A dual-passband substrate integrated waveguide filter based on orthogonal coupling slots

Abstract

The invention discloses a dual-passband substrate integrated waveguide filter based on orthogonal coupling slots. 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 group can independently couple a main mode and a first-order high-order mode to achieve the purpose of independently controlling the dual-passband bandwidth. At the same time, the coupling of the second-order high-order mode can also be suppressed to achieve the effect of increasing out-of-band suppression optimization.

Description

Technical Field

[0001] The invention relates to a dual-passband substrate integrated waveguide filter based on orthogonal coupling slots, 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, many nonlinear active devices inside the RF front end, such as mixers and multipliers, generate many interference signals 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 orthogonal coupling slots, 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 an orthogonal coupling slot 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 first slot hole pair and a second slot hole. The first slot hole pair is located at the strongest point of the main mode magnetic field and the second-order high-order mode electric field, and the second slot hole is located at the strongest point of the first-order high-order mode magnetic field.

[0010] The first slot hole pair provides magnetic coupling between the main mode and the second-order high-order mode. The magnetic coupling amount of the main mode is controlled by adjusting the length of the first slot hole. The magnetic coupling amount of the second-order high-order mode is controlled by adjusting the length of the first slot hole and the distance between the first slot hole and the nearest side wall of the resonant cavity.

[0011] The second slot hole provides magnetic coupling of the first-order high-order mode, and the magnetic coupling amount of the first-order high-order mode is controlled by adjusting the length of the second slot hole.

[0012] The two first slot holes in the first slot hole pair are arranged opposite to each other and are located on both sides of the resonant cavity. The first slot holes are parallel to the opposite side walls of the resonant cavity. The center lines of the two first slot holes in the width direction and the center line of the second slot hole in the length direction are on the same straight line. The second slot hole is orthogonal to the first slot hole, and the midpoint of the second slot hole is located on the center line of the resonant cavity.

[0013] In two adjacent metal substrates, the first slot holes located on the same side of the resonant cavity are on the same vertical plane, and the second slot holes are on the same vertical plane.

[0014] An input port is arranged on the top metal substrate, and an output port is arranged on the bottom metal substrate.

[0015] The dual-passband substrate integrated waveguide filter is a centrosymmetric structure.

[0016] 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 first-order high-order mode to achieve the purpose of independently controlling the dual-passband bandwidth. At the same time, it can also suppress the coupling of the second-order high-order mode, thereby achieving the effect of increasing the out-of-band suppression optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a three-dimensional structural diagram of the present invention;

[0018] Figure 2 A top view of the present invention;

[0019] Figure 3 The coupling coefficient between the main mode and the first-order higher-order mode extracted for the first slit hole;

[0020] Figure 4 The coupling coefficients of the main mode and the first-order higher-order mode extracted for the second slit hole;

[0021] Figure 5 The coupling coefficients of the main mode, the first-order higher-order mode and the second-order higher-order mode;

[0022] Figure 6 This is the S parameter diagram of the filter. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] The dielectric substrate is penetrated by a metallized through hole array 12, and the metallized through hole array 12 penetrated by the dielectric substrate, the upper metal substrate and the lower metal substrate together constitute a resonant cavity. A coupling hole group connecting two adjacent resonant cavities is opened on the metal substrate between two adjacent resonant cavities, and the coupling hole group includes a first slot hole pair 14 and a second slot hole 13. The first slot hole pair 14 is located at the strongest point of the main mode magnetic field and the second-order high-order mode electric field, and the second slot hole 13 is located at the strongest point of the first-order high-order mode magnetic field.

[0026] 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.

[0027] by Figure 1 For example, the middle metal substrate includes a middle first metal substrate 5, a middle second metal substrate 6 and a middle third metal substrate 7, and the dielectric substrate includes a first dielectric substrate 8, a second dielectric substrate 9, a third dielectric substrate 10 and a fourth dielectric substrate 11. The top metal substrate 3, the metallized through hole array 12 on the first dielectric substrate 8 and the middle first metal substrate 5 constitute a top resonant cavity; the middle first metal substrate 5, the metallized through hole array 12 on the second dielectric substrate 9 and the middle second metal substrate 6 constitute a first middle resonant cavity; the middle second metal substrate 6, the metallized through hole array 12 on the third dielectric substrate 10 and the middle third metal substrate 7 constitute a second middle resonant cavity, and the middle third metal substrate 7, the metallized through hole array 12 on the fourth dielectric substrate 11 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.

[0028] The first middle metal substrate 5, the second middle metal substrate 6 and the third middle metal substrate 7 are all provided with coupling hole groups, wherein the first slot hole pair 14 provides magnetic coupling between the main mode and the second-order high-order mode, and the magnetic coupling amount of the main mode is controlled by adjusting the length of the first slot hole, and the magnetic coupling amount of the second-order high-order mode is controlled by adjusting the length of the first slot hole and the distance between the first slot hole and the nearest side wall of the resonant cavity; the second slot hole 13 provides magnetic coupling of the first-order high-order mode, and the magnetic coupling amount of the first-order high-order mode is controlled by adjusting the length of the second slot hole 13.

