Miniaturized shielding type substrate integrated waveguide filter for millimeter wave communication

Abstract

The invention provides a miniaturized shielding type substrate integrated waveguide filter for millimeter wave communication, which comprises a filtering resonance structure, a dielectric substrate, a top metal layer, a bottom metal layer and an EMSIW arc resonant cavity, the interstage coupling structure is arranged on the top metal layer between the adjacent resonant cavities; the feed conversion structure is arranged on the top metal layer; the bottom grounding shielding structure is arranged at the bottom of the bottom metal layer; and the shielding structure is packaged at the top and is fixedly connected in a press fit manner, so that the filter forms an integral laminated structure in sequence from top to bottom in the longitudinal direction to reduce radiation loss. An EMSIW arc resonant cavity structure is adopted, the structure is compact and easy to integrate, the width is smaller than half wavelength, the size of the filter can be effectively reduced, and the filter is suitable for a millimeter wave large-scale MIMO antenna array; meanwhile, steep out-of-band rejection is obtained through the four-order resonance structure, and the high rejection requirement of a 5G communication system for out-of-band interference can be met.

Description

Technical Field

[0001] This invention relates to the field of microwave radio frequency technology, and more specifically to a miniaturized shielded substrate integrated waveguide filter for millimeter-wave communication. Background Technology

[0002] With the rapid development of 5G communication systems, radio frequency front-end circuits are placing higher demands on filter performance, especially on miniaturized, low-loss, and highly selective filters. In planar massive MIMO antenna arrays, filter dimensions must meet half-wavelength spacing constraints to maintain array compactness.

[0003] Traditional microstrip filters, while simple in structure, suffer from high losses and low quality factors at high frequencies. Ordinary SIW filters, despite their low losses and high quality factors, are large in size, making them unsuitable for high-density array integration. In recent years, half-mode SIW and quarter-mode SIW structures have been proposed to reduce size, but these still present challenges such as structural complexity, high radiation losses, and high integration difficulty. Especially for fourth-order and higher-order filters, maintaining low insertion loss and high selectivity while achieving high integration remains a significant technical challenge.

[0004] Therefore, there is an urgent need for a compact, high-performance, and easily integrated radio frequency filter to meet the compact layout and high-performance requirements of large-scale MIMO arrays in 5G millimeter-wave communication systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a miniaturized shielded substrate integrated waveguide filter for millimeter-wave communication, thereby resolving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides a miniaturized shielded substrate integrated waveguide filter for millimeter-wave communication, comprising: A filter resonant structure includes a dielectric substrate, a top metal layer disposed on the upper surface of the dielectric substrate, a bottom metal layer disposed on the lower surface of the dielectric substrate, and four EMSIW arc-shaped resonant cavities respectively formed in the top metal layer, the dielectric substrate, and the bottom metal layer; an interstage coupling structure disposed on the top metal layer between adjacent resonant cavities, including a first inductive coupling window, a second inductive coupling window, and a third inductive coupling window, for achieving inductive magnetic coupling between adjacent resonant cavities, and controlling the bandwidth and frequency response characteristics of the filter by adjusting the coupling strength; and a power supply conversion structure disposed on the top metal layer, including an input micro-channel... The filter includes a feed line and an output microstrip feed line for impedance matching and signal transmission between the external circuit and the filter resonant structure. A bottom ground shield structure, located at the bottom of the bottom metal layer, includes multiple metallized vias to enhance structural integrity, reduce radiation loss, and minimize interference with adjacent circuits. A top encapsulation shield structure includes a metal structural component positioned above the top metal layer and fixedly connected by pressing. This allows the filter to form a vertically integrated stacked structure from top to bottom, consisting of a metal block, a top metal layer, a dielectric substrate, and a bottom metal layer, thereby reducing radiation loss from the open structure filter.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs an EMSIW arc-shaped resonant cavity structure, which is compact and easy to integrate. Its width is less than half a wavelength, effectively reducing filter size and making it suitable for millimeter-wave massive MIMO antenna arrays. The overall structure is simple, implemented using a single-layer PCB process, eliminating the need for multi-layer stacking or complex transition structures, resulting in low manufacturing costs and suitability for mass production. Simultaneously, a steep out-of-band rejection is achieved through a fourth-order resonant structure, providing excellent frequency selectivity and meeting the high out-of-band interference suppression requirements of 5G communication systems. This makes it suitable for operation in the front-end circuitry of millimeter-wave massive MIMO communication systems. The addition of metallized vias at the bottom and metallized pressure blocks at the top effectively enhances structural integrity, reduces energy leakage, and provides low radiation loss and high shielding characteristics. Furthermore, the filter structure is open and highly compatible, facilitating integration with antennas, power amplifiers, and other RF modules, making it suitable for system-level packaging and integrated design. Attached Figure Description

