Mutual coupling improved microwave and millimeter wave common-aperture antenna based on electromagnetic band gap multiplexing

Abstract

The invention discloses a mutual coupling improved microwave and millimeter wave common-aperture antenna based on electromagnetic band gap multiplexing, particularly relates to the technical field of microwave and millimeter wave communication, and solves the problems that most of microwave and millimeter wave common-aperture antenna design schemes in the prior art cannot apply a microwave MIMO (Multiple Input Multiple Output) technology; in the prior art, MIMO application is not taken into collaborative design consideration, a solution for MIMO performance loss caused by mutual coupling and the like is lacked, and due to the restriction between microwave and millimeter wave antenna designs, the technical problems of bandwidth reduction, gain reduction, beam forming capability deficiency and the like of sub-antennas are difficult to avoid; according to the technical scheme, extra functions are achieved by multiplexing millimeter wave antennas, mutual coupling between microwave MIMO antennas is restrained, and then the MIMO performance enhancement effect is achieved; the performance of the millimeter wave antenna is reinforced by multiplexing the structure of the microwave antenna part; according to the invention, the performance of the dual-band antenna is improved on the premise of avoiding performance loss.

Description

Technical Field

[0001] The invention relates to the field of microwave and millimeter wave communications, and in particular to a mutually coupled improved microwave and millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing. Background Art

[0002] With the growing development of the Internet of Things era, traditional microwave spectrum resources are insufficient to adapt to dense wireless terminal connections and are difficult to meet the needs of low latency. Millimeter wave technology can improve this situation, but some of its inherent defects, such as high attenuation and weak penetration, mean that it does not have the ability to meet all communication needs alone. Therefore, microwave and millimeter wave collaborative networking will be an inevitable development trend of future communication technology. However, as far as terminal equipment is concerned, discrete layout of microwave and millimeter wave antenna arrays will occupy a lot of internal space of the equipment, which is difficult to adapt to the development trend of small and thin design. Integrating millimeter wave antenna arrays and microwave antennas into the same physical aperture (i.e., realizing co-aperture antennas) can effectively resolve the above dilemma. However, most of the reported microwave / millimeter wave co-aperture design schemes cannot apply microwave MIMO technology. In the few design schemes that integrate microwave MIMO antennas and millimeter wave antennas, the focus is only on the concept of co-aperture integration itself, and there is no clear requirement for collaborative design for the realization of microwave MIMO technology. Therefore, there is a lack of solutions to the problem of MIMO performance loss after co-aperture integration. For example, when multiple units are used, strong mutual coupling causes changes in the radiation direction pattern and increases in the channel bit error rate. In a common aperture environment, a more complex working environment will aggravate the problem, deteriorate the performance of the microwave antenna, and even interfere with antennas in other frequency bands.

[0003] At the same time, the problem of "multiple antennas restraining each other" in the existing microwave millimeter wave co-aperture design scheme cannot be ignored, especially for relatively large microwave antennas, which often face one or more problems of bandwidth reduction, gain reduction, and profile increase; and millimeter wave antennas are often limited by cramped layout space, asymmetric working environment, non-independent feeding channels, etc., which lead to the loss of beamforming capability. The two existing mainstream co-planar co-aperture integration schemes are used as examples to illustrate as follows: the embedded scheme embeds the millimeter wave antenna array into the microwave antenna unit. At this time, the microwave antenna radiation structure suffers large-scale occupational damage, causing the original radiation mode of the microwave antenna to be interfered with or lost. The structural reuse scheme usually reuses the main structures such as the radiation surface or feeding of the microwave antenna directly into the millimeter wave antenna array. At this time, the millimeter wave array is severely restricted by the microwave antenna structure, and independent feeding of each unit is almost impossible to achieve, resulting in the lack of phased beam scanning capability of the millimeter wave array.

