Folding substrate integrated waveguide filtering crossing device

Abstract

The invention discloses a folded substrate integrated waveguide filtering crossing device which comprises a top metal layer, a middle metal layer, a bottom metal layer, a dielectric layer, a first metalized through hole array, a second metalized through hole array, a third metalized through hole array and input and output ports. According to the filter crossing device, three cavity cascade paths of FSIW, stacked SIW and FSIW are constructed, coupling between TE0.5, 0 and 1 modes in an FSIW rectangular cavity and a TE101 mode in a middle SIW rectangular cavity is used as a design core, a filtering function is achieved on the basis of completing cross transmission between two channels, and the filter crossing device is simple in design while the compactness and high isolation performance of the structure are kept.

Description

Technical Field

[0001] This invention belongs to the field of microwave technology and relates to a filter crossover, and more particularly to a folded substrate integrated waveguide filter crossover. Background Technology

[0002] Microwave bandpass filters and crossovers play a crucial role in modern wireless communication systems. Traditional crossover architectures typically only implement signal path crossing functionality. To add filtering capabilities, the crossover must be cascaded with the bandpass filter, which usually leads to increased system size, higher insertion loss, and greater design complexity. To address these issues, there is an urgent need to integrate the bandpass filter and crossover into a single filtered crossover.

[0003] In recent years, filter crossovers based on substrate integrated waveguide (SIW) technology have been widely used in antenna feed networks and dual-frequency resonators due to their advantages such as low loss and good electromagnetic shielding. However, their size is too large, especially in low-frequency applications. To reduce size, filter crossovers based on half-mode SIW and quarter-mode SIW have been reported. These achieve this by exciting orthogonal degenerate modes (TE modes) in the full-mode SIW resonant cavity. 102 and TE 201 The half-mode and quarter-mode SIWs are coupled with two half-mode or quarter-mode cavities to achieve filtering and crossover characteristics. However, the openings of half-mode and quarter-mode SIWs have radiation losses, which compromise the overall shielding characteristics of the structure, making the circuit susceptible to external interference. Unlike half-mode SIWs, folded SIWs (FSIWs) can maintain good electromagnetic shielding while reducing the size of the SIW by half, exhibiting superior modal integrity and structural stability compared to half-mode SIWs. However, due to the relatively complex structure of FSIWs, apart from cascading two FSIW couplers to construct a broadband filtering crossover, there are no reports of FSIW-based filtering crossovers. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an FSIW filter crossover. This invention constructs a cascaded path of three cavities: FSIW-stacked SIW-FSIW, utilizing the TE in FSIW... 0.5,0,1 TE in regular SIW 101 The coupling between modes is the core of the design. Based on the cross-transmission between two channels, filtering is implemented. The intermediate SIW cavity in this invention is not only a transition coupling cavity for the cross-channel, but also acts as a mode converter, realizing TE... 0.5,0,1 Model to TE 101While achieving efficient mode switching, the passband center frequency and bandwidth can be altered through precise adjustment of the cavity size. Within the FSIW cavity, the TE frequency can be changed by adjusting the position and size of the slit. 0.5,0,1 The resonant frequency of the mode is determined, which in turn alters the passband center frequency. The design remains simple while maintaining a compact structure and high isolation performance.

[0005] The present invention adopts the following technical solution:

[0006] This invention discloses a folded substrate integrated waveguide filter crossover, comprising:

[0007] Dielectric layer;

[0008] The top metal layer is located on the upper surface of the dielectric layer;

[0009] The bottom metal layer is located on the lower surface of the dielectric layer;

[0010] The intermediate metal layer is located within the dielectric layer;

[0011] A first metallized via array connecting the top metal layer, the middle metal layer, and the bottom metal layer;

[0012] A second metallized via array connecting the intermediate metal layer and the bottom metal layer;

[0013] A third metallized via array connecting the intermediate metal layer and the top metal layer;

[0014] The top metal layer, the middle metal layer, the bottom metal layer, the dielectric layer, and the first metallized via array, the second metallized via array, and the third metallized via array together construct four FSIW rectangular cavities and one SIW rectangular cavity.

