Luneburg lens. For example, the angle Δφ between the main radiation directions of any two adjacent dual-frequency feed antennas is equal in magnitude. In this embodiment, Δφ = 40°, which allows the radiation beam generated by each feed to uniformly cover a certain area.

[0084] In this embodiment, each dual-frequency feed antenna has one high-frequency port and one low-frequency port. Since there are 5 dual-frequency feed antennas in this embodiment, there are a total of 10 ports. (Refer to...) Figure 6The high-frequency ports are named from left to right as ports 1 to 5, and the low-frequency ports are named from left to right as ports 6 to 10.

[0085] In this embodiment, the dual-frequency feed antenna is used as a feed antenna to feed the sandwich Luneburg lens antenna. Specifically, exciting one of the dual-frequency feed antennas enables it to generate a spherical wave, which is then converted into a plane wave by the second planar Luneburg lens to output a corresponding beam. By switching the number of dual-frequency feed antennas to be excited, a wide-angle beam can be achieved. By switching the position of the dual-frequency feed antennas to be excited, a multi-beam scanning effect can be achieved, for example... Figure 6 The sandwich Luneburg lens antenna shown can achieve multi-beam scanning within a range of ±80° by switching between the dual-frequency feed antennas during scanning. If each dual-frequency feed antenna is evenly arranged on the second plane Luneburg lens, a wide-angle uniform multi-beam scanning effect can be achieved.

[0086] In this embodiment, the structure of the dual-frequency feed antenna is as follows: Figure 7 As shown. (Refer to...) Figure 7 The dual-frequency feed antenna consists of two nested parts: a patch antenna and a metal open waveguide antenna. Specifically, refer to... Figure 7 The patch antenna has an opening, and the metal open waveguide antenna passes through the opening of the patch antenna, thus being nested in the patch antenna to form a whole, becoming a dual-frequency feed antenna.

[0087] In this embodiment, the metal open waveguide antenna operates at a higher first frequency band (e.g., above 20 GHz, specifically 24 GHz), while the patch antenna operates at a lower second frequency band (e.g., below 10 GHz, specifically 5.8 GHz).

[0088] In this embodiment, the structures of the patch antenna and the metal open waveguide antenna are as follows: Figure 8 As shown. (Refer to...) Figure 8 The patch antenna includes a substrate, a metal patch, a metal ground, and a second SMA connector. The metal patch is located on one side of the substrate (facing the second planar Luneburg lens), and the metal ground is located on the other side of the substrate. The second SMA connector is mounted on the substrate. The outer conductor of the second SMA connector is in electrical contact with the metal ground, and the inner conductor of the second SMA connector passes through the substrate and is in electrical contact with the metal patch (the inner conductor of the second SMA connector is not in electrical contact with the metal ground).

[0089] Both the substrate and the metal patch can be rectangular, and the substrate model is RO4003C.

[0090] In this embodiment, refer to Figure 8The metal open-ended waveguide antenna has an open end and a metal short-circuit wall at the other end. The open end of the metal open-ended waveguide antenna protrudes slightly from the substrate of the patch antenna. The edge of the second planar Luneburg lens has slots (not shown in the figure) whose shape and size match this protruding part of the metal open-ended waveguide antenna. This allows the protruding part of the metal open-ended waveguide antenna to be embedded into the slot of the second planar Luneburg lens, thus forming a mechanical connection. This allows the dual-frequency feed antenna to be mounted entirely on the edge of the second planar Luneburg lens. In this embodiment, the number of slots in the second planar Luneburg lens is the same as the number of dual-frequency feed antennas; that is, one dual-frequency feed antenna is installed in each slot.

[0091] In this embodiment, refer to Figure 7 and Figure 8 The dual-band feed antenna also features a first SMA connector. (See reference...) Figure 7 The first SMA connector is mounted on one end of the metal short-circuit wall outside the metal open waveguide antenna.

