Broadband vertical coupling filter

Abstract

The invention belongs to the technical field of microwaves, and discloses a broadband vertical coupling filter which comprises a first metal grounding plate and a second metal grounding plate, a first resonator layer, a second resonator layer and a third resonator layer are sequentially arranged between the first metal grounding plate and the second metal grounding plate, a plurality of metal columns are distributed on the second metal grounding plate, and the metal columns are arranged on the second metal grounding plate. The top of the metal column is connected with the metal patch, all the metal patches and the metal column jointly define a quasi-closed resonant cavity, the first resonator layer comprises a first resonator, the first resonator layer, the second resonator layer and the third resonator layer are located in the quasi-closed resonant cavity, and the second resonator is connected to the first resonator layer and the third resonator layer. According to the invention, low loss and miniaturization of the broadband filter can be realized.

Description

Technical Field

[0001] The invention belongs to the field of microwave technology, and in particular relates to a broadband vertical coupling filter. Background Art

[0002] In recent years, research on artificial magnetic conductors (AMCs) in the millimeter-wave band has garnered significant attention. Their core consists of periodically arranged EBG (electromagnetic band gap) structural units. When placed parallel to an ideal conductor, they form a contactless electromagnetic shielding structure. This structure stands out for its wide electromagnetic bandgap, low loss, and self-encapsulation. Based on their structure, they can be categorized into ridge-gap waveguides, slot-gap waveguides, and suspended microstrip line-gap waveguides. Among these, printed ridge-gap waveguides (PRGs) have become a research hotspot due to their compact size, ease of integration, and air-transmission properties.

[0003] In the filter field, despite continuous technological innovation and a proliferation of design solutions, the surge in demand for wireless communications, the iterative upgrades of communication technologies, and the widespread adoption of IoT devices have made increasing the integration of microwave components a key development direction. This places extremely high demands on miniaturization in the design of new filters. In current research, vertical coupling technology is often used to achieve filter miniaturization. However, this technology still has many shortcomings, such as insufficient out-of-band suppression depth, narrow stopband width, high loss, and the need for further miniaturization. Summary of the Invention

[0004] In order to achieve the above-mentioned purpose, the present application provides a broadband vertical coupling filter, which introduces two weak coupling paths on the basis of traditional vertical coupling to construct a quasi-closed resonant cavity. The broadband vertical coupling filter of the present application can achieve low loss and miniaturization of the broadband filter.

[0005] In order to achieve the above objectives, this application is implemented through the following technical solutions:

[0006] The present application is a broadband vertically coupled filter, comprising a first metal ground plate and a second metal ground plate arranged horizontally, wherein a first resonator layer, a second resonator layer and a third resonator layer are arranged in sequence from top to bottom between the first metal ground plate and the second metal ground plate, and a plurality of EBG units are arranged between the second metal ground plate and the first resonator layer. A quasi-closed resonant cavity is formed between the second metal ground plate and the first resonator layer through a plurality of periodically arranged EBG units, thereby forming an electromagnetic shielding effect, confining energy in the quasi-closed resonant cavity, and improving the no-load quality factor. The second resonator layer is respectively connected to the first resonator layer and the third resonator layer, and the first resonator layer, the second resonator layer and the third resonator layer are located in the quasi-closed resonant cavity, realizing vertical electrical and energy coupling between the first resonator layer, the second resonator layer and the third resonator layer.

[0007] A further improvement of the present application is that metal patches are periodically and vertically arranged on the first resonator layer, and a number of metal columns corresponding to the metal patches are periodically arranged on the upper surface of the second metal ground plate, and each corresponding metal column is connected to the metal patch to form an EGB unit.

[0008] A further improvement of the present application is that a pair of symmetrically arranged first resonators are arranged in the first resonator layer, each first resonator is connected to a microstrip line, and the quasi-closed resonant cavity has a first opening and a second opening, one of the microstrip lines extends from the first opening and serves as the input end Port1, and the other microstrip line extends from the second opening and serves as the output end Port2, thereby realizing the feeding of electromagnetic signals.