[0015] Two FSIW rectangular cavities are provided on each of the symmetrical sides of the SIW rectangular cavity;

[0016] Two FSIW rectangular cavities located on the same side share a common sidewall with the SIW rectangular cavity; one of the FSIW rectangular cavities has a first coupling window on the side of the top metal layer, and the other FSIW rectangular cavity has a second coupling window on the side of the bottom metal layer; the first coupling window is provided with only a second metallized via array, and the second coupling window is provided with only a third metallized via array.

[0017] Preferably, the center of the SIW rectangular cavity is located on the line connecting the centers of the two first coupling windows distributed on both sides of the SIW rectangular cavity.

[0018] Preferably, each of the four FSIW rectangular cavities has a third window facing outward; the intermediate metal layer also includes four striplines, which are located within the four third windows and serve as the input and output ports of the filter crossover.

[0019] Preferably, a groove is formed on each side of the strip; the groove falls within the third window.

[0020] Preferably, the two FSIW rectangular cavities located on the same side share a common sidewall, and each side of the common sidewall has a strip-shaped slit.

[0021] Preferably, the external quality factor of the input and output ports is controlled by adjusting the position TIN of the four strip lines, the length LS of the slot lines, and the width WS.

[0022] Preferably, the distance between the intermediate metal layer and the top and bottom metal layers is equal.

[0023] Preferably, the center lines of the four strip lines are equidistant from the width of the dielectric layer of the strip slit within the rectangular cavity of the FSIW, and the four strip slits have the same size and shape.

[0024] Preferably, the distance in the direction of the dielectric layer from the first coupling window to the strip slit inside the FSIW rectangular cavity is equal to the distance in the direction of the dielectric layer from the second coupling window to the strip slit inside the FSIW rectangular cavity, and the lengths of the first coupling window and the second coupling window are equal; the four FSIW rectangular cavities have the same size and shape.

[0025] Preferably, the four FSIW rectangular cavities and the centrally stacked SIW rectangular cavities form two intersecting filter channels, wherein all four FSIW rectangular cavities operate at TE. 0.5,0,1 The first mode, where the intermediate stacked SIW rectangular cavities operate in TE mode. 101 The mode, i.e., the second mode;

[0026] The implementation process of the first filtering channel is as follows: When the excitation input is given to the input / output port of one of the FSIW rectangular cavities with a first coupling window, the FSIW rectangular cavity operates in the first mode, and its energy is concentrated in the strip-shaped slit of the current FSIW rectangular cavity; the first mode couples with the SIW rectangular cavity through the first coupling window of the common sidewall, exciting TE. 101 Pattern; then, the TE generated 101 The mode couples with another FSIW rectangular cavity through a first coupling window located on the other side of the FSIW rectangular cavity, exciting TE. 0.5,0,1 In this mode, the final energy is output through the input / output ports of another FSIW rectangular cavity;

[0027] The implementation process of the second filtering channel is as follows: When the excitation input is given to the input / output port of one of the FSIW rectangular cavities with a second coupling window, the FSIW rectangular cavity operates in the first mode, and its energy is concentrated in the strip-shaped slit of the current FSIW rectangular cavity; the first mode couples with the SIW rectangular cavity through the second coupling window of the common sidewall, exciting TE. 101 Pattern; then, the TE generated 101 The mode couples with another FSIW rectangular cavity through a second coupling window located on the other side of the FSIW rectangular cavity, exciting TE. 0.5,0,1 In this mode, the final energy is output through the input / output ports of another FSIW rectangular cavity.

[0028] The present invention has the following advantages:

[0029] (1) The present invention introduces a combination of FSIW rectangular cavity and SIW rectangular cavity stacked in the middle, which greatly reduces the area and makes the layout more compact compared with the traditional filter and cross-connect cascade structure;

[0030] (2) In this invention, since the coupling paths of the two channels are independent and the electromagnetic shielding of the FSIW rectangular cavity is good, the mutual interference is minimized and the isolation between channels is good.