[0092] In this embodiment, refer to Figure 8 The metal open waveguide antenna has a pair of trapezoidal metal ridges inside, each trapezoidal metal ridge including a longer base, a shorter base, a sloping waist and a right-angled waist.

[0093] Reference Figure 8 The longer base of the trapezoidal metal ridge faces the outside of the metal open waveguide antenna. The sloping waist of the trapezoidal metal ridge extends from the opening of the metal open waveguide antenna to the inside of the metal open waveguide antenna. The right-angle waist of the trapezoidal metal ridge is connected to the metal short-circuit wall of the metal open waveguide antenna. The shorter bases of the two trapezoidal metal ridges are opposite each other.

[0094] Reference Figure 8 The trapezoidal metal ridge has two stepped notches at its shorter base, with a width of b1.

[0095] Reference Figure 8 The trapezoidal metal ridge at the top has a through hole perpendicular to the bottom edge. The inner conductor of the first SMA connector passes through the through hole of the trapezoidal metal ridge and makes electrical contact with another trapezoidal metal ridge (there is no electrical contact between the trapezoidal metal ridge at the top and the inner conductor of the first SMA connector). The inner conductor of the first SMA connector also makes electrical contact with the metal patch in the patch antenna. The outer conductor of the first SMA connector can be fixed to the outside of the metal open waveguide antenna by screws or other components.

[0096] In this embodiment, Figure 7 and Figure 8In the dual-band feed antenna shown, the first SMA connector serves as the high-frequency port, and the second SMA connector serves as the low-frequency port. The high-frequency port is used to receive power from external devices at a higher first frequency band, and the low-frequency port is used to receive power from external devices at a lower second frequency band. For example, Figure 6 In this example, port 3, used as a high-frequency port, and port 8, used as a low-frequency port, are two ports in the same dual-frequency feed antenna. Port 3 is the first SMA connector, and port 8 is the second SMA connector.

[0097] In this embodiment, Figure 7 and Figure 8 The dual-band feed antenna shown can simultaneously receive feeds from two frequency bands and generate spherical waves to feed three planar Luneburg lenses. The electromagnetic waves generated by the higher first frequency band feed will propagate through the second planar Luneburg lens, while the electromagnetic waves generated by the lower second frequency band feed will also propagate through the first and third planar Luneburg lenses.

[0098] In this embodiment, the technical advantage of the dual-frequency feed antenna is mainly due to its structure. Figure 7 and Figure 8 The specific values ​​of the parameters are shown in Table 1.

[0099] Table 1

[0100] <![CDATA[l0]]> <![CDATA[w0]]> <![CDATA[l1]]> <![CDATA[w1]]> <![CDATA[l2]]> <![CDATA[w2]]> 40mm 23mm 25.6mm 15.9mm 12.67mm 6.32mm th <![CDATA[d0]]> <![CDATA[d1]]> <![CDATA[d2]]> <![CDATA[d3]]> <![CDATA[d4]]> 1.52mm 14mm 9.45mm 2.65mm 0.45mm 4.25mm dr <![CDATA[b1]]> <![CDATA[b2]]> <![CDATA[b3]]> 2.6mm 1.13mm 0.85mm 0.51mm

[0101] A comparison of the sandwich Luneburg lens antenna in this embodiment with the propagation of electromagnetic waves of different frequencies inside a conventional broadband metamaterial planar Luneburg lens. Figure 9 As shown. Among them Figure 9 The upper part shows the propagation of electromagnetic waves of different frequencies inside an existing broadband metamaterial planar Luneburg lens, while the lower part shows the propagation of electromagnetic waves of different frequencies inside the sandwich Luneburg lens antenna in this embodiment.

[0102] pass Figure 1 , Figure 2 , Figure 5 and Figure 6 The sandwich Luneburg lens antenna shown in this embodiment has the following technical advantages:

[0103] (1) High gain, narrow beam, low sidelobe: Through the refraction of the Luneburg lens, the incident spherical wave can be converted into the outgoing plane wave at both high and low frequencies, thereby increasing the gain, narrowing the beam, and reducing the sidelobe level.