[0009] A further improvement of the present application is that the microstrip line adopts a multi-section stepped impedance microstrip line, including a high impedance section arranged in a trapezoidal shape, an intermediate impedance section arranged in a rectangular shape, and a low impedance section arranged in a trapezoidal shape. A window is opened in the intermediate impedance section between the high impedance section and the intermediate impedance section arranged in a rectangular shape. The intermediate impedance section and the low impedance section arranged in a trapezoidal shape are interconnected. The microstrip line is connected to the first resonator through the low impedance section, thereby realizing a smooth transition between the microstrip line and the quasi-sealed resonant cavity.

[0010] A further improvement of the present application is that: each first resonator is a quarter-wavelength asymmetric hairpin resonator, the first resonator includes a first short arm and a first long arm, realizing a differentiated coupling function, the first short arm and the first long arm of the same first resonator are parallel to each other and one end of the first short arm is connected to one end of the first long arm, the first long arms of two symmetrical first resonators are adjacent and spaced apart, and the first short arm of each first resonator is respectively connected to a corresponding microstrip line.

[0011] A further improvement of the present application is that: a pair of symmetrically arranged second resonators are arranged in the second resonator layer, the second resonator is a quarter-wavelength asymmetric hairpin resonator, the second resonator includes a second short arm and a second long arm, the second short arm and the second long arm of the same second resonator are parallel to each other and one end of the second short arm is connected to one end of the second long arm, the second short arms of the two second resonators are adjacent and spaced apart, and lateral coupling resonance is formed between the second short arms of the two symmetrically arranged second resonators to realize multi-path transmission of the signal.

[0012] A further improvement of the present application is that a third resonator is arranged in the third resonator layer, the third resonator layer is a half-wavelength resonator with folded step impedance, the third resonator includes two third short arms located in the middle and two third long arms located on both sides, one end of the two parallel third short arms is respectively connected to the adjacent third long arm and the two adjacent third short arms are connected, and the two third long arms and the two third short arms are arranged in parallel.

[0013] A further improvement of the present application is that: a first square patch resonator is adjacently arranged at the end of each first short arm, the first square patch resonator is connected to the second long arm of the second resonator through a first metal connecting column, a second square patch resonator is adjacently arranged at each third long arm of the third resonator, the second square patch resonator is connected to the second long arm of the second resonator through a second metal connecting column, in the first resonator layer, the two symmetrical first resonators are laterally weakly coupled to resonate, and at the same time, the two symmetrical first resonators and the first square patch resonator are laterally coupled to resonate, the first square patch resonator is vertically coupled with the second resonator through the first metal connecting column, and the electromagnetic energy in the first resonator layer is transferred to the second resonator layer, in the second resonator layer, a laterally coupled resonance is formed between the two symmetrically arranged second resonators, and at the same time, the second resonator and the second square patch resonator are laterally coupled to resonate, the second square patch resonator is vertically coupled to the third resonator through the second metal connecting column, and the electromagnetic energy in the second resonator layer is transferred to the third resonator layer.

[0014] The beneficial effects of this application are:

[0015] This application innovatively introduces two weak coupling paths based on traditional vertical coupling through the design of the first resonator layer, the second resonator layer and the third resonator layer.

[0016] This application uses a periodically distributed EBG unit structure to confine energy within a quasi-closed electromagnetic cavity, effectively reducing energy loss. This application constructs a quasi-closed resonant cavity, and combined with the design of a multi-section stepped impedance microstrip line, can effectively reduce electromagnetic leakage and significantly improve the no-load quality factor Qe.

[0017] By precisely controlling the coupling strength of the weakly coupled resonant path, the present application can effectively adjust the frequency position of the transmission zero point, thereby significantly improving the out-of-band suppression performance and frequency selectivity of the filter. At the same time, by increasing the number of vertically coupled resonator layers, the distribution of the resonators in the vertical direction is further optimized, which greatly reduces the size of the filter and the volume of the horizontal space. The overall size is compact and easy to process and manufacture. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of the broadband vertically coupled filter of the present application.

[0019] Figure 2 This is a top-down perspective view of the broadband vertically coupled filter of the present application.

[0020] Figure 3 It is a schematic diagram of the structure of a single EGB unit of this application.

