A dual-passband substrate integrated waveguide filter based on hybrid coupling

Abstract

The invention discloses a dual-passband substrate integrated waveguide filter based on hybrid coupling. The invention adopts a multi-layer substrate stacking method. Adjacent metal substrates and metallized through-hole arrays between adjacent metal substrates form a resonant cavity. Adjacent resonant cavities are connected by coupling hole groups, so that the filter structure is more compact and the integrity of the circuit as a whole is guaranteed. The filter is more suitable for application in modern microwave millimeter wave integrated circuit systems. The coupling hole groups can independently couple the main mode and the high-order mode to achieve the purpose of independently controlling the bandwidth of the dual-passband. At the same time, the cross-electric coupling path of the main mode can be realized by a circular hole, so that the transmission zero point symmetry of the dual-passband is realized, so that the isolation between the passbands and the out-of-band suppression are better.

Description

Technical Field

[0001] The invention relates to a dual-passband substrate integrated waveguide filter based on hybrid coupling, belonging to the technical field of microwaves. Background Art

[0002] As an important component in RF microwave circuit systems, filters have been developing towards low cost, low power consumption, small size, high power handling capability, and easy integration. Substrate integrated waveguide filters combine waveguides and planar structures, and have the advantages of small size, low loss, and easy integration with planar circuits.

[0003] As the number of channels in modern communication circuit systems increases, a communication system may have dozens of channels. The traditional single-channel filtering method will cause the circuit size to increase dramatically, increase the design complexity, and increase costs in all aspects. On the other hand, affected by the parasitic harmonics generated by nonlinear active devices, many interference signals close to the passband are generated outside the passband, which seriously affects the transmission quality inside the channel.

[0004] In order to solve the above problems, the filter needs to transmit multiple channels in one path. Therefore, it is urgent to study dual-passband substrate integrated waveguide filters. Summary of the invention

[0005] The invention provides a dual-passband substrate integrated waveguide filter based on hybrid coupling, which solves the problems disclosed in the background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A dual-passband substrate integrated waveguide filter based on hybrid coupling comprises a stacked top metal substrate and a bottom metal substrate, a plurality of intermediate metal substrates are stacked between the top metal substrate and the bottom metal substrate, and a dielectric substrate is stacked between adjacent metal substrates;

[0008] A metallized through hole array is passed through the dielectric substrate, and the metallized through hole array passed through the dielectric substrate, the upper metal substrate and the lower metal substrate together constitute a resonant cavity;

[0009] A coupling hole group connecting the two adjacent resonant cavities is opened on the metal substrate between the two adjacent resonant cavities. The coupling hole group includes a slit hole pair and a combination hole. The slit hole pair is located at the strongest magnetic field of the main mode. The combination hole includes a slit hole and a circular hole. The slit hole in the combination hole is located at the strongest magnetic field of the high-order mode, and the circular hole is located at the strongest electric field of the main mode.

[0010] The slot hole pair provides magnetic coupling of the main mode in the main coupling path, and the magnetic coupling amount of the main mode is controlled by adjusting the length of the slot hole in the slot hole pair;

[0011] The slot holes in the combined hole provide magnetic coupling of the high-order mode, and the magnetic coupling amount of the high-order mode is controlled by adjusting the length of the slot holes in the combined hole;

[0012] The circular hole provides cross-electric coupling for the main mode, and the amount of cross-electric coupling of the main mode can be controlled by adjusting the radius of the circular hole.

[0013] The slot hole pair comprises two slot holes which are arranged opposite to each other and are located on both sides of the resonant cavity, and the slot holes of the slot hole pair are parallel to the opposite side walls of the resonant cavity;

[0014] The center of the circular hole is located on the center line of the resonant cavity; the slit hole of the combined hole passes through the center of the circular hole, and the center is located at the midpoint of the slit hole of the combined hole, and the slit hole of the combined hole is perpendicular to the slit holes of the slit hole pair.

[0015] In two adjacent metal substrates, the slot holes of the slot hole pair located on the same side of the resonant cavity are on the same vertical plane, and the combined hole is on the same vertical plane at the center position.

[0016] An input port is arranged on the top metal substrate, and an output port is arranged on the bottom metal substrate.

[0017] The dual-passband substrate integrated waveguide filter is a centrosymmetric structure.