[0104] (2) Wide scanning angle: By switching the direction as well as The dual-frequency feed antenna can achieve multi-beam scanning.

[0105] (3) Simple structure and easy to manufacture: The antenna proposed in this embodiment can be easily manufactured using mature 3D printing, CNC machine tool processing, and circuit board processing technologies. Furthermore, due to the sandwich design of the lens, a heterogeneous metamaterial structure can be used to build the lens. Compared to the second-layer planar Luneburg lens, the metamaterials used in the first and third planar Luneburg lenses can be composed of structural units with larger periods. This avoids using broadband metamaterials covering both low and high frequency bands to construct the entire lens, greatly simplifying the lens structure.

[0106] (4) Capable of generating dual-frequency radiation beams with a large frequency ratio: Existing dual-frequency Luneburg lenses all employ a single type of broadband metamaterial structure that simultaneously covers both low and high frequencies. The period of the structural unit needs to be smaller than the high-frequency wavelength, while the lens size needs to be several times larger than the low-frequency wavelength. When the two frequencies have a large frequency ratio, the complexity of the lens structure will increase significantly. Due to limitations such as structural complexity, existing dual-frequency Luneburg lens antennas have a relatively small frequency ratio, generally less than 2:1. However, through the use of sandwich design and heterogeneous metamaterial schemes, the proposed Luneburg lens antenna has a large frequency ratio. In this embodiment, the frequency ratio of the center frequencies of the two bands is approximately 25.5:5.8, which is approximately 4.4:1.

[0107] (5) Independent Adjustment Capability of Dual-Frequency Radiation Characteristics: In this embodiment, the dual-frequency feed antenna radiates both high-frequency and low-frequency electromagnetic waves relative to the proposed sandwich Luneburg lens. Ideally, its electromagnetic field propagation region is as follows: Figure 6 As shown. In the low-frequency band, the stack structure applied to the first and third planar Luneburg lenses can be equivalent to a homogeneous medium using the equivalent medium theory. Similarly, the broadband metamaterial structure with cylindrical through-holes applied to the second planar Luneburg lens can also be equivalent to a homogeneous medium in the low-frequency band. The air gap layer is negligible because it is much smaller than the wavelength of low-frequency electromagnetic waves. Therefore, the propagation area of ​​low-frequency electromagnetic waves inside the lens encompasses the entire lens. In the high-frequency band, the stack structure applied to the first and third planar Luneburg lenses exhibits a certain band-stop effect. This band-stop effect, combined with the isolation effect of the air gap layer on high-frequency electromagnetic waves, effectively suppresses the propagation of high-frequency electromagnetic waves. The presence of the first and third planar Luneburg lenses and the air gap layer confines the propagation range of high-frequency electromagnetic waves within the second planar Luneburg lens. By adjusting the overall thickness of the interlayer Luneburg lens while keeping the thickness of the second-layer planar Luneburg lens constant, the low-frequency radiation characteristics can be independently adjusted; while by adjusting the thickness of the second-layer planar Luneburg lens while keeping the overall thickness of the interlayer Luneburg lens constant, the high-frequency radiation characteristics can be independently adjusted.

[0108] The designed sandwich Luneburg lens antenna with independent adjustment capability for high frequency ratio dual-frequency radiation characteristics was simulated, fabricated, and measured. The simulation software was CST Studio Suite. The simulation and measurement results are as follows: Figures 10-18 As shown.

[0109] Figure 10 The diagram shows the simulation and measured results of the return loss versus operating frequency for the sandwich Luneburg lens antenna in this embodiment. Figure 10 It is clear that the measured results are in high agreement with the simulation results. In the frequency ranges of 5.7 GHz to 5.9 GHz and 18.7 GHz to 27.3 GHz, the measured reflection coefficients at all ports are below -10 dB. The relative impedance bandwidths at low and high frequencies are 3.4% and 37.4%, respectively. The operating bandwidth, the intersection of the impedance bandwidth and the 3 dB gain bandwidth, lies between 5.7 GHz and 5.9 GHz and between 23.1 GHz and 27.3 GHz. The relative operating bandwidths are 3.4% and approximately 16.8%, respectively. Figure 10 In the diagram, the operating bandwidth is highlighted in purple. The 3dB gain bandwidth is described later.