[0029] The specific structure of the coupling hole group is shown in Figure 2 The two first slot holes in the first slot hole pair 14 are arranged opposite to each other and are located on both sides of the resonant cavity. The first slot holes are parallel to the opposite side walls of the resonant cavity. The center lines of the two first slot holes in the width direction and the center line of the second slot hole 13 in the length direction are on the same straight line. The second slot hole 13 is orthogonal to the first slot hole. The midpoint of the second slot hole 13 is located on the center line of the resonant cavity. In the two adjacent metal substrates, the first slot holes located on the same side of the resonant cavity are on the same vertical plane, and the second slot hole 13 is on the same vertical plane. In the figure, the distance between the first slot hole and the nearest side wall of the resonant cavity is 4.4 mm, and the width of the slot hole is 0.4 mm.

[0030] The first aperture pair 14 provides TE 101 Magnetic coupling of the die and providing TE 301 The second slot hole 13 provides TE 102 By adjusting the distance between the first slit hole and the nearest resonant cavity side wall, the second-order high-order mode TE 301 The magnetic coupling of the mode can reach the weakest state without affecting the main mode TE 101 The magnetic coupling of the second-order high-order mode TE can be completed. 301 In addition, the second slit hole 13 provides the first-order high-order mode TE 102 Magnetic coupling of the modes to meet the needs of passband transmission.

[0031] In order to simplify the design difficulty, the filter adopts a central symmetric 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 third metal substrate 6, and the input port 1 is rotated 180° to obtain the output port 2. Therefore, TE 102 Mode coupling can also be suppressed.

[0032] Figure 3 and Figure 4 For the extracted TE 101 TE 102The results show that by selecting the appropriate length of the first slot hole and the length of the second slot hole 13, the corresponding coupling mode can be independently controlled without affecting the other resonance mode, and the size of the passband can be easily controlled.

[0033] Figure 5 For the extracted TE 101 TE 102 TE 301 The results show that when the distance between the first slit hole and the side wall of the resonant cavity is appropriately selected, the TE 301 mode coupling suppression, while increasing the length of the corresponding coupling gap to compensate for the main mode TE 101 The coupling coefficient.

[0034] Figure 6 The S parameter curve of the filter is shown in Figure 1. The center frequency of the filter is 9 / 10 GHz, the 3-dB relative bandwidth is 4% and 6% respectively, and the in-band return loss S11 is below -20 dB. The out-of-band S parameter curve of the filter is shown in Figure 1. 301 The resonant frequency of the mode f 3 =13.16 GHz, S21 is suppressed to less than -50 dB. It can be seen that the filter designed with the above structure can independently control the passband size without affecting each other, has excellent high-order mode out-of-band suppression performance, and greatly expands the center frequency ratio range.

[0035] The filter adopts a multi-layer substrate stacking method, and the metallized through-hole array 12 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 frequency ratio of the main mode and the first-order high-order mode excitation, and realize the adjustable dual-passband frequency ratio; the coupling hole group of the filter can independently couple the main mode and the first-order high-order mode to achieve the purpose of independently controlling the dual-passband bandwidth, and at the same time can also suppress the coupling of the second-order high-order mode, so as to achieve the effect of increasing the out-of-band suppression optimization, and the cross-coupling of non-adjacent cavities introduces a transmission zero point, so that the passband selectivity is better.

[0036] 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 orthogonal coupling slots, 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 first slot hole pair and a second slot hole. The first slot hole pair is located at the strongest point of the main mode magnetic field and the second-order high-order mode electric field, and the second slot hole is located at the strongest point of the first-order high-order mode magnetic field. The first slot hole pair provides magnetic coupling between the main mode and the second-order high-order mode. The magnetic coupling amount of the main mode is controlled by adjusting the length of the first slot hole. The magnetic coupling amount of the second-order high-order mode is controlled by adjusting the length of the first slot hole and the distance between the first slot hole and the nearest side wall of the resonant cavity. The second slot hole provides magnetic coupling of the first-order high-order mode, and the magnetic coupling amount of the first-order high-order mode is controlled by adjusting the length of the second slot hole.

2. The dual-passband substrate integrated waveguide filter based on orthogonal coupling slots according to claim 1, characterized in that: The two first slot holes in the first slot hole pair are arranged opposite to each other and are located on both sides of the resonant cavity. The first slot holes are parallel to the opposite side walls of the resonant cavity. The center lines of the two first slot holes in the width direction and the center line of the second slot hole in the length direction are on the same straight line. The second slot hole is orthogonal to the first slot hole, and the midpoint of the second slot hole is located on the center line of the resonant cavity.

3. The dual-passband substrate integrated waveguide filter based on orthogonal coupling slots according to claim 1, characterized in that: In two adjacent metal substrates, the first slot holes located on the same side of the resonant cavity are on the same vertical plane, and the second slot holes are on the same vertical plane.

4. The dual-passband substrate integrated waveguide filter based on orthogonal coupling slots 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 orthogonal coupling slots 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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