[0018] The beneficial effects achieved by the present invention are as follows: the present invention adopts a multi-layer substrate stacking method, and the metallized through-hole arrays between adjacent metal substrates and adjacent metal substrates constitute a resonant cavity. The adjacent resonant cavities are connected by a coupling hole group, so that the filter structure is more compact and the integrity of the overall circuit is guaranteed. It is more suitable for application in modern microwave millimeter wave integrated circuit systems, and the coupling hole group can independently couple the main mode and the high-order mode to achieve the purpose of independently controlling the dual-passband bandwidth. At the same time, the cross-electric coupling path of the main mode can be realized through the circular hole, realizing the transmission zero point symmetry of the dual-passband, so that the isolation between the passbands and the out-of-band suppression are better. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional structural diagram of the present invention;

[0020] Figure 2 is a top view of the first metal substrate in the middle;

[0021] Figure 3 is a top view of the second metal substrate in the middle;

[0022] Figure 4 is the coupling coefficient of the main mode and higher-order modes extracted by the slit-hole pair;

[0023] Figure 5 Coupling coefficients of the main and higher-order modes extracted for the slot holes of the combined holes;

[0024] Figure 6 is the S21 parameter diagram with the circular hole radius as a variable;

[0025] Figure 7 This is the S parameter diagram of the filter. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0027] like Figure 1 As shown, a dual-passband substrate integrated waveguide filter based on hybrid coupling includes a stacked top metal substrate 3 and a bottom metal substrate 4, a plurality of intermediate metal substrates are stacked between the top metal substrate 3 and the bottom metal substrate 4, and a dielectric substrate is stacked between adjacent metal substrates.

[0028] The dielectric substrate is penetrated by a metallized through hole array 10, and the metallized through hole array 10 penetrated by the dielectric substrate, the upper metal substrate and the lower metal substrate together constitute a resonant cavity. A coupling hole group connecting the two adjacent resonant cavities is opened on the metal substrate between the two adjacent resonant cavities, and the coupling hole group includes a slot hole pair 12 and a combination hole 11, and the slot hole pair 12 is located at the strongest magnetic field of the main mode, and the combination hole 11 includes a slot hole and a circular hole, and the slot hole in the combination hole 11 is located at the strongest magnetic field of the high-order mode, and the circular hole is located at the strongest electric field of the main mode.

[0029] An input port 1 is provided on the top metal substrate 3, which is generally a microstrip line connected to the top resonant cavity; an output port 2 is provided on the bottom metal substrate 4, which is generally a microstrip line connected to the bottom resonant cavity.

[0030] by Figure 1 For example, the middle metal substrate includes a middle first metal substrate 5 and a middle second metal substrate 6, and the dielectric substrate includes a first dielectric substrate 7, a second dielectric substrate 8 and a third dielectric substrate 9. The top metal substrate 3, the metallized through hole array 10 on the first dielectric substrate 7, and the middle first metal substrate 5 constitute a top resonant cavity; the middle first metal substrate 5, the metallized through hole array 10 on the second dielectric substrate 8, and the middle second metal substrate 6 constitute a first middle resonant cavity; the middle second metal substrate 6, the metallized through hole array 10 on the third dielectric substrate 9, and the bottom metal substrate 4 constitute a bottom resonant cavity; the metallized through holes on all dielectric substrates have the same size, with a radius of 0.5 mm and a spacing of 1.4 mm.

[0031] The first middle metal substrate 5 and the second middle metal substrate 6 are both provided with coupling hole groups, wherein the slot hole pair 12 provides magnetic coupling of the main mode in the main coupling path, and the magnetic coupling amount of the main mode is controlled by adjusting the length of the slot holes in the slot hole pair 12; the slot holes in the combination hole 11 provide magnetic coupling of the higher-order modes, and the magnetic coupling amount of the higher-order modes is controlled by adjusting the length of the slot holes in the combination hole 11; the circular hole provides cross-electric coupling of the main mode, and the cross-electric coupling amount of the main mode is controlled by adjusting the radius of the circular hole.

[0032] The specific structure of the coupling hole group is shown in Figure 2 and 3 The slot hole pair 12 includes two slot holes that are arranged opposite to each other and located on both sides of the resonance cavity. The slot holes of the slot hole pair 12 are parallel to the opposite side walls of the resonance cavity. The slot holes of the slot hole pair 12 are 0.8 mm away from the side walls of the resonance cavity and have a width of 0.4 mm. The center of the circular hole is located on the center line of the resonance cavity, with a radius of 2 mm. The slot hole of the combination hole 11 passes through the center of the circular hole, and the center of the circle is located at the midpoint of the slot hole of the combination hole 11. The slot hole width of the combination hole 11 is 0.4 mm. The slot hole of the combination hole 11 is perpendicular to the slot hole of the slot hole pair 12. In the two adjacent metal substrates, i.e., the first middle metal substrate 5 and the second middle metal substrate 6, the slot holes of the slot hole pair 12 located on the same side of the resonance cavity are on the same vertical plane, and the combination hole 11 is on the same vertical plane of the center of the circle.

[0033] The slot hole pair 12 provides TE 101 The magnetic coupling of the mode, the gap hole of the combination hole 11 provides TE 102 The circular hole provides TE 101 The cross electrical coupling of the TE mode can be controlled by the radius of the circular hole. 101 Cross-electric coupling between non-adjacent resonant cavities in this mode.