[0110] Figure 11 The isolation coefficients between the ports are shown. At higher frequencies, the coupling between the two ports of the rectangular patch antenna and the rectangular metal open waveguide antenna, both belonging to the same dual-frequency feed antenna, is strongest, with maximum simulated and measured values ​​of -16.53 dB and -23.58 dB, respectively. At higher frequencies, the isolation between port 1 and port 5 is worst. Within the operating frequency band, the highest simulated |S 15 The value is -13.62dB, and the measured value is -18.42dB. The isolation coefficients between other ports are all below -25dB.

[0111] Figure 12 The radiation patterns of ports 6-10 in the XoY plane at 5.8 GHz are shown. These five ports produce beams with directions of 0°, ±40°, and ±80°, with a scan loss of 1.54 dB. The 3 dB beamwidth of these beams is approximately 20°, and the sidelobe level is close to -15 dB.

[0112] Figure 13 and Figure 14This embodiment demonstrates stable high-gain multi-beam radiation generated by the sandwich Luneburg lens antenna at 24 GHz and 27 GHz, with measured results highly consistent with simulation data. The 3dB beamwidths of the central beam at 24 GHz and 27 GHz are 7.33° and 6°, respectively. The sidelobe level of the central beam is approximately -15 dB; however, the beam pointing at ±80° has a higher sidelobe level of approximately -7 dB due to the influence of the dual-frequency feed antenna on the opposite side. This influence also leads to an effective aperture loss at the maximum scan angle, resulting in a scan loss of 3.71 dB.

[0113] Figure 15 and Figure 16 This demonstrates the ability of the sandwich Luneburg lens antenna in this embodiment to independently adjust its dual-frequency radiation characteristics. This characteristic can be attributed to the sandwich structure used in the Luneburg lens antenna design and the separation of the propagation regions of the radiated electromagnetic waves in the two frequency bands. Figure 15 The results show that by adjusting the thickness H1 of the Luneburg lens antenna while keeping the thickness H2 of the second-layer planar Luneburg lens constant, the low-frequency radiation characteristics can be independently adjusted. Figure 16 The results show that the radiation characteristics of the high-frequency band can be independently adjusted by adjusting H2 while keeping H1 constant.

[0114] Figure 17 The simulation results show the electric field distribution on the XoZ plane at different frequencies. Figure 17 (a) shows the electric field distribution at an operating frequency of 5.8 GHz. Figure 17 (a) It can be seen that the electromagnetic wave propagates over the entire lens at this frequency. Figure 17 (b) shows the electric field distribution at an operating frequency of 24 GHz. Figure 17 (b) It is evident that the electromagnetic wave propagation range at this frequency is limited to the second-layer planar Luneburg lens. This indicates that, through a sandwich design with a stacked structure, the proposed Luneburg lens can effectively realize the aforementioned concept of separating the propagation regions of the two frequency bands of radiated electromagnetic waves for independent control.

[0115] The gain-frequency relationship of all ports is as follows: Figure 18 As shown. Overall, the simulation and experimental results agree well. All ports 6-10 reach peak gain at 5.8 GHz, with a maximum gain variation of 1.1 dB in the low-frequency band. In the high-frequency band, the highest measured gain is 18.8 dBi, and the gain variation is less than 3 dB in the frequency range of 23.1 GHz to 27.3 GHz. Port 1 shows the most significant gain fluctuation, with a measured fluctuation of 2.8 dB.

