A three-dimensional multilayer substrate-based siw te20 and tm11 hybrid mode equalizer

Abstract

The application provides a three-dimensional multilayer substrate-based SIW TE20 and TM11 mixed mode equalizer, which comprises a multilayer dielectric substrate, an input / output transition structure, a substrate integrated waveguide, a circular resonant cavity and a bimodal perturbation device, and the physical structure of the equalizer is composed of two layers of dielectric substrates defined as an upper layer of dielectric and a lower layer of dielectric and three layers of metal layers. The application scheme vertically integrates the transmission layer and the resonant layer by using the laminated structure, reduces the planar area of the device, combines the fully enclosed characteristics of the SIW, has the advantages of low loss and high Q value at high frequencies, simultaneously, the degenerate characteristics of the TM11 mode and the symmetric via perturbation are utilized in the circular resonant cavity, two electrically independent resonant peaks are realized in one physical cavity, the frequency interval is adjustable, the complex gain curve can be flexibly fitted, the TM11 mode is excited by using the antisymmetry of the TE20 mode, the unwanted base mode is naturally suppressed, and the response accuracy of the equalizer is improved.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave passive device technology, and in particular to a SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate. Background Technology

[0002] In broadband wireless communication, radar detection, and satellite communication systems, traveling wave tube amplifiers (TWTAs) and solid-state power amplifiers (SSPAs) are core components. However, when these active devices operate over a wide bandwidth, their gain often tilts or fluctuates with frequency (gain ripple), severely affecting the signal integrity of the system. To address this issue, gain equalizers are typically introduced into the RF link for amplitude compensation.

[0003] However, existing gain equalizers have the following technical limitations:

[0004] Planar structures have high losses and low Q values: Traditional microstrip or coplanar waveguide equalizers have significant conductor losses in the millimeter-wave band (such as the W-band), making it difficult to achieve high Q-value resonance characteristics, resulting in insufficient steepness of the equalization curve.

[0005] Limited single-mode adjustment capability: Most SIW equalizers only utilize the fundamental mode (TE101) resonance. A single resonant peak is difficult to fit complex double-peak or broadband gain curves. If a cascaded structure is used, the device size will be significantly increased.

[0006] Low space utilization: Traditional designs are mostly implemented on single-layer substrates, failing to fully utilize the vertical dimension advantages of multi-layer circuits. Summary of the Invention

[0007] To address the problems of existing equalizers being large in size, having a single mode, and poor adjustment flexibility, this invention proposes a hybrid mode equalizer based on a three-dimensional multilayer substrate, consisting of SIW TE20 and TM11 modes. This structure utilizes the high airtightness and vertical integration advantages of multilayer ceramic technology to efficiently excite the circular waveguide TM11 mode through the substrate-integrated waveguide SIW TE20 mode, and achieves independently adjustable gain equalization characteristics at both frequency points by using degenerate mode perturbation.

[0008] A mixed-mode equalizer for SIW TE20 and TM11 based on a three-dimensional multilayer substrate includes: a multilayer dielectric substrate, an input-output transition structure, a substrate integrated waveguide, a circular resonant cavity, and a dual-mode perturbation device.

[0009] The multilayer dielectric substrate includes at least a first dielectric layer (upper layer) and a second dielectric layer (lower layer), and the multilayer dielectric substrate is metallized, with the surface, bottom surface and the spaces between different layers being metal surfaces.

[0010] The input-output transition structure is located at both ends of the equalizer, including a microstrip line located in the first dielectric layer and a slotted structure located between the first dielectric layer and the second dielectric layer. The microstrip line and the slotted structure enable the mutual conversion between the microstrip line mode and the second layer SIW TE20 mode.

[0011] The substrate integrated waveguide is located in the second dielectric layer and is surrounded by a metal layer and metal-filled via arrays on both sides, and is used to transmit the SIW TE20 mode;

[0012] The circular resonant cavity is located in the middle of the first dielectric layer and is surrounded by a metal via array. The circular resonant cavity is excited to the TM11 mode by the SIW TE20 mode of the lower layer through the coupling structure of the intermediate layer. The intermediate layer is a metal layer between the first dielectric layer and the second dielectric layer.

[0013] The dual-mode perturbation device includes two metal through holes symmetrical about the center located inside the circular resonant cavity. The metal through holes are used to disrupt the symmetry of the TM11 degenerate mode and generate two separate resonant absorption peaks by differentially perturbing the electric fields in different polarization directions.