[0004] Therefore, most of the existing microwave millimeter-wave co-aperture antenna design schemes are unable to apply microwave MIMO technology. Among the limited adaptable schemes, MIMO applications are not taken into consideration in collaborative design, and there is a lack of solutions to the MIMO performance loss problem caused by mutual coupling. In addition, due to the constraints between microwave and millimeter-wave antenna designs, it is difficult to avoid one or more problems of bandwidth reduction, gain reduction, and lack of beamforming capability in sub-antennas. Summary of the invention

[0005] Therefore, the present invention solves the problem that most of the microwave millimeter wave co-aperture antenna design schemes in the prior art cannot apply microwave MIMO technology, and in the limited adaptable schemes, MIMO applications are not included in the collaborative design considerations, and there is a lack of solutions to the MIMO performance loss problem caused by mutual coupling, etc., and due to the constraints between the microwave and millimeter wave antenna designs, it is difficult to apply the technical problems of avoiding bandwidth reduction, gain reduction, and lack of beamforming capability in sub-antennas; the mutual coupling improved microwave millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing provided by the present invention realizes the integration of microwave MIMO antenna and phased beam scanning millimeter wave antenna under the concept of microwave millimeter wave antenna co-aperture integration, and on this basis, additional functions are realized by multiplexing millimeter wave antennas, so as to suppress the mutual coupling between microwave MIMO antennas and obtain the MIMO performance enhancement effect; further, by multiplexing part of the microwave antenna structure, the performance of the millimeter wave antenna is reinforced, so that both dual-band antennas can obtain a certain performance improvement under the premise of avoiding performance loss.

[0006] The present invention provides a mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing, comprising a top metal structure, a first dielectric substrate, a metal ground, a second dielectric substrate and a feeding layer metal structure arranged in sequence from top to bottom; the top metal structure comprises two rectangular metal patches arranged symmetrically on the left and right.

[0007] Furthermore, each of the two rectangular metal patches is provided with a row of grounding holes, long strip grooves and feeding probes; the rectangular metal patches are connected to the metal ground through the grounding holes.

[0008] Furthermore, the grounding hole, the long strip groove and the feeding probe are arranged in sequence from the inside to the outside of the rectangular metal patch.

[0009] Furthermore, the feeding probe passes downward through the first dielectric substrate, the metal ground, and the second dielectric substrate, and the bottom of the feeding probe is connected to the metal structure of the feeding layer.

[0010] Furthermore, a row of four-unit millimeter wave antenna arrays is arranged between the two rectangular metal patches.

[0011] Furthermore, each unit millimeter wave antenna includes two small square metal patches symmetrically arranged front and back, each of the small square metal patches is provided with slender metal branches on both sides, and each of the small square metal patches is provided with a metallized via; the small square metal patch is connected to the metal ground through the metallized via.

[0012] Furthermore, a short groove is provided in the metal ground in an area corresponding to the gap between the two small square metal patches.

[0013] Furthermore, a long strip groove and a row of evenly distributed grounding holes on two rectangular metal patches in the top metal structure are excited by signals fed into the ports 1 and 2 through feeding probes, respectively, to form two microwave planar inverted-F antenna units.

[0014] Furthermore, a row of four-unit millimeter-wave antenna arrays located in the middle of the top metal structure is composed of eight mushroom-shaped structures, each of which is composed of two mushroom-shaped structures, which are composed of small square metal patches, slender metal branches and metallized vias. After the signals are fed into the independent ports, they are excited by short slot coupling in the metal ground.

[0015] Furthermore, the length of the long strip groove in the vertical direction is 0.7λ g -0.75λ g ,λ g is the wavelength of the waveguide corresponding to the center frequency of the microwave frequency band, and its width is 0.04λ g -0.06λ g , 0.3λ away from the edge of the rectangular metal patch on one side g -0.35λ g ; In each mushroom-shaped structure, the small square metal patch is 0.15λ long in the horizontal direction g -0.2λ g , width is 0.08λ g -0.1λ g , the length of the slender metal branch is 0.05λ g -0.07λ g , with a width of 0.015λ g -0.02λ g , the diameter of the metallized via is 0.013λ g -0.015λ g The distance between each two mushroom-shaped structures is 0.02λ g -0.03λ g .