[0008] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 This is a three-dimensional structural schematic diagram of a fourth-order 1 / 8 mode circular arc SIW filter proposed in one embodiment of the present invention; Figure 2This is a top-view perspective view of the fourth-order 1 / 8 mode circular arc SIW filter proposed in one embodiment of the present invention. Figure 3 This is a schematic diagram of the simulation results of the S-parameter amplitude of the fourth-order 1 / 8 mode circular arc SIW filter proposed in one embodiment of the present invention.

[0009] Figure label: 110-First resonant cavity, 120-Second resonant cavity, 130-Third resonant cavity, 140-Fourth resonant cavity, 150-First inductive coupling window, 160-Second inductive coupling window, 170-Third inductive coupling window, 180-Metallized via, 190-Metal structural component, 200-Etched slot, 210-First arc-shaped etched slot, 220-Second arc-shaped etched slot, 230-Third arc-shaped etched slot, 240-Metal-air cavity, 250-Metal-air cavity, 260-Metal-air cavity, 270-Input microstrip feed line, 280-Output microstrip feed line, 290-Dielectric substrate, 300-Top metal layer, 310-Bottom metal layer. Detailed Implementation

[0010] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0011] The present invention will be further described in detail below with reference to the accompanying drawings, but this is not intended to limit the scope of the invention.

[0012] like Figures 1-3 As shown, the present invention proposes a miniaturized shielded substrate integrated waveguide filter for millimeter-wave communication, comprising: a filter resonant structure, an interstage coupling structure, a feed conversion structure, a bottom grounding shield structure, and a top encapsulation shield structure.

[0013] It is understandable that the filter resonant structure, as the functional carrier of the filter, adopts a single-layer EMSIW arc-shaped resonant cavity to achieve the goal of filter miniaturization.

[0014] Interstage coupling structure is set between adjacent resonant cavities in the filter resonant structure. Inductive magnetic coupling is achieved through an arc-shaped opening. The bandwidth and frequency response characteristics of the filter can be controlled by adjusting the width and position of the opening.

[0015] The power supply conversion structure is located on both sides of the filter resonant structure. It achieves a compact transition connection with the EMSIW arc-shaped resonator through etched grooves, meeting the requirements of broadband impedance matching. Its purpose is to facilitate the connection and integration with other external millimeter-wave communication modules or circuits.

[0016] The bottom grounding shield structure is located below the filter resonant structure to enhance structural integrity, reduce radiation loss, and minimize interference to nearby circuits.

[0017] The top-encapsulated shielding structure is located above the filter resonant structure to reduce radiation loss generated by the open structure filter, improve the isolation between active circuits in various parts of the millimeter-wave front-end, and enhance the heat dissipation capability of the overall front-end device.

[0018] It should be noted that the above components are spatially stacked and electrically coordinated to form a fourth-order bandpass filter with miniaturized, low-loss, and highly selective characteristics.

[0019] Because existing ordinary substrate integrated waveguide filters are large in size, they are difficult to meet the integration requirements of high-density arrays. Furthermore, half-mode substrate integrated waveguides and quarter-mode substrate integrated waveguide structures still have problems such as high radiation loss and high integration difficulty.

[0020] Based on this, in this embodiment, the proposed filter resonant structure includes a dielectric substrate 290, a top metal layer 300, a bottom metal layer 310, and four EMSIW arc-shaped resonant cavities formed in the top metal layer 300, the dielectric substrate 290, and the bottom metal layer 310. The top metal layer 300, the dielectric substrate 290, and the bottom metal layer 310 are stacked sequentially. Specifically, the top metal layer 300 is disposed on the upper surface of the dielectric substrate 290, and the bottom metal layer 310 is disposed on the lower surface of the dielectric substrate 290; the three are stacked sequentially.