[0014] Furthermore, the TM11 mode includes two orthogonal polarization modes. The two metal vias are located in the electric field zero point or weak field region of one polarization mode, so that its resonant frequency remains basically unchanged. At the same time, the two metal vias are also located in the strong electric field region of the other polarization mode, which forces the electric field distribution to be distorted, causing its resonant frequency to shift, thereby forming a double-peak characteristic in the spectrum.

[0015] Furthermore, the circular resonant cavity structure is composed of multiple cascaded circular metal through-hole array units to increase the equalizer's adjustment freedom and bandwidth.

[0016] Furthermore, the SIW TE20 mode has an electric field distribution characteristic of being out of phase on the left and right sides and zero at the center on the cross section. This characteristic matches the antisymmetric field distribution of the TM11 mode in the upper circular resonant cavity, thereby achieving efficient mode coupling.

[0017] Furthermore, the dielectric material of the multilayer dielectric substrate is aluminum oxide, the height of the dielectric substrate is 0.127 mm, the metal material is gold, and the metal layer thickness is 4 μm.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] This invention proposes an innovative structure that combines the transmission characteristics of the lower SIW TE20 mode with the degenerate mode characteristics of the upper circular waveguide TM11 mode using a three-dimensional multilayer substrate process (such as high-temperature co-fired ceramic, HTCC). By utilizing the stacked structure, the transmission layer and the resonant layer are vertically integrated, reducing the planar area of ​​the device. Combined with the fully enclosed characteristics of SIW, it has the advantages of low loss and high Q value at high frequencies (such as the W band). At the same time, this invention utilizes the degeneracy characteristics of the TM11 mode and symmetrical via perturbation in a circular resonant cavity to realize two electrically independent resonant peaks in a single physical cavity, with adjustable frequency spacing. This allows for flexible fitting of complex gain curves. Furthermore, the antisymmetry of the TE20 mode is used to excite the TM11 mode, naturally suppressing unwanted fundamental modes and improving the response accuracy of the equalizer. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of a SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate provided in an embodiment of the present invention.

[0022] Figure 2 This is a top view of a SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate provided in an embodiment of the present invention;

[0023] Figure 3 This is a front view of a SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate provided in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the input / output section provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the circular resonant cavity portion provided in an embodiment of the present invention;

[0026] Figure 6 This is a simulation result diagram of the forward transmission coefficient S21 when a preferred equalizer example provided in this embodiment of the invention is applied to the W band.

[0027] Explanation of reference numerals in the attached figures: 1-Multilayer dielectric substrate, 2-Microstrip line, 3-Substrate integrated waveguide, 4-Circular resonant cavity, 11-Input / output transition structure coupling slot, 12-Metal-filled via array, 13-Circular resonant cavity coupling slot, 14-Metal layer, 111-Left half of input / output transition structure coupling slot, 112-Right half of input / output transition structure coupling slot, 21-First microstrip line, 22-Second microstrip line, 23-Third microstrip line, 41-First metal via, 42-Second metal via, 43-Third metal via, 44-Fourth metal via, 45-Left half of circular resonant cavity coupling slot, 46-Right half of circular resonant cavity coupling slot, 47-Fifth metal via, 48-Sixth metal via. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] A mixed-mode equalizer for SIW TE20 and TM11 based on a three-dimensional multilayer substrate, the overall structure of which is as follows: Figure 1 As shown, the equalizer includes a multilayer dielectric substrate 1, an input-output transition structure, a substrate integrated waveguide 3, a circular resonant cavity 4, and a dual-mode perturbation device.

[0030] Figure 2 This is a top view of the equalizer. Figure 3This is a front view of the equalizer. The multilayer dielectric substrate 1 includes at least a first dielectric layer (upper layer) and a second dielectric layer (lower layer), and the multilayer dielectric substrate 1 is metallized, with metal surfaces on the surface, bottom surface, and between different layers. The input / output transition structure is located at both ends of the equalizer, including a microstrip line 2 located in the first dielectric layer and a slotted structure located between the first and second dielectric layers, i.e., an input / output transition structure coupling gap 11. The microstrip line 2 and the slotted structure enable the mutual conversion between the microstrip line mode and the second layer SIW TE20 mode. The substrate integrated waveguide 3 is located in the second dielectric layer and is surrounded by a metal layer and metal-filled via arrays 12 on both sides, used to transmit the SIW TE20 mode. The circular resonant cavity 4 is located in the middle of the first dielectric layer and is surrounded by a circular boundary formed by a metal via array. The circular resonant cavity 4 is coupled to the lower layer SIW via the coupling structure of the middle layer. The TE20 mode excites the TM11 mode. The intermediate layer is a metal layer 14 between the first dielectric layer and the second dielectric layer. The circular resonant cavity 4 also includes a circular resonant cavity coupling gap 13, which is a slotted structure in the circular resonant cavity. The dual-mode perturbation device includes two metal through holes symmetrical about the center located inside the circular resonant cavity. The metal through holes are used to destroy the symmetry of the TM11 degenerate mode. By perturbing the electric field in different polarization directions, two separate resonant absorption peaks are generated.