[0021] Figure 4 This is a top view of the quasi-sealed resonant cavity in the first resonator layer of the present application.

[0022] Figure 5 It is a schematic diagram of the microstrip line of this application.

[0023] Figure 6 It is a top view of the structure in the first resonator layer of this application.

[0024] Figure 7 4 is a top view of the second resonator in the second resonator layer of the present application.

[0025] Figure 8 1 is a top view of the third resonator and the second square patch resonator in the third resonator layer of the present application.

[0026] Figure 9 This is a parameter simulation waveform diagram of the broadband vertical coupling filter design of this application.

[0027] Among them, G1-first metal ground plane; G2-second metal ground plane; 10-first resonator layer; 11-second resonator layer; 12-third resonator layer; 1-metal column; 2-metal patch; 3-quasi-closed resonant cavity; 31-first opening; 32-second opening; 4-first resonator; 5-microstrip line; 51-high impedance section; 52-middle impedance section; 53-low impedance section; 521-window; 6-second resonator; 7-third resonator; RL1-first square patch resonator; RL3-second square patch resonator; 91-first metal connecting column; 92-second metal connecting column. DETAILED DESCRIPTION

[0028] The following diagrams illustrate embodiments of the present application. For clarity, many practical details will be included in the following description. However, it should be understood that these practical details are not intended to limit the present application. In other words, in some embodiments of the present application, these practical details are not essential. Furthermore, to simplify the drawings, some conventional structures and components are depicted in the drawings in a simplified schematic manner.

[0029] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal connections between two components; they can refer to wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0032] like Figure 1-Figure 3 As shown, the present application discloses a broadband vertically coupled filter, including a first metal ground plate G1 and a second metal ground plate G2 arranged horizontally, wherein a first resonator layer 10, a second resonator layer 11 and a third resonator layer 12 are arranged in sequence from top to bottom between the first metal ground plate G1 and the second metal ground plate G2, and the second resonator layer 11 is connected to the first resonator layer 10 and the third resonator layer 12 respectively, and the first resonator layer 10, the second resonator layer 11 and the third resonator layer 12 are located in the quasi-closed resonant cavity 3 to realize vertical electrical and energy coupling between the first resonator layer 10, the second resonator layer 11 and the third resonator layer 12, thereby generating more resonance points to realize a wider bandwidth filter design, and generating more transmission zeros to expand the stopband range.

[0033] Metal patches 2 are periodically and vertically arranged on the first resonator layer 10, and a number of metal columns 1 corresponding to the metal patches 2 are periodically and vertically arranged on the upper surface of the second metal ground plate G2. Each corresponding metal column 1 is connected to the metal patch 2 to form a mushroom-shaped EGB unit structure.

[0034] like Figure 4 As shown, several EBG units are disposed between the second metal ground plane G2 and the first resonator layer 10. These periodically arranged EBG units together form a quasi-sealed resonant cavity 3, effectively suppressing the rapid attenuation of energy caused by outward electromagnetic field radiation. Furthermore, to achieve broadband filtering in the millimeter-wave band, the electromagnetic bandgap can be controlled by adjusting the lateral width W and longitudinal length L of the quasi-sealed resonant cavity 3. The electromagnetic shielding effect created by the two rows of mushroom-shaped EBG units surrounding the quasi-sealed resonant cavity 3 efficiently confines energy within the quasi-sealed resonant cavity 3, significantly improving the unloaded quality factor Qe.

[0035] like Figure 1 and Figure 4 As shown, a pair of symmetrically arranged first resonators 4 are provided in the first resonator layer 10, each of the first resonators 4 is connected to a microstrip line 5, and the quasi-closed resonant cavity 3 has a first opening 31 and a second opening 32, wherein one of the microstrip lines 5 extends from the first opening 31 and serves as an input end Port1, and the other microstrip line 5 extends from the second opening 32 and serves as an output end Port2, thereby realizing the feeding of electromagnetic signals through the microstrip-gap waveguide structure.