[0021] Furthermore, the dielectric substrate 290 uses Rogers 5880 high-frequency board material with a thickness of 0.127 mm, and the top metal layer 300 and the bottom metal layer 310 are both 0.035 mm thick.

[0022] Furthermore, the four EMSIW arc-shaped resonant cavities are arranged sequentially according to the signal transmission path, namely the first resonant cavity 110, the second resonant cavity 120, the third resonant cavity 130 and the fourth resonant cavity 140, thus forming a fourth-order bandpass filter.

[0023] Based on the above technical concept, it should be noted that the filter resonant structure is obtained by cutting the arc-shaped substrate integrated waveguide resonator three times along its axis of symmetry using miniaturization technology. Specifically, each EMSIW arc-shaped resonant cavity (one-eighth mode substrate integrated waveguide arc-shaped resonant cavity) is enclosed by multiple arc-shaped metallized vias 180 penetrating the top metal layer 300, the dielectric substrate 290, and the bottom metal layer 310. Four symmetrical one-eighth mode substrate integrated waveguide arc-shaped resonant cavities are obtained by cutting the half-mode substrate integrated waveguide arc-shaped resonant cavities. Among them, an etched slit 200 is provided at the first resonant cavity 110 and the fourth resonant cavity 140 at both ends of the signal transmission path. The etched slit 200 forms the equivalent magnetic wall of the half-mode arc-shaped substrate integrated waveguide resonator and also serves as the equivalent magnetic wall of the first resonant cavity 110 and the fourth resonant cavity 140.

[0024] In this embodiment, as Figure 1 , Figure 2 As shown, the proposed interstage coupling structure is disposed on the top metal layer 300 between adjacent resonant cavities to achieve inductive magnetic coupling between adjacent resonant cavities. Specifically, the interstage coupling structure includes a first inductive coupling window 150, a second inductive coupling window 160, and a third inductive coupling window 170. The first inductive coupling window 150 is formed by a first arc-shaped etched slot 210 on the top metal layer 300 between the first resonant cavity 110 and the second resonant cavity 120; the second inductive coupling window 160 is formed by a second arc-shaped etched slot 220 on the top metal layer 300 between the second resonant cavity 120 and the third resonant cavity 130; and the third inductive coupling window 170 is formed by a third arc-shaped etched slot 230 on the top metal layer 300 between the third resonant cavity 130 and the fourth resonant cavity 140. By adjusting the dimensions of the first inductive coupling window 150, the second inductive coupling window 160, and the third inductive coupling window 170, the coupling coefficient between corresponding adjacent resonant cavities can be precisely controlled, thereby adjusting the bandwidth and frequency response characteristics of the filter.

[0025] In this embodiment, the proposed feed conversion structure includes an input microstrip feed line 270 and an output microstrip feed line 280, both of which are disposed on the top metal layer 300. One end of the input microstrip feed line 270 is used to connect to an external millimeter-wave circuit, and the other end is connected to the first resonant cavity 110 through an etched groove, achieving a compact transition connection and broadband impedance matching from the microstrip line to the EMSIW arc-shaped resonator.

[0026] Furthermore, one end of the output microstrip feed line 280 is used to connect to an external circuit, and the other end is connected to the fourth resonant cavity 140 through an etched groove. It should be noted that the overall structure of the filter is symmetrically arranged about the center of the second arc-shaped etched slot 220, and the input microstrip feed line 270 and the output microstrip feed line 280 are functionally interchangeable.

[0027] In this embodiment, the proposed bottom grounding shield structure is located at the bottom of the bottom metal layer 310, which includes a row of metallized vias 180. The purpose is to enhance structural integrity, reduce radiation loss and reduce interference to adjacent circuits. The metallized vias penetrate the dielectric substrate 290 and connect the top metal layer 300 and the bottom metal layer 310 respectively, and correspond to the regions where the four EMSIW arc-shaped resonant cavities 110, 120, 130 and 140 are located.