[0016] Furthermore, for the common aperture antenna structure, in the millimeter wave frequency band, every two mushroom-shaped structures in the present invention form a millimeter wave antenna unit, and the short slot coupling port between the two mushroom-shaped structures is used to feed the signal to realize the unit excitation. The millimeter wave antenna unit operates in the 26.3GHz to 29.8GHz frequency band and has two working modes, namely, quasi-TM similar to traditional patches and 01 quasi-inverting TM similar to traditional patch 02 Four millimeter-wave antenna units are arranged linearly in the vertical direction to form a four-unit antenna array, and the radiation phase is controlled based on the independent feeding port to obtain the array beamforming capability. During the operation of the millimeter-wave array, the metal walls of the microwave planar inverted F antennas on both sides of the array are reused as surface wave suppression structures to improve the array gain and radiation pattern.

[0017] In the microwave frequency band, the two microwave planar inverted F antenna units in the present invention are arranged symmetrically in the horizontal direction and have two working modes, namely, TM 3 / 2,0 The two radiation modes are combined to form a microwave 4.9GHz frequency band. When the port of microwave unit one is fed with a signal and the port of microwave unit two is connected to a matching load, the signal excites the rectangular metal patch in microwave unit one, forming the radiation of microwave unit one. When microwave unit one radiates, part of the signal is superimposed on microwave unit two through path coupling to form mutual coupling between the two units. The weaker the mutual coupling, the smaller the impact on the radiation of unit two itself. When the port of microwave unit two is fed with a signal and the port of microwave unit one is connected to a matching load, the process is the same as above. In this signal transmission process, the mushroom-shaped structure located between the two microwave units presents a high impedance characteristic near a specific frequency band, which will effectively suppress the microwave coupling signal and form a signal transmission stop band. The frequency band in which the transmission stop band appears can be fine-tuned by adjusting the horizontal length of the small square metal patch of the main body of the mushroom-shaped structure and the diameter of the metallized via. Furthermore, by adding slender metal branches to both sides of the mushroom-shaped structure, the stopband frequency control range can be increased by adjusting the length of the slender metal branches. At the same time, the structure is a high impedance structure in the vertical direction, so the length change in the horizontal direction does not affect the millimeter wave antenna operation in the vertical direction. Ultimately, the mushroom-shaped structure group, that is, the millimeter wave antenna array, will significantly improve the mutual coupling of the two-unit MIMO planar inverted F antenna and enhance the radiation performance.

[0018] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0019] 1. The mutually coupled improved microwave millimeter-wave co-aperture antenna based on electromagnetic band gap multiplexing provided by the present invention is based on the design concept of structural multiplexing. In the environment of co-aperture integration of microwave MIMO antennas and millimeter-wave phased array antennas, the millimeter-wave antenna is multiplexed into a decoupled electromagnetic band gap of a microwave antenna, and the microwave antenna is multiplexed into a surface wave suppression structure of a millimeter-wave antenna. This not only avoids the problem of sub-antenna performance deterioration that most traditional co-aperture antenna designs will have, but also significantly improves the mutual coupling between microwave antenna units.

[0020] 2. The present invention provides a mutually coupled improved microwave millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing, wherein the millimeter wave antenna unit is composed of a pair of mushroom-shaped structures with slender branches loaded on the sides, and feeding and phase control are achieved through slot coupling signals; four millimeter wave antenna units are arranged vertically to form a scanning array, and the array operating frequency is controlled by the vertical related dimensions of the millimeter wave unit structure.