[0031] (3) The present invention effectively suppresses high-order mode excitation through optimized design of cavity size, power supply structure and coupling window, and exhibits good out-of-band suppression performance. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the stacked substrate integrated waveguide filter crossover structure provided in an embodiment of the present invention;

[0033] Figure 2 This is a top view of the stacked substrate integrated waveguide filter crossover provided in an embodiment of the present invention;

[0034] Figure 3 (a) Figure 3 (b) shows the TE in the rectangular cavity of the FSIW. 0.5,0,1 Mode, TE in SIW cavity 101 Electric field amplitude distribution and electric field direction diagram of the model;

[0035] Figure 4 (a) Figure 4 (b) shows the electric field distribution when port 1 and port 4 are used as input / output terminals, and the electric field distribution when port 3 and port 2 are used as input / output terminals, respectively.

[0036] Figure 5 This is the response curve of the filter crossover of the present invention from 8GHz to 12GHz.

[0037] The markings in the diagram are: 1. Dielectric layer; 2. Top metal layer; 3. Middle metal layer; 4. Bottom metal layer; 5. First metallized via array; 6. Second metallized via array; 7. Third metallized via array; 8. FSIW rectangular cavity; 9. SIW rectangular cavity; 10. First coupling window; 11. Second coupling window; 12. Third window; 13. Stripline; 14. Groove line; 15. Strip-shaped slot. Detailed Implementation

[0038] The invention will now be further described with reference to the accompanying drawings.

[0039] See appendix Figure 1-2 This embodiment provides a folded substrate integrated waveguide filter crossover with a passband set around 10 GHz. It utilizes three cascaded cavity paths—FSIW, stacked SIW, and FSIW—to construct the TE in the FSIW rectangular cavity. 0.5,0,1 Mode and TE in the intermediate SIW rectangular cavity 101 Inter-mode coupling is the core of the design. Filtering is implemented while completing cross-transmission between two channels, maintaining structural compactness and high isolation performance while simplifying the design. Specifically, it includes: dielectric layer 1, top metal layer 2, intermediate metal layer 3, bottom metal layer 4, first metallized via array 5, second metallized via array 6, and third metallized via array 7.

[0040] The top metal layer 2 is located on the upper surface of the dielectric layer 1, the bottom metal layer 4 is located on the lower surface of the dielectric layer 1, and the middle metal layer 3 is located within the middle layer of the dielectric layer 1. For example, the dielectric layer 1 can be formed by stacking two dielectric substrates, with the middle metal layer 3 located between the two dielectric substrates. The dielectric substrate is a Tanconic TLY-5 dielectric substrate with a relative permittivity of 2.2, a loss tangent of 0.0009, and a thickness of 0.508 mm.

[0041] The first metallized via array 5 is composed of a plurality of periodically distributed first metallized vias, which penetrate two dielectric substrates and connect the top metal layer 2, the middle metal layer 3, and the bottom metal layer 4.

[0042] The second metallized via array 6 is composed of a plurality of periodically distributed second metallized vias, which connect the intermediate metal layer 3 and the bottom metal layer 4.

[0043] The third metallized via array 7 is composed of multiple periodically distributed third metallized vias, which connect the intermediate metal layer 3 and the top metal layer 2.

[0044] The top metal layer 2, the middle metal layer 3, the bottom metal layer 4, the dielectric layer 1, and the first metallized via array 5, the second metallized via array 6, and the third metallized via array 7 together construct four FSIW rectangular cavities 8 and one SIW rectangular cavity 9. The top metal layer 2 and the bottom metal layer 4 cover the four FSIW rectangular cavities 8 and the SIW rectangular cavity 9.

[0045] Two FSIW rectangular cavities 8 are provided on each of the symmetrical sides of the SIW rectangular cavity 9. The two FSIW rectangular cavities 8 located on the upper left and lower left of the left side of the SIW rectangular cavity 9 are respectively designated as the first FSIW rectangular cavity and the second FSIW rectangular cavity; the two FSIW rectangular cavities 8 located on the upper right and lower right of the right side of the SIW rectangular cavity 9 are respectively designated as the third FSIW rectangular cavity and the fourth FSIW rectangular cavity.