[0116] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," and "right" used in this disclosure are only relative to the relative positional relationships of the components of this disclosure in the accompanying drawings. The singular forms "a," "an," and "the" used in this disclosure are also intended to include the plural forms, unless the context clearly indicates otherwise. Moreover, unless otherwise defined, all technical and scientific terms used in this embodiment have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this embodiment specification is only for describing particular embodiments and is not intended to limit the invention. The term "and / or" as used in this embodiment includes any combination of one or more of the associated listed items.

[0117] It should be understood that although the terms first, second, third, etc., may be used to describe various elements in this disclosure, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from each other. For example, a first element may also be referred to as a second element without departing from the scope of this disclosure, and similarly, a second element may also be referred to as a first element. The use of any and all instances or exemplary language (“e.g.,” “such as,” etc.) provided in this embodiment is intended only to better illustrate embodiments of the invention and, unless otherwise required, does not impose a limitation on the scope of the invention.

[0118] It should be recognized that embodiments of the present invention can be implemented or carried out by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable storage medium. The method can be implemented using standard programming techniques—including a non-transitory computer-readable storage medium configured with a computer program, wherein such a storage medium causes the computer to operate in a specific and predefined manner—according to the methods and drawings described in the specific embodiments. Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system. However, if desired, the program can be implemented in assembly or machine language. In any case, the language can be a compiled or interpreted language. Furthermore, for this purpose, the program can run on a programmed application-specific integrated circuit (ASIC).

[0119] Furthermore, the procedures described in this embodiment can be performed in any suitable order unless otherwise indicated by this embodiment or clearly contradicted by the context. The procedures (or variations and / or combinations thereof) described in this embodiment can be executed under the control of one or more computer systems configured with executable instructions, and can be implemented by hardware or a combination thereof as code (e.g., executable instructions, one or more computer programs, or one or more applications) that commonly executes on one or more processors. A computer program includes multiple instructions executable by one or more processors.

[0120] Furthermore, the method can be implemented in any suitable type of computing platform, including but not limited to personal computers, minicomputers, mainframes, workstations, networked or distributed computing environments, standalone or integrated computer platforms, or in communication with charged particle tools or other imaging devices, etc. Aspects of the invention can be implemented as machine-readable code stored on a non-transitory storage medium or device, whether removable or integrated into a computing platform, such as a hard disk, optical read and / or write storage medium, RAM, ROM, etc., such that it is readable by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the processes described herein. Furthermore, the machine-readable code, or portions thereof, can be transmitted via wired or wireless networks. The invention of this embodiment includes these and other different types of non-transitory computer-readable storage media when such media comprises instructions or programs that implement the steps above in conjunction with a microprocessor or other data processor. When programmed according to the methods and techniques of the invention, the invention also includes the computer itself.

[0121] A computer program can be applied to input data to perform the functions of this embodiment, thereby transforming the input data to generate output data stored in non-volatile memory. The output information can also be applied to one or more output devices, such as a display. In a preferred embodiment of the invention, the transformed data represents physical and tangible objects, including specific visual depictions of physical and tangible objects generated on the display.

[0122] The above are merely preferred embodiments of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, as long as they achieve the technical effects of the present invention by the same means, should be included within the scope of protection of the present invention. Within the scope of protection of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A sandwich Luneburg lens antenna with independent adjustment capability for dual-frequency radiation characteristics, characterized in that, The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics includes: A first-plane Luneburg lens, a second-plane Luneburg lens, and a third-plane Luneburg lens; the first-plane Luneburg lens is located above the second-plane Luneburg lens, and the third-plane Luneburg lens is located below the second-plane Luneburg lens. The structure of the first-plane Luneburg lens is the same as that of the third-plane Luneburg lens, but different from that of the second-plane Luneburg lens. Multiple dual-frequency feed antennas are provided; each dual-frequency feed antenna is distributed and disposed on the edge of the second planar Luneburg lens and is mechanically connected to the second planar Luneburg lens; each dual-frequency feed antenna includes a patch antenna and a metal open waveguide antenna; the metal open waveguide antenna operates at a frequency in a first frequency band, and the patch antenna operates at a frequency in a second frequency band, wherein the first frequency band is higher than the second frequency band; the patch antenna has an opening; the metal open waveguide antenna passes through the opening of the patch antenna, thereby being nested in the patch antenna.

2. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 1, characterized in that: Both the first planar Luneburg lens and the third planar Luneburg lens are woodpile structures; The second planar Luneburg lens comprises multiple cubic structural units; The edges of the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens are respectively provided with dielectric protrusion fixing structures, and the dielectric protrusion fixing structures are provided with through holes; The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics also includes nylon screws, nylon nuts, and nylon washers; the nylon washers are placed between two corresponding dielectric protrusion fixing structures, the nylon screws pass through the through holes of the dielectric protrusion fixing structures and the nylon washers, and the nylon nuts fix the nylon screws.

3. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 2, characterized in that: The first planar Luneburg lens and the third planar Luneburg lens each include a plurality of dielectric rods with rectangular cross sections, each dielectric rod being located in a corresponding layer, and the dielectric rods in each layer being stacked. The dielectric rods in the same layer are parallel to each other and arranged periodically in a horizontal cycle; The dielectric rod in any layer is spatially perpendicular to the dielectric rod in the adjacent layer; Each of the dielectric rods in any layer is offset relative to each of the dielectric rods in the layer between them by half a horizontal period.

4. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 2, characterized in that: The first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens are all disc-shaped; The first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens have the same radius and their centers are aligned. The cubic structural units in the second planar Luneburg lens are arranged in a multi-layered ring around the center of the disk.

5. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 3, characterized in that: Each of the dielectric rods located in the inner cylindrical region has a first dimensional parameter, and each of the dielectric rods located in the outer annular region has a second dimensional parameter; Each of the cubic structural units located in the inner cylindrical region is solid, and each of the cubic structural units located in the outer annular region is provided with a cylindrical air hole, which is perpendicular to the plane where the second plane Luneburg lens is located. The inner cylindrical region is the spatial region extending outward from the center axis of the cylinder formed by the stacking of the first planar Luneburg lens, the second planar Luneburg lens, and the third planar Luneburg lens. The outer annular region is the spatial region in the cylinder other than the inner cylindrical region.

6. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 1, characterized in that: The edge of the second planar Luneburg lens has multiple slots; the shape and size of the slots match one end of the metal open waveguide antenna. One end of the metal open waveguide antenna is an opening, and the other end is a metal short-circuit wall; The opening end of the metal open waveguide antenna is embedded in the slot, thereby forming a mechanical connection with the second planar Luneburg lens; The other end of the metal open waveguide antenna is fitted with a first SMA connector.

7. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 6, characterized in that: The metal open waveguide antenna has a pair of trapezoidal metal ridges inside; The longer base of the trapezoidal metal ridge faces outward from the metal open waveguide antenna, and the sloping waist of the trapezoidal metal ridge extends from... The opening of the metal open waveguide antenna extends into the interior of the metal open waveguide antenna; the right-angle waist of the trapezoidal metal ridge is connected to the metal short-circuit wall of the metal open waveguide antenna; the upper part of the right-angle waist of the trapezoidal metal ridge has two stepped grooves. The shorter bases of the two trapezoidal metal ridges are opposite each other; One of the trapezoidal metal ridges has a through hole perpendicular to the bottom edge. The inner conductor of the first SMA connector passes through the through hole of the trapezoidal metal ridge and forms an electrical contact with the other trapezoidal metal ridge. The outer conductor of the first SMA connector is connected to the outside of the metal open waveguide antenna.

8. The sandwich Luneburg lens antenna with independent adjustment capability of dual-frequency radiation characteristics according to claim 6, characterized in that: The patch antenna includes a substrate, a metal patch, a metal ground, and a second SMA connector. The metal patch is disposed on one side of the substrate, and the metal ground is disposed on the other side of the substrate; The inner conductor of the second SMA connector is in electrical contact with the metal patch, and the outer conductor of the second SMA connector is in electrical contact with the metal ground.

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