[0021] 3. The mutually coupled improved microwave millimeter wave common-aperture antenna based on electromagnetic band gap multiplexing provided by the present invention, the millimeter wave array composed of a mushroom-shaped structure group, acts as a decoupled electromagnetic band gap of the microwave antenna, suppresses the surface wave coupling between microwave antenna units based on its band-stop characteristics, and introduces a mutual coupling zero point into the microwave frequency band. The frequency of the mutual coupling zero point can be controlled by adjusting the horizontal length of the mushroom-shaped structure main patch and the diameter of the central via hole of the mushroom-shaped structure.

[0022] 4. The mutually coupled improved microwave millimeter wave co-aperture antenna based on electromagnetic band gap multiplexing provided by the present invention has slender branches loaded on the sides of the mushroom-shaped structure group (i.e., the millimeter wave antenna array). The slender branches present high impedance characteristics in the vertical direction. By adjusting the length of the slender branches in the horizontal direction, the mutual coupling zero point frequency adjustment range of the microwave frequency band can be further expanded without affecting the performance of the millimeter wave antenna.

[0023] 5. The microwave millimeter-wave co-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing provided by the present invention adopts a planar inverted F antenna type in which two microwave units are symmetrically arranged in the horizontal direction and are respectively located on both sides of the millimeter-wave array. The metal wall in the unit structure constitutes a surface wave suppression structure of the millimeter-wave array, thereby improving the radiation performance of the millimeter-wave antenna array.

[0024] 6. The mutually coupled improved microwave millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing provided by the present invention has dual antennas with orthogonal polarization directions, the millimeter wave antenna is polarized in the vertical direction, the microwave antenna is polarized in the horizontal direction, and the dual antenna feeding paths are independent, ensuring excellent isolation of the dual-frequency ports, and the dual antennas can be designed discretely and combined.

[0025] 7. The mutually coupled improved microwave millimeter-wave co-aperture antenna based on electromagnetic bandgap multiplexing provided by the present invention not only realizes the integration of microwave MIMO antenna and millimeter-wave phased array antenna, but also overcomes the common problem of "double antennas restraining each other" existing in the existing microwave millimeter-wave co-aperture antenna design, and achieves the effect of greatly improving microwave MIMO mutual coupling and millimeter-wave gain while obtaining high space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0027] Figure 1a A top view of the overall structure of the antenna of the present invention;

[0028] Figure 1b It is a side view of the overall structure of the antenna of the present invention;

[0029] Figure 1c A top view of a single unit in the millimeter wave antenna array of the present invention;

[0030] Figure 2 This is a microwave frequency band reflection coefficient diagram of the mutually coupled improved microwave / millimeter wave common aperture antenna based on electromagnetic band gap multiplexing of the present invention;

[0031] Figure 3 a is the radiation pattern of the first resonant frequency point in the microwave frequency band of the mutually coupled improved microwave / millimeter wave co-aperture antenna based on electromagnetic band gap multiplexing of the present invention;

[0032] Figure 3 b is the radiation pattern of the microwave / millimeter wave co-aperture antenna with improved mutual coupling based on electromagnetic band gap multiplexing in the second resonant frequency point of the microwave frequency band of the present invention;

[0033] Figure 4 The millimeter wave frequency band port reflection coefficient and array gain diagram of the mutually coupled improved microwave / millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing of the present invention;

[0034] Figure 5 The radiation pattern of the millimeter wave array of the mutually coupled improved microwave / millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing at 28 GHz of the present invention;

[0035] Figure 6 This is a horizontal diagram of the beam scanning of the millimeter wave array of the mutually coupled improved microwave / millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing of the present invention;

[0036] Figure 7This is a dual-band port isolation diagram of the mutually coupled improved microwave / millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing of the present invention.