[0046] The first FSIW rectangular cavity is located above the second FSIW rectangular cavity, and the two share a common sidewall; that is, the lower sidewall of the first FSIW rectangular cavity and the upper sidewall of the second FSIW rectangular cavity are the same sidewall. The first FSIW rectangular cavity, the second FSIW rectangular cavity, and the SIW rectangular cavity 9 share a common sidewall; that is, the right sidewall of the first FSIW rectangular cavity and the right sidewall of the second FSIW rectangular cavity are on the same straight line.

[0047] The third FSIW rectangular cavity is located above the fourth FSIW rectangular cavity, and the two share a common sidewall; that is, the lower sidewall of the third FSIW rectangular cavity and the upper sidewall of the fourth FSIW rectangular cavity are the same sidewall. The third FSIW rectangular cavity, the fourth FSIW rectangular cavity, and the SIW rectangular cavity 9 share a common sidewall; that is, the left sidewall of the third FSIW rectangular cavity and the left sidewall of the fourth FSIW rectangular cavity are on the same straight line.

[0048] The right side wall of the first FSIW rectangular cavity and the left side wall of the fourth FSIW rectangular cavity each have a first coupling window 10, and the right side wall of the second FSIW rectangular cavity and the left side wall of the third FSIW rectangular cavity each have a second coupling window 11. The first coupling window 10 is provided with only a second metallized via array 6, and the second coupling window 11 is provided with only a third metallized via array 7.

[0049] In one embodiment, the center of the SIW rectangular cavity 9 is located on the line connecting the centers of the two first coupling windows 10, and also on the line connecting the centers of the two second coupling windows 11.

[0050] In one embodiment, each of the four FSIW rectangular cavities 8 has a third window 12 facing outward; the intermediate metal layer 3 also includes four strip lines 13, which are located in the four third windows 12 respectively and serve as the input and output ports of the filter crossover.

[0051] In one embodiment, a groove 14 is opened on each side of the strip 13; the groove 14 falls within the third window 12.

[0052] In one embodiment, a strip-shaped slit 15 is opened on each side of the common sidewall of the first FSIW rectangular cavity and the second FSIW rectangular cavity, and a strip-shaped slit 15 is opened on each side of the common sidewall of the third FSIW rectangular cavity and the fourth FSIW rectangular cavity.

[0053] For example, the external quality factor of the input and output ports can be controlled by adjusting the position TIN of the four strip lines 13, the length LS of the slot line 14, and the width WS.

[0054] For example, the intermediate metal layer 3 is equidistant from the top metal layer 2 and the bottom metal layer 4.

[0055] For example, the center lines of the four striplines 13 are equidistant from the dielectric layer 1 of the strip slots within the FSIW rectangular cavity 8, all being TIN. The four strip slots 15 are identical in size and shape. The four striplines 13 employ a 50-ohm impedance.

[0056] For example, the width-direction distance from the first coupling window 10 to the dielectric layer 1 of the strip slot inside the FSIW rectangular cavity 8 is equal to the width-direction distance from the second coupling window 11 to the dielectric layer 1 of the strip slot inside the FSIW rectangular cavity 8, and the lengths of the first coupling window 10 and the second coupling window 11 are equal; the four FSIW rectangular cavities 8 are the same in size and shape.

[0057] Four FSIW rectangular cavities and a centrally stacked SIW rectangular cavity form two intersecting filter channels, with all four FSIW rectangular cavities operating at TE. 0.5,0,1 The first mode, where the intermediate stacked SIW rectangular cavities operate in TE mode. 101 The mode, also known as the second mode.

[0058] The implementation process of the first filtering channel is as follows: When the excitation input is given to the input / output port of one of the FSIW rectangular cavities with a first coupling window, the FSIW rectangular cavity operates in the first mode, and its energy is concentrated in the strip-shaped slit of the current FSIW rectangular cavity; the first mode couples with the SIW rectangular cavity through the first coupling window of the common sidewall, exciting TE. 101 The mode, which has a good bandpass response in the frequency domain, acts as a filter; then, the excited TE101 The mode couples with another FSIW rectangular cavity through a first coupling window located on the other side of the FSIW rectangular cavity, exciting TE. 0.5,0,1 In this mode, the final energy is output through the input / output ports of another FSIW rectangular cavity.