[0036] like Figure 5 As shown, the microstrip line 5 adopts a multi-section stepped impedance microstrip line, including a high impedance section 51 arranged in a trapezoidal shape, an intermediate impedance section 52 arranged in a rectangular shape, and a low impedance section 53 arranged in a trapezoidal shape. The high impedance section 51 and the intermediate impedance section 52 arranged in a rectangular shape are connected to each other, and the intermediate impedance section 52 and the low impedance section 53 arranged in a trapezoidal shape are connected to each other. The microstrip line 5 is connected to the first resonator 4 through the low impedance section 53. This structure is based on microstrip-gap waveguide conversion to achieve a smooth transition between the microstrip line 5 and the quasi-sealed resonant cavity 3. A window 521 is provided on the intermediate impedance section 52 to further optimize the electromagnetic coupling characteristics.

[0037] like Figure 6As shown, each first resonator 4 is a quarter-wavelength asymmetric hairpin resonator. The wavelength refers to the operating wavelength of the first resonator 4. The first resonator 4 includes a first short arm and a first long arm to achieve a differentiated coupling function. The first short arm and the first long arm of the same first resonator 4 are parallel to each other, and one end of the first short arm is connected to one end of the first long arm. The first long arms of two symmetrical first resonators 4 are adjacent and spaced apart. The first short arm of each first resonator 4 is respectively connected to a corresponding microstrip line 5.

[0038] like Figure 7 As shown, a pair of symmetrically arranged second resonators 6 are provided in the second resonator layer 11. The second resonator 6 is a quarter-wavelength asymmetric hairpin resonator. The second resonator 6 includes a second short arm and a second long arm. The second short arm and the second long arm of the same second resonator 6 are parallel to each other, and one end of the second short arm is connected to one end of the second long arm. The second short arms of the two second resonators 6 are adjacent and spaced apart. Lateral coupling resonance is formed between the second short arms of the two symmetrically arranged second resonators 6 to achieve multipath transmission of the signal. The wavelength here refers to the operating wavelength of the second resonator 6.

[0039] like Figure 8 As shown, a third resonator 7 is arranged in the third resonator layer 12. The third resonator layer 12 is a half-wavelength resonator with folded step impedance. The third resonator 7 includes two third short arms located in the middle and two third long arms located on both sides. One end of the two parallel third short arms is respectively connected to the adjacent third long arms and the two adjacent third short arms are connected. The two third long arms and the two third short arms are arranged in parallel. The wavelength here refers to the operating wavelength of the third resonator 7.

[0040] In order to realize the electrical connection and signal coupling between the first resonator layer 10, the second resonator layer 11 and the third resonator layer 12, as shown in FIG. Figure 1 and Figure 6 As shown, in the first resonator layer 10, a first square patch resonator RL1 is adjacently arranged at the end of each of the first short arms, and the first square patch resonator RL1 is connected to the second long arm of the second resonator 6 through a first metal connecting column 91. A second square patch resonator RL3 is adjacently arranged at each third long arm of the third resonator 7, and the second square patch resonator RL3 is connected to the second long arm of the second resonator 6 through a second metal connecting column 92.

[0041] Through the above arrangement, in the first resonator layer 10, the two symmetrical first resonators 4 are laterally weakly coupled to resonate, and at the same time, the two symmetrical first resonators 4 and the first square patch resonator RL1 are laterally coupled to resonate. The first square patch resonator RL1 is vertically coupled with the second resonator 6 through the first metal connecting column 91, and the electromagnetic energy in the first resonator layer 10 is transferred to the second resonator layer 11. In the second resonator layer 11, a lateral coupling resonance is formed between the two symmetrically arranged second resonators 6. At the same time, the second resonator 6 and the second square patch resonator RL3 are laterally coupled to resonate. The second square patch resonator RL3 is vertically coupled with the third resonator 7 through the second metal connecting column 92, and the electromagnetic energy in the second resonator layer 11 is transferred to the third resonator layer 12. The filter structure meets the high selectivity and miniaturization requirements of the millimeter wave filter through three-dimensional spatial layout and multi-form coupling design.

[0042] like Figure 6 As shown, the short side length of the high impedance section in the microstrip line is The width of the middle impedance segment, that is, the length of the long side of the high impedance segment, is , the long side length of the low impedance segment is , the length of the first long arm of the first resonator is , the width of the first resonator is , the length of the first short arm of the first resonator is , the gap width between the two first resonators is .