[0028] In this embodiment, the proposed top encapsulation shielding structure includes an independently disposed metal structural component 190, which is disposed above the top metal layer 300 and is fixedly connected by pressing, so that the filter forms an overall stacked structure of metal block 190, top metal layer 300, dielectric substrate 290 and bottom metal layer 310 in the vertical direction from top to bottom.

[0029] In specific implementation, the metal structural component 190 is a metal block with its internal area partially hollowed out. Multiple cavities formed by hollowing out its interior form a metal air cavity 240 corresponding to the input microstrip feed line 270 region, a metal air cavity 260 corresponding to the output microstrip feed line 280 region, and a metal air cavity 250 corresponding to the filter core region composed of the first resonant cavity 110, the second resonant cavity 120, the third resonant cavity 130, and the fourth resonant cavity 140.

[0030] It should be noted that the metal structural component 190 proposed in this invention is placed on top of the filter in the form of a pressure block, which can prevent strong electromagnetic energy from leaking from the gaps (200, 210, 220, 230) on the surface of the top metal layer 300, while improving the isolation between the active circuits of each part of the millimeter wave front end and the heat dissipation capability of the overall front end device.

[0031] In one embodiment of the present invention, to verify the electrical performance of the filter, simulation results are verified, as follows: The filter was parametrically modeled and optimized using simulation software. Specifically, while maintaining the basic topological configuration of the filter resonant structure, interstage coupling structure, feed conversion structure, bottom grounding shield structure, and top encapsulation shield structure, the coupling coefficients between the resonant cavities were optimized by adjusting the dimensions of the first inductive coupling window 150, the second inductive coupling window 160, and the third inductive coupling window 170. Simultaneously, the center frequency and passband characteristics of the filter were set by adjusting the dimensions of the etched gap 200 and the physical dimensions of the first resonant cavity 110, the second resonant cavity 120, the third resonant cavity 130, and the fourth resonant cavity 140. After multiple rounds of iterative optimization, the optimal combination of structural parameters that met the design specifications was obtained. Under these optimal parameters, the overall dimensions of the filter (including the metal structural component 190) are 12.07mm × 8.485mm × 5.197mm.

[0032] To further verify the electrical performance of the designed structure, a full-wave electromagnetic simulation analysis was performed on the optimized filter. The S-parameter simulation results are as follows: Figure 3 As shown in Table 1 below, the simulation results show that the filter's center frequency is 26 GHz, the passband range is 24.5 GHz to 27.5 GHz, the relative bandwidth reaches 11.5%, and the insertion loss within the passband is less than 1.05 dB. Specific performance indicators are detailed in Table 1 below.

[0033] category Center frequency passband range relative bandwidth Insertion loss Performance indicators 26GHz 24.5-27.5GHz 11.5% Less than 1.05dB Thus, the simulation results above fully demonstrate that, through the combination of the filter resonant structure, interstage coupling structure, feed conversion structure, bottom grounding shielding structure, and top encapsulation shielding structure proposed in this invention, the miniaturized millimeter-wave filter provided in this embodiment achieves a significant reduction in structure while maintaining excellent frequency selectivity and low insertion loss characteristics. It has good feasibility and electrical performance, and can meet the miniaturized and high-performance application requirements of 5G millimeter-wave communication systems for RF front-end devices.

[0034] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A miniaturized shielded substrate integrated waveguide filter for millimeter-wave communication, characterized in that, include: The filter resonant structure includes a dielectric substrate (290), a top metal layer (300) disposed on the upper surface of the dielectric substrate (290), a bottom metal layer (310) disposed on the lower surface of the dielectric substrate (290), and four EMSIW arc-shaped resonant cavities respectively formed in the top metal layer (300), the dielectric substrate (290) and the bottom metal layer (310); An interstage coupling structure is provided on the top metal layer (300) between adjacent resonant cavities. It includes a first inductive coupling window (150), a second inductive coupling window (160), and a third inductive coupling window (170) to realize inductive magnetic coupling between adjacent resonant cavities and to control the bandwidth and frequency response characteristics of the filter by adjusting the coupling strength. The power conversion structure, disposed on the top metal layer (300), includes an input microstrip feed line (270) and an output microstrip feed line (280), used to achieve impedance matching and signal transmission between the external circuit and the filter resonant structure; A bottom grounding shield structure is provided at the bottom of the bottom metal layer (310) to enhance structural integrity, reduce radiation loss and reduce interference to adjacent circuits; The top encapsulation shielding structure includes a metal structural component (190), which is disposed above the top metal layer (300) and fixedly connected by pressing, so that the filter forms an overall stacked structure of metal block (190), top metal layer (300), dielectric substrate (290) and bottom metal layer (310) in the vertical direction from top to bottom, so as to reduce the radiation loss generated by the open structure filter.