[0034] In order to simplify the design difficulty, the filter adopts a central symmetrical structure, that is, the top resonant cavity is rotated 180° to obtain the bottom resonant cavity, the coupling hole group on the middle first metal substrate 5 is rotated 180° to obtain the coupling hole group on the middle second metal substrate 6, and the input port 1 is rotated 180° to obtain the output port 2. Therefore, TE 201 Mode coupling can also be suppressed.

[0035] Figure 4 and Figure 5 For the extracted TE 101 TE 102 The results show that by selecting the appropriate length of the slot hole pair 12 and the length of the slot hole of the combination hole 11, the independent control of the corresponding coupling mode can be achieved without affecting the other resonant mode, and the size of the passband can be easily controlled.

[0036] Figure 6 The figure is an S-parameter diagram of the effect of the circular hole radius in a combination hole 11 on the transmission zero point of the first passband. The results show that by selecting an appropriate circular hole radius, the passband isolation and out-of-band suppression between the upper and lower passbands can be improved.

[0037] Figure 7 The S parameter curve of the filter, the center frequency of the filter is 6 / 9 GHz, the 3-dB relative bandwidth is 5%, and the in-band return loss S11 is below -20 dB. The out-of-band S parameter curve of the filter, the zero point of the first passband and the second passband is symmetrical, and the S21 between the passbands is suppressed below -25 dB. It can be seen that the filter designed with the above structure can independently control the passband size without affecting each other, and the zero point symmetry between the two passbands makes the out-of-band suppression and isolation performance excellent.

[0038] The filter adopts a multi-layer substrate stacking method, and the metallized through-hole array 10 between adjacent metal substrates and adjacent metal substrates constitutes a resonant cavity. The adjacent resonant cavities are connected by a coupling hole group, which makes the filter structure more compact and ensures the integrity of the overall circuit, and is more suitable for application in modern microwave millimeter wave integrated circuit systems; the aspect ratio of the circuit size of the resonant cavity of the filter can effectively control the center frequency ratio of the main mode and the high-order mode resonance, and realize the adjustable dual-passband frequency ratio; the coupling hole group of the filter can independently couple the main mode and the high-order mode to achieve the purpose of independently controlling the dual-passband bandwidth. At the same time, the cross-electric coupling path of the main mode can be realized through the circular hole, realizing the transmission zero point symmetry of the dual passband, so that the isolation between the passbands and the out-of-band suppression are better.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-passband substrate integrated waveguide filter based on hybrid coupling, characterized in that: It comprises a stacked top metal substrate and a bottom metal substrate, a plurality of middle metal substrates are stacked between the top metal substrate and the bottom metal substrate, and a dielectric substrate is stacked between adjacent metal substrates; A metallized through hole array is passed through the dielectric substrate, and the metallized through hole array passed through the dielectric substrate, the upper metal substrate and the lower metal substrate together constitute a resonant cavity; A coupling hole group connecting the two adjacent resonant cavities is provided on the metal substrate between the two adjacent resonant cavities. The coupling hole group includes a slot hole pair and a combination hole. The slot hole pair is located at the strongest magnetic field of the main mode. The combination hole includes a slot hole and a circular hole. The slot hole in the combination hole is located at the strongest magnetic field of the high-order mode, and the circular hole is located at the strongest electric field of the main mode. The slot hole pair provides magnetic coupling of the main mode in the main coupling path, and the magnetic coupling amount of the main mode is controlled by adjusting the length of the slot hole in the slot hole pair; The slot holes in the combined holes provide magnetic coupling for the higher-order modes, and the magnetic coupling amount of the higher-order modes can be controlled by adjusting the length of the slot holes in the combined holes. The circular hole provides cross-electric coupling for the main mode, and the amount of cross-electric coupling of the main mode can be controlled by adjusting the radius of the circular hole.

2. The dual-passband substrate integrated waveguide filter based on hybrid coupling according to claim 1, characterized in that: The slot hole pair comprises two slot holes which are arranged opposite to each other and are located on both sides of the resonant cavity, and the slot holes of the slot hole pair are parallel to the opposite side walls of the resonant cavity; The center of the circular hole is located on the center line of the resonant cavity; the slit hole of the combined hole passes through the center of the circular hole, and the center is located at the midpoint of the slit hole of the combined hole, and the slit hole of the combined hole is perpendicular to the slit holes of the slit hole pair.

3. The dual-passband substrate integrated waveguide filter based on hybrid coupling according to claim 1, characterized in that: In two adjacent metal substrates, the slot holes of the slot hole pair located on the same side of the resonant cavity are on the same vertical plane, and the combined hole is on the same vertical plane at the center position.

4. The dual-passband substrate integrated waveguide filter based on hybrid coupling according to claim 1, characterized in that: An input port is arranged on the top metal substrate, and an output port is arranged on the bottom metal substrate.

5. The dual-passband substrate integrated waveguide filter based on hybrid coupling according to any one of claims 1 to 4, characterized in that: The dual-passband substrate integrated waveguide filter is a centrosymmetric structure.

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