[0031] The physical structure of the equalizer consists of two dielectric substrates (defined as the upper dielectric, i.e., the first dielectric layer and the lower dielectric, i.e., the second dielectric layer) and three metal layers (the top layer, i.e., the surface, the middle layer, and the bottom layer, i.e., the bottom surface). The upper dielectric layer consists of microstrip line 2, circular resonant cavity 4, and microstrip line 2 from left to right. The lower dielectric layer consists of slotted section, substrate integrated waveguide 3, and slotted section from left to right.

[0032] The microstrip line 2 is located at both ends of the equalizer and serves as the energy inflow part of the structure. Energy flows in from the microstrip line 2 and is coupled to the substrate integrated waveguide 3 on the lower layer through the coupling gap of the intermediate metal layer, converting it into the SIW TE20 mode. The resonant frequency can be changed to the desired frequency band by optimizing and adjusting the size of the coupling gap to improve the transition effect.

[0033] In the lower dielectric layer, the intermediate metal layer, the bottom metal layer, and the metal-filled via array 12 distributed on the edge of the substrate together constitute the substrate integrated waveguide 3, which is designed to operate in TE20 mode. TE20 mode has antisymmetric characteristics with the lateral electric field being out of phase and the central electric field being zero.

[0034] Through the coupling gap, electromagnetic waves enter the circular resonant cavity 4 from the substrate integrated waveguide 3. Utilizing the antisymmetric magnetic field distribution of the lower TE20 mode, antisymmetric excitation is provided to the upper circular cavity through the coupling gap of the middle layer, thereby exciting the TM11 mode in the circular cavity.

[0035] Inside the circular resonant cavity 4, two metal through holes symmetrical about the center are provided. Since the TM11 mode has two orthogonal polarization modes, horizontal and vertical, for the first polarization mode, the two metal through holes are located at the zero electric field point of this polarization mode and do not affect its resonant frequency. For the second polarization mode, the metal through holes are in the strong electric field region, which forces the tangential electric field to be 0. The electric field is squeezed, causing the resonant frequency of this mode to shift. By changing the position or size of the through holes, the frequency of the second mode can be changed while keeping the frequency of the first mode unchanged, thereby forming two controllable absorption peaks on the S-parameter transmission curve and realizing the dual-peak equalization characteristic.

[0036] The dielectric material of the multilayer dielectric substrate 1 is aluminum oxide, the substrate height is 0.127 mm, the metal material is gold, and the metal layer 14 has a thickness of 4 μm. In this embodiment, all metal holes have the same size and are frustums of diameter with an upper radius of 26 μm and a lower radius of 39 μm. Electromagnetic waves are input along the microstrip line 2 at the edge of the dielectric substrate. In this example, to obtain a better matching effect, the microstrip line 2 is divided into three parts: the first microstrip line 21, the second microstrip line 22, and the third microstrip line 23.

[0037] like Figure 4 As shown, along the electromagnetic wave input direction, the dimensions of the first microstrip line 21, the second microstrip line 22, and the third microstrip line 23 are 0.1mm×0.02mm, 0.06mm×0.39mm, and 0.08mm×0.59mm, respectively. The electromagnetic wave flows into the substrate integrated waveguide 3 through the input-output transition structure coupling slot 11. The input-output transition structure coupling slot 11 is divided into two parts according to the axis of symmetry of the microstrip line 2. The left half 111 of the input-output transition structure coupling slot has a width of 0.07mm and a length of 0.31mm, while the right half 112 of the input-output transition structure coupling slot has a width of 0.09mm and a length of 0.67mm. The substrate integrated waveguide 3 uses a metal-filled via array 12 as its sidewalls. The hole spacing between the two vias is 0.15mm, the total length is 7.8mm, and the width is 1.4mm.