[0059] The implementation process of the second filtering channel is as follows: When the excitation input is given to the input / output port of one of the FSIW rectangular cavities with a second coupling window, the FSIW rectangular cavity operates in the first mode, and its energy is concentrated in the strip-shaped slit of the current FSIW rectangular cavity; the first mode couples with the SIW rectangular cavity through the second coupling window of the common sidewall, exciting TE. 101 Pattern; then, the TE generated 101 The mode couples with another FSIW rectangular cavity through a second coupling window located on the other side of the FSIW rectangular cavity, exciting TE. 0.5,0,1 In this mode, the final energy is output through the input / output ports of another FSIW rectangular cavity.

[0060] The entire transmission path forms the first channel, which runs from port one to the upper left FSIW rectangular cavity, then to the upper SIW rectangular cavity, then to the lower right FSIW rectangular cavity, and finally through the filtered transmission channel output from port four. The second channel runs from port three to the lower left FSIW rectangular cavity, then to the lower SIW rectangular cavity, then to the upper right FSIW rectangular cavity, and finally through the filtered transmission channel output from port two.

[0061] Figure 2 This is a top view of the filter crossover of the present invention. The width of each of the four striplines in the intermediate metal layer is P. W The length of the groove in the strip is L. S Width is W S The width of the SIW rectangular cavity is W, the length of the SIW rectangular cavity is L3, the width of the FSIW rectangular cavity is W / 2, the length of the FSIW rectangular cavity is L, the width of the strip-shaped gap in the middle metal layer is G, and the width W1 and position L2 of the first coupling window play the role of adjusting the coupling between the FSIW rectangular cavity and the SIW rectangular cavity.

[0062] Table 1. Dimensions of the filter crossover (unit: mm)

[0063]

[0064] Figure 3 (a) Figure 3 (b) shows the TE in the rectangular cavity of the FSIW. 0.5,0,1 Mode, TE in SIW cavity 101The electric field amplitude distribution and electric field direction diagrams for the modes are shown in the figure. As can be seen from the figure, the electric field of the first mode is mainly distributed at the two strip-shaped gaps in the middle metal layer, while the electric field of the second mode is distributed throughout the entire SIW rectangular cavity.

[0065] Figure 4 (a) Figure 4 Figure (b) shows the electric field distribution when port 1 (i.e., the stripline of the first FSIW rectangular cavity) and port 4 (i.e., the stripline of the fourth FSIW rectangular cavity) are used as input and output terminals, respectively. The electric field distribution when port 3 (i.e., the stripline of the third FSIW rectangular cavity) and port 2 (i.e., the stripline of the second FSIW rectangular cavity) are used as input and output terminals, respectively. As can be seen from the figure, when port 1 and port 4 are fed, the isolation ports 3 and 2 have basically no energy output. When port 3 and port 2 are fed, the isolation ports 1 and 4 have basically no energy output.

[0066] Figure 5 This is the frequency response curve of the filter crossover from 8GHz to 12GHz. As shown in the figure, the center frequency of the filter crossover is 10GHz, the -3dB bandwidth is 270MHz, the minimum insertion loss is 1.8dB, the isolation between port 1 and port 2 is -31.5dB, and the isolation between port 1 and port 3 is -25.9dB.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A folded substrate integrated waveguide filter crossover, comprising: Dielectric layer (1); The top metal layer (2) is located on the upper surface of the dielectric layer (1); The bottom metal layer (4) is located on the lower surface of the dielectric layer (1); An intermediate metal layer (3) is located within the dielectric layer (1); A first metallized via array (5) connecting the top metal layer (2), the middle metal layer (3), and the bottom metal layer (4); A second metallized via array (6) connecting the intermediate metal layer (3) and the bottom metal layer (4); A third metallized via array (7) connecting the intermediate metal layer (3) and the top metal layer (2); The feature is that the top metal layer (2), the middle metal layer (3), the bottom metal layer (4), the dielectric layer (1), and the first metallized via array (5), the second metallized via array (6), and the third metallized via array (7) together construct four FSIW rectangular cavities (8) and one SIW rectangular cavity (9); Two FSIW rectangular cavities (8) are provided on each of the symmetrical sides of the SIW rectangular cavity (9); Two FSIW rectangular cavities (8) located on the same side share a common sidewall with the SIW rectangular cavity (9); the common sidewall of one FSIW rectangular cavity (8) has a first coupling window (10) on the side of the top metal layer (2), and the common sidewall of the other FSIW rectangular cavity (8) has a second coupling window (11) on the side of the bottom metal layer (4); the first coupling window (10) is provided with only a second metallized via array (6), and the second coupling window (11) is provided with only a third metallized via array (7).

2. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, The center of the SIW rectangular cavity (9) is located on the line connecting the centers of the two first coupling windows (10) distributed on both sides of the SIW rectangular cavity (9).

3. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, Each of the four FSIW rectangular cavities (8) has a third window (12) facing outward; the intermediate metal layer (3) also includes four strip lines (13), which are located in the four third windows (12) and serve as the input and output ports of the filter crossover.

4. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, Each side of the strip (13) has a groove (14); the groove (14) falls within the third window (12).

5. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, Two FSIW rectangular cavities (8) located on the same side share a common sidewall, and each side of the common sidewall has a strip-shaped slit (15).

6. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, The external quality factor of the input and output ports can be controlled by adjusting the position TIN of the four strip lines (13), the length LS of the slot line (14), and the width WS.

7. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, The distance between the intermediate metal layer (3) and the top metal layer (2) and the bottom metal layer (4) is equal.

8. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, The center lines of the four strip lines (13) are equally spaced from the media layer (1) of the strip slits in the rectangular cavity (8) of the FSIW, and the four strip slits (15) are the same in size and shape.

9. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, The width-direction distance from the first coupling window (10) to the dielectric layer (1) of the strip-shaped gap inside the FSIW rectangular cavity (8) is equal to the width-direction distance from the second coupling window (11) to the dielectric layer (1) of the strip-shaped gap inside the FSIW rectangular cavity (8). The lengths of the first coupling window (10) and the second coupling window (11) are equal. The four FSIW rectangular cavities (8) have the same size and shape.

10. The folded substrate integrated waveguide filter crossover according to claim 1, characterized in that, The four FSIW rectangular cavities (8) and the centrally stacked SIW rectangular cavities (9) form two intersecting filtering channels, in which the four FSIW rectangular cavities (8) all operate at TE. 0.5,0,1 The first mode, where the intermediate stacked SIW rectangular cavities (9) operate in TE mode. 101 The mode, i.e., the second mode; The implementation process of the first filtering channel is as follows: When the excitation input is given to the input / output port of one of the FSIW rectangular cavities (8) with the first coupling window (10) open, the FSIW rectangular cavity (8) operates in the first mode, and its energy is concentrated in the strip slit (15) of the current FSIW rectangular cavity (8); the first mode couples with the SIW rectangular cavity (9) through the first coupling window (10) of the common sidewall, and excites TE. 101 Pattern; then, the TE generated 101 The mode is coupled to another FSIW rectangular cavity (8) through a first coupling window (10) located on the other side of the FSIW rectangular cavity (8), exciting TE. 0.5,0,1 In this mode, the energy is finally output through the input / output ports of another FSIW rectangular cavity (8); The implementation process of the second filtering channel is as follows: When the excitation input is given to the input / output port of one of the FSIW rectangular cavities (8) with a second coupling window (11), the FSIW rectangular cavity (8) operates in the first mode, and its energy is concentrated in the strip slit (15) of the current FSIW rectangular cavity (8); the first mode couples with the SIW rectangular cavity (9) through the second coupling window (11) of the common sidewall, and excites TE. 101 Pattern; then, the TE generated 101 The mode is coupled to another FSIW rectangular cavity (8) through a second coupling window (11) located on the other side of the FSIW rectangular cavity (8), exciting TE. 0.5,0,1 In the final mode, the energy is output through the input / output ports of another FSIW rectangular cavity (8).

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