[0043] like Figure 7 As shown, the critical dimensions involved in the second resonator are 、 、 、 、 、 and the gap width between the two second resonators .

[0044] like Figure 8 As shown, the critical dimensions involved in the third resonator are 、 、 、 、 、 and the gap width between the two third short arms of the third resonator .

[0045] For each of the above dimensions, the values ​​can be shown in Table 1:

[0046] Table 1

[0047] By simulating the broadband vertically coupled filter designed with the above dimensions, we can get the following: Figure 9 The simulation results are shown in Figure 2. The simulation results show that its passband range covers 31.95GHz-39.1GHz, with a center frequency of 35.53GHz, a -3dB bandwidth of 7.15GHz, and a corresponding fractional bandwidth of 20.1%, achieving wideband signal transmission capabilities. At the same time, the filter has extremely low insertion loss, with a minimum passband insertion loss of only 0.15dB. Within the 32.78GHz to 38.28GHz frequency band, the maximum insertion loss is controlled within 0.18dB, effectively ensuring efficient and low-loss signal transmission within the passband.

[0048] The filter exhibits excellent selectivity on both sides of the band. Figure 9 The S21 parameter decreases at a rate of 27.6 dB / GHz on the left side of the mid-band and 26.3 dB / GHz on the right side. This result reflects the filter's ability to quickly suppress out-of-band signals at the passband boundary, forming a steep transition band characteristic.

[0049] In terms of stopband performance, the filter exhibits excellent wide-stopband rejection. At 31 GHz, it achieves a stopband rejection of 38.76 dB; across the 5-25.2 GHz and 45.4-70 GHz widebands, the rejection exceeds 25 dB. These performance indicators demonstrate that this broadband vertically coupled filter achieves high levels of passband transmission efficiency and stopband rejection.

[0050] The broadband vertical coupling filter provided in the embodiment of the present application innovatively introduces two weak coupling paths on the basis of traditional vertical coupling through the design of the first resonator layer, the second resonator layer and the third resonator layer, constructs a multi-dimensional coupling network, reduces the volume of the horizontal space, and has a compact overall size, which is easy to process and manufacture. At the same time, the broadband vertical coupling filter has a high degree of compatibility and can easily be integrated with other microwave and millimeter wave circuit systems. In addition, a quasi-sealed resonant cavity is constructed through a periodically distributed EBG unit structure. Combined with the design of a multi-section stepped impedance microstrip line, it can effectively reduce electromagnetic leakage and significantly improve the unloaded quality factor Qe. The resonance point can be determined by the length and width of the rectangular quasi-sealed resonant cavity, the design of each dimension on each resonator, and the dimensional parameters of the multi-section stepped impedance microstrip line.

[0051] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A broadband vertically coupled filter comprising a first metal ground plate (G1) and a second metal ground plate (G2) arranged horizontally, characterized in that: A first resonator layer (10), a second resonator layer (11) and a third resonator layer (12) are sequentially arranged between the first metal ground plate (G1) and the second metal ground plate (G2) from top to bottom; a plurality of EBG units are arranged between the second metal ground plate (G2) and the first resonator layer (10); a quasi-sealed resonant cavity (3) is formed between the second metal ground plate (G2) and the first resonator layer (10) through a plurality of periodically arranged EBG units, thereby forming an electromagnetic shielding effect, confining energy within the quasi-sealed resonant cavity (3), and improving the no-load quality factor; the second resonator layer (11) is respectively connected to the first resonator layer (10) and the third resonator layer (12); the first resonator layer (10), the second resonator layer (11) and the third resonator layer (12) are located within the quasi-sealed resonant cavity (3), and realize electrical and energy vertical coupling between the first resonator layer (10), the second resonator layer (11) and the third resonator layer (12).

2. A broadband vertically coupled filter according to claim 1, characterized in that: Metal patches (2) are periodically arranged on the first resonator layer (10), and a plurality of metal columns (1) corresponding to the metal patches (2) are periodically arranged on the upper surface of the second metal ground plate (G2), and each corresponding metal column (1) is connected to the metal patch (2) to form an EGB unit.