2. The integrated waveguide filter according to claim 1, characterized in that, The bottom grounding shield structure includes multiple metallized vias, each of which is arranged in an arc shape and penetrates the top metal layer (300), the dielectric substrate (290), and the bottom metal layer (310). Each EMSIW arc-shaped resonant cavity is surrounded by multiple metallized vias to form an electromagnetic shielding boundary.

3. The integrated waveguide filter according to claim 2, characterized in that, The multiple metallized vias correspond to the regions where the four EMSIW arc-shaped resonant cavities are located, in order to suppress electromagnetic mode leakage and reduce radiation loss caused by the open structure.

4. The integrated waveguide filter according to claim 1, characterized in that, The filter resonant structure further includes an etched slot (200), which is located at the first resonant cavity (110) and the fourth resonant cavity (140) at both ends of the signal transmission path to form an equivalent magnetic wall of the half-mode arc-shaped substrate integrated waveguide resonator. It also serves as an equivalent magnetic wall of the first resonant cavity (110) and the fourth resonant cavity (140) to define the open boundary of the resonant cavity and adjust the resonant frequency.

5. The integrated waveguide filter according to claim 1, characterized in that, The interstage coupling structure further includes a first arc-shaped etched slot (210), a second arc-shaped etched slot (220), and a third arc-shaped etched slot (230); wherein, the first arc-shaped etched slot (210) is disposed on the top metal layer (300) between the first resonant cavity (110) and the second resonant cavity (120) to form the first inductive coupling window (150); the second arc-shaped etched slot (220) is disposed on the top metal layer (300) between the second resonant cavity (120) and the third resonant cavity (130) to form the second inductive coupling window (160); the third arc-shaped etched slot (230) is disposed on the top metal layer (300) between the third resonant cavity (130) and the fourth resonant cavity (140) to form the third inductive coupling window (170); by adjusting the size of the coupling window, the coupling coefficient between corresponding adjacent resonant cavities is controlled, thereby adjusting the bandwidth and frequency response characteristics of the filter.

6. The integrated waveguide filter according to claim 1, characterized in that, The input microstrip feed line (270) and the output microstrip feed line (280) are both disposed on the top metal layer (300); one end of the input microstrip feed line (270) is connected to an external millimeter-wave circuit, and the other end is connected to the first resonant cavity (110) through an etching groove; one end of the output microstrip feed line (280) is connected to an external circuit, and the other end is connected to the fourth resonant cavity (140) through an etching groove.

7. The integrated waveguide filter according to claim 5, characterized in that, The overall structure of the filter is symmetrically arranged about the center of the second arc-shaped etched slot (220) so that the input microstrip feed line (270) and the output microstrip feed line (280) are functionally interchangeable.

8. The integrated waveguide filter according to claim 1, characterized in that, The interior of the metal structure (190) is hollowed out to form multiple cavities, each cavity corresponding to the area where the input microstrip feed line (270), the output microstrip feed line (280), and the EMSIW arc-shaped resonant cavity are located.

9. The integrated waveguide filter according to claim 1, characterized in that, The four resonant cavities are arranged sequentially according to the signal transmission path to form a fourth-order bandpass filter.

10. The integrated waveguide filter according to claim 2, characterized in that, The dielectric substrate (290) is made of Rogers 5880 high-frequency board with a thickness of 0.127 mm, and the thickness of the top metal layer (300) and the bottom metal layer (310) is 0.035 mm.

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