[0038] like Figure 5 As shown, the circular resonant cavity 4 is a circular array of metal vias consisting of 24 metal vias. The central angle formed by adjacent metal vias is 15°. The diameters of the first metal via 41 and the third metal via 43 are perpendicular to the electromagnetic wave propagation direction in the substrate integrated waveguide 3. The diameter formed by the second metal via 42 and the fourth metal via 44 contains two metal vias, a fifth metal via 47 and a sixth metal via 48, used to control the resonant mode. In this embodiment, the equalizer includes three circular resonant cavities 4, according to... Figure 1From left to right, in the first metal aperture array (i.e., the leftmost circular resonant cavity 4), the aperture spacing of the second metal through-hole 42 and the fifth metal through-hole 47 is 0.06 mm, and the aperture spacing of the fourth metal through-hole 44 and the sixth metal through-hole 48 is 0.04 mm. In the second metal aperture array (i.e., the middle circular resonant cavity 4), the aperture spacing of the second metal through-hole 42 and the fifth metal through-hole 47 is 0.06 mm, and the aperture spacing of the fourth metal through-hole 44 and the sixth metal through-hole 48 is 0.05 mm. In the third metal aperture array (i.e., the rightmost circular resonant cavity 4), the aperture spacing of the second metal through-hole 42 and the fifth metal through-hole 47 is 0.08 mm, and the aperture spacing of the fourth metal through-hole 44 and the sixth metal through-hole 48 is 0.06 mm.

[0039] The circular resonant cavity 4 contains two coupling slots located on the diameter of the circular metal aperture array, namely the left half 45 and the right half 46 of the circular resonant cavity coupling slot. The distance between the edge of the coupling slot closest to the center and the center is 0.18 mm. The width of the left half 45 and the right half 46 of the circular resonant cavity coupling slot are both 0.1 mm and the length is both 0.28 mm. The angle between the two slots is 120°.

[0040] Applying the equalizer from the above embodiment to the W band yields the following result: Figure 6 The simulation results of the forward transmission coefficient S21 shown indicate that the insertion loss varies between -3.5dB and -6.8dB, with the maximum attenuation groove forming at 93GHz-95GHz and an equalization depth of approximately 3dB. This demonstrates that the present invention can be applied to the field of W-band microwave and millimeter-wave devices.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mixed-mode equalizer for SIW TE20 and TM11 based on a three-dimensional multilayer substrate, characterized in that, The equalizer includes: a multilayer dielectric substrate, an input-output transition structure, a substrate integrated waveguide, a circular resonant cavity, and a dual-mode perturbation device; The multilayer dielectric substrate includes a first dielectric layer and a second dielectric layer, and the multilayer dielectric substrate is metallized, with the surface, bottom surface and the spaces between different layers being metal surfaces. The input-output transition structure is located at both ends of the equalizer, including a microstrip line located in the first dielectric layer and a slotted structure located between the first dielectric layer and the second dielectric layer. The microstrip line and the slotted structure enable the mutual conversion between the microstrip line mode and the second layer SIWTE20 mode. The substrate integrated waveguide is located in the second dielectric layer and is surrounded by a metal layer and metal-filled via arrays on both sides, and is used to transmit the SIW TE20 mode; The circular resonant cavity is located in the middle of the first dielectric layer and is surrounded by a metal via array. The circular resonant cavity is excited to the TM11 mode by the SIW TE20 mode of the lower layer through the coupling structure of the intermediate layer. The intermediate layer is a metal layer between the first dielectric layer and the second dielectric layer. The dual-mode perturbation device includes two metal through holes symmetrical about the center located inside the circular resonant cavity. The metal through holes are used to disrupt the symmetry of the TM11 degenerate mode and generate two separate resonant absorption peaks by differentially perturbing the electric fields in different polarization directions.

2. The SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate according to claim 1, characterized in that, The TM11 mode includes two orthogonal polarization modes. The two metal vias are located in the electric field zero point or weak field region of one polarization mode, while the two metal vias are also located in the strong electric field region of the other polarization mode, which forces the electric field distribution to be distorted, causing its resonant frequency to shift.

3. The SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate according to claim 1, characterized in that, The circular resonant cavity is composed of multiple cascaded circular metal through-hole array units to increase the equalizer's adjustment freedom and bandwidth.

4. The SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate according to claim 1, characterized in that, The SIW TE20 mode has an electric field distribution with out-of-phase left and right sides and zero at the center in the cross-section. This characteristic matches the antisymmetric field distribution of the TM11 mode in the upper circular resonant cavity.

5. The SIW TE20 and TM11 hybrid mode equalizer based on a three-dimensional multilayer substrate according to claim 1, characterized in that, The dielectric material of the multilayer dielectric substrate is aluminum oxide, the height of the dielectric substrate is 0.127 mm, the metal material is gold, and the metal layer thickness is 4 μm.

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