[0037] Description of reference numerals:

[0038] 1. Top metal structure; 1-1. Rectangular metal patch; 1-2. Long strip groove; 1-3. Ground hole; 1-4. Feed probe; 1-5. Four-unit millimeter wave antenna array; 1-5-1. Small square metal patch; 1-5-2. Slender metal branch; 1-5-3. Metallized via; 2. First dielectric substrate; 3. Metal ground; 3-1. Short groove; 4. Second dielectric substrate; 5. Feed layer metal structure. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] The present invention provides a mutually coupled improved microwave millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing, and its case structure schematic diagram is shown in Figure 1. It is mainly composed of a top metal structure 1, a first dielectric substrate 2, a metal ground 3, a second dielectric substrate 4 and a feeding layer metal structure 5. The feeding layer metal structure 5 is provided with port one, an independent port and port two as shown in Figure 1. The two rectangular metal patches 1-1 in the top metal structure 1 each have a long strip groove 1-2 and a row of evenly distributed grounding holes 1-3, which are excited by signals fed into port one and port two through a feeding probe 1-4, respectively, to form two microwave planar inverted F antenna units, which are microwave unit one and microwave unit two in Figure 1. The eight mushroom-shaped structures located in the middle of the top metal structure 1 constitute a four-unit millimeter wave antenna array 1-5. Each millimeter wave antenna unit structure includes two mushroom-shaped structures (constructed by a small square metal patch 1-5-1, a slender metal branch 1-5-2 and a metalized via 1-5-3). After the signal is fed from an independent port, it is coupled and excited by a short slot located in the metal ground 3. In this common aperture antenna, the long strip slot 1-2 is 0.7λ long in the vertical direction. g -0.75λ g (λ g is the wavelength of the waveguide corresponding to the center frequency of the microwave frequency band), and the width is 0.04λ g -0.06λ g , 0.3λ away from the edge of the rectangular metal patch 1-1 grounded side g -0.35λ g ; In each mushroom-shaped structure, the small square metal patch 1-5-1 is 0.15λ long in the horizontal direction g -0.2λ g , width is 0.08λ g -0.1λg , the length of the slender metal branch 1-5-2 is 0.05λ g -0.07λ g , with a width of 0.015λ g -0.02λ g , the diameter of the metallized via 1-5-3 is 0.013λ g -0.015λ g The distance between each two mushroom-shaped structures is 0.02λ g -0.03λ g .

[0041] According to the above working mechanism analysis and design guidance, the present invention realizes a case for reference. The structure of the mutual coupling improved microwave millimeter wave co-aperture antenna based on electromagnetic bandgap reuse is shown in Figure 1. In the design case, the first dielectric substrate 2 used is F4B plate, and the second dielectric substrate 4 is R04003C plate. The matching and gain simulation results of the co-aperture antenna proposed in the present invention in the microwave frequency band are shown in Figure 1. Figure 2 The 10-dB impedance matching bandwidth in the microwave band is 6.2%, covering 4.79 GHz to 5.1 GHz. In the whole frequency band, the mutual coupling level between the two units is lower than -18.2 dB; when the electromagnetic band gap, i.e., millimeter wave antenna, is not loaded, the mutual coupling at the center frequency will be as high as -9.8 dB. Figure 3 The simulated radiation patterns of the microwave antenna at two resonant frequencies in this case are shown. In order to clearly show the impact of decoupling on the radiation pattern, the microwave antenna without a millimeter-wave antenna (i.e., a non-co-aperture environment) is also simulated in this case. After decoupling, the radiation pattern offset of the planar inverted F antenna is improved to a certain extent, achieving better spatial coverage and significantly reducing cross-polarization. The above results show that the co-aperture antenna design achieves a significant improvement in microwave mutual coupling.

[0042] In this case, the simulation results of the independent port reflection coefficient and array gain of the common aperture antenna in the millimeter wave frequency band are as follows: Figure 4 The bandwidth of the millimeter wave band ranges from 25.9 GHz to 29.8 GHz, which meets the requirements of applications working in the n257 band (i.e., 26.5 GHz to 29.5 GHz). The mutual coupling between units is lower than -17 dB, and the antenna array gain within the band is greater than 10.5 dB, showing good array working performance.