3. The broadband vertically coupled filter according to claim 1, wherein: A pair of symmetrically arranged first resonators (4) are provided in the first resonator layer (10), each of the first resonators (4) is connected to a microstrip line (5), and the quasi-sealed resonant cavity (3) has a first opening (31) and a second opening (32), wherein one of the microstrip lines (5) extends from the first opening (31) and serves as an input end Port1, and the other microstrip line (5) extends from the second opening (32) and serves as an output end Port2, thereby realizing the feeding of electromagnetic signals.

4. The broadband vertically coupled filter according to claim 3, wherein: The microstrip line (5) adopts a multi-section stepped impedance microstrip line, including a high impedance section (51) arranged in a trapezoidal shape, an intermediate impedance section (52) arranged in a rectangular shape, and a low impedance section (53) arranged in a trapezoidal shape. A window (521) is provided on the intermediate impedance section (52) between the high impedance section (51) and the intermediate impedance section (52) arranged in a rectangular shape. The intermediate impedance section (52) and the low impedance section (53) arranged in a trapezoidal shape are connected to each other. The microstrip line (5) is connected to the first resonator (4) through the low impedance section (53), thereby achieving a smooth transition between the microstrip line (5) and the quasi-sealed resonant cavity (3).

5. The broadband vertically coupled filter according to claim 4, wherein: Each first resonator (4) is a quarter-wavelength asymmetric hairpin resonator. The first resonator (4) includes a first short arm and a first long arm to realize a differentiated coupling function. The first short arm and the first long arm of the same first resonator (4) are parallel to each other and one end of the first short arm is connected to one end of the first long arm. The first long arms of two symmetrical first resonators (4) are adjacent and spaced apart. The first short arm of each first resonator (4) is respectively connected to a corresponding microstrip line (5).

6. The broadband vertically coupled filter according to claim 5, characterized in that: A pair of symmetrically arranged second resonators (6) are provided in the second resonator layer (11). The second resonator (6) is a quarter-wavelength asymmetric hairpin resonator. The second resonator (6) includes a second short arm and a second long arm. The second short arm and the second long arm of the same second resonator (6) are parallel to each other, and one end of the second short arm is connected to one end of the second long arm. The second short arms of the two second resonators (6) are adjacent and spaced apart. A lateral coupling resonance is formed between the second short arms of the two symmetrically arranged second resonators (6), thereby realizing multi-path transmission of signals.

7. The broadband vertically coupled filter according to claim 6, wherein: A third resonator (7) is arranged in the third resonator layer (12), and the third resonator layer (12) is a half-wavelength resonator with folded step impedance. The third resonator (7) includes two third short arms located in the middle and two third long arms located on both sides, one end of the two parallel third short arms is respectively connected to the adjacent third long arms and the adjacent two third short arms are connected, and the two third long arms and the two third short arms are arranged in parallel.

8. The broadband vertically coupled filter according to claim 7, wherein: A first square patch resonator (RL1) is adjacently arranged at the end of each first short arm, and the first square patch resonator (RL1) is connected to the second long arm of the second resonator (6) through a first metal connecting column (91). A second square patch resonator (RL3) is adjacently arranged at each third long arm of the third resonator (7), and the second square patch resonator (RL3) is connected to the second long arm of the second resonator (6) through a second metal connecting column (92). In the first resonator layer (10), two symmetrical first resonators (4) are laterally weakly coupled and resonate with each other, and at the same time, the two symmetrical first resonators (4) and the first square patch resonator (R The first square patch resonator (RL1) is vertically coupled with the second resonator (6) through the first metal connecting column (91), and the electromagnetic energy in the first resonator layer (10) is transferred to the second resonator layer (11). In the second resonator layer (11), a lateral coupling resonance is formed between the two symmetrically arranged second resonators (6). At the same time, a lateral coupling resonance is formed between the second resonator (6) and the second square patch resonator (RL3). The second square patch resonator (RL3) is vertically coupled with the third resonator (7) through the second metal connecting column (92), and the electromagnetic energy in the second resonator layer (11) is transferred to the third resonator layer (12).

Images