[0043] Figure 5 The radiation pattern of the millimeter wave antenna array at the center frequency (28GHz) is shown. The radiation pattern of the antenna is symmetrical and the cross-polarization level is less than -25dB. In addition, by independently feeding the millimeter wave antenna units and adjusting the feeding phase difference, the millimeter wave array can achieve beam scanning. Figure 6 As shown, in this case, the millimeter wave antenna array can support ±40° beam scanning.

[0044] Figure 7 The simulation results of isolation between the microwave band feeding port and the millimeter wave band port of the co-aperture antenna in this case are shown. In the microwave band, the isolation of the dual-band ports is greater than 50dB, and in the millimeter wave band, the isolation of the dual-band ports is greater than 33dB. The relevant results show that the microwave antenna and millimeter wave array work independently and the radiation interference is weak.

[0045] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing, characterized in that: The invention comprises a top metal structure (1), a first dielectric substrate (2), a metal ground (3), a second dielectric substrate (4) and a feed layer metal structure (5) which are arranged in sequence from top to bottom; the top metal structure comprises two rectangular metal patches (1-1) which are arranged symmetrically on the left and right, and a row of four-unit millimeter wave antenna arrays (1-5) which are arranged between the two rectangular metal patches (1-1).

2. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 1 is characterized in that: A row of grounding holes (1-3), long strip grooves (1-2) and feeding probes (1-4) are provided on each of the two rectangular metal patches (1-1).

3. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 2, characterized in that: The grounding hole (1-3), the long strip groove (1-2) and the feeding probe (1-4) are arranged in sequence from the inside to the outside of the rectangular metal patch (1-1).

4. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 3 is characterized in that: The feeding probe (1-4) passes downward through the first dielectric substrate (2), the metal ground (3), and the second dielectric substrate (4), and the bottom of the feeding probe (1-4) is connected to the feeding layer metal structure (5).

5. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 4, characterized in that: Each unit millimeter wave antenna comprises two small square metal patches (1-5-1) symmetrically arranged front and back, each small square metal patch (1-5-1) is provided with slender metal branches (1-5-2) on both sides, and each small square metal patch (1-5-1) is provided with a metallized via (1-5-3).

6. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 5, characterized in that: The metal ground (3) is provided with a short groove (3-1) in an area corresponding to the gap between the two small square metal patches (1-5-1).

7. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 2, characterized in that: A long strip groove (1-2) and a row of evenly distributed grounding holes (1-3) on two rectangular metal patches (1-1) in the top metal structure (1) are excited by signals fed into them from port one and port two via a feeding probe (1-4), respectively, to form two microwave planar inverted F antenna units.

8. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 6, characterized in that: A row of four-unit millimeter wave antenna arrays (1-5) located in the middle of the top metal structure (1) is composed of eight mushroom-shaped structures. Each millimeter wave antenna array (1-5) is composed of two mushroom-shaped structures, which are composed of small square metal patches (1-5-1), slender metal branches (1-5-2) and metallized vias (1-5-3). After signals are fed into the independent ports, they are coupled and excited through short slots (3-1) located in the metal ground (3).

9. The mutually coupled improved microwave millimeter wave common aperture antenna based on electromagnetic bandgap multiplexing according to claim 6, characterized in that: The length of the long strip groove (1-2) in the vertical direction is 0.7λ g -0.75λ g ,λ g is the wavelength of the waveguide corresponding to the center frequency of the microwave frequency band, and its width is 0.04λ g -0.06λ g , 0.3λ away from the edge of the grounded side of the rectangular metal patch (1-1) g -0.35λ g ; In each mushroom-shaped structure, the small square metal patch (1-5-1) is 0.15λ long in the horizontal direction g -0.2λ g , width is 0.08λ g -0.1λ g , the length of the slender metal branch (1-5-2) is 0.05λ g -0.07λ g , with a width of 0.015λ g -0.02λ g , the diameter of the metallized via (1-5-3) is 0.013λ g -0.015λ g The distance between each two mushroom-shaped structures is 0.02λ g -0.03λ g .

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