阅读说明：本技术 一种高选择性宽阻带的折叠基片集成波导双模滤波器 (High-selectivity wide-stop-band folded substrate integrated waveguide dual-mode filter ) 是由 朱舫 吴云飞 赵鑫 罗国清 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种高选择性宽阻带的折叠基片集成波导双模滤波器,主要包括折叠圆形基片集成波导腔(FCSIWC)、双向折叠矩形基片集成波导腔(DFRSIWC)、内部耦合结构、外部馈电结构和50欧姆带状线。本发明利用FCSIWC的TE-(020)模、TE-(110)模以及DFRSIWC的TE-(101)模来进行双模滤波器设计,不仅在滤波器通带两侧分别产生了一个传输零点,实现了很高的频率选择性,而且还将上阻带带宽由传统的30％以下扩展到了60％。而且,相比于同类型的基片集成波导双模滤波器,本发明的尺寸减小了74％,同时在结构上保持了完全封闭的特性,从而避免了与其他电路之间的电磁干扰。(The invention discloses a high-selectivity wide-stopband folded substrate integrated waveguide dual-mode filter which mainly comprises a Folded Circular Substrate Integrated Waveguide Cavity (FCSIWC), a bidirectional folded rectangular substrate integrated waveguide cavity (DFRSIWC), an internal coupling structure, an external feed structure and a 50-ohm strip line. TE utilizing FCSIWC in accordance with the present invention 020 Mold, TE 110 TE of modulo and DFRSIWC 101 The dual-mode filter is designed in a mode, so that not only are transmission zeros respectively generated on two sides of the pass band of the filter, and high frequency selectivity is realized, but also the bandwidth of an upper stop band is expanded to 60% from the traditional bandwidth of less than 30%. Moreover, the size of the present invention is reduced by 74% compared to the same type of substrate integrated waveguide dual-mode filter, while maintaining the fully enclosed nature in structure, thereby avoiding electromagnetic interference with other circuitry.)

1. A high-selectivity wide-stop-band folded substrate integrated waveguide dual-mode filter is characterized by comprising an upper surface metal layer, a first dielectric layer, a middle metal layer, a second dielectric layer, a lower surface metal layer, a first metalized through hole and a second metalized through hole, wherein the first metalized through hole, the second metalized through hole and the lower surface metal layer are sequentially arranged from top to bottom; the middle metal layer comprises a fan-shaped metal patch, a strip-shaped metal patch and a quasi-rectangular metal patch, wherein a slot is formed in one end of the quasi-rectangular metal patch and serves as a feed end, and a feeder line is arranged in the slot;

a fan-shaped cavity, an upper surface metal layer, a fan-shaped structure metal patch and a lower surface metal layer which are formed by surrounding a plurality of first metalized through holes which are periodically distributed form a folded circular substrate integrated waveguide cavity FCSIWC;

the DFRSIWC is a bidirectional folding rectangular substrate integrated waveguide cavity which is formed by a rectangular cavity, an upper surface metal layer, a quasi-rectangular metal patch and a lower surface metal layer which are formed by surrounding a plurality of second metalized through holes which are periodically distributed;

the two-way folding rectangular substrate integrated waveguide cavities DFRSIWC are respectively positioned at two sides of the folding circular substrate integrated waveguide cavity FCSIWC;

the DFRSIWC and the FCSIWC are connected through a coupling window, and a strip-shaped metal patch used for connecting the fan-shaped metal patch and the similar rectangular metal patch is arranged in the coupling window.

2. The high-selectivity wide-stop-band folded substrate integrated waveguide dual-mode filter as claimed in claim 1, wherein a central axis of a sector cavity surrounded by the first metallized via coincides with a central axis of the sector-structured metal patch.

3. The integrated waveguide dual-mode filter with high selectivity and wide stop band on the folded substrate as claimed in claim 1, wherein the fan-shaped metal patch in the integrated waveguide cavity fcsowc on the circular folded substrate is located in the fan-shaped cavity, and the first metallized through hole forming the arc edge of the fan-shaped cavity is connected to the arc edge of the fan-shaped metal patch, and the first metallized through hole forming the two straight edges of the fan-shaped cavity is not in contact with the two straight edges of the fan-shaped metal patch.

4. The high-selectivity wide-stop-band folded substrate integrated waveguide dual-mode filter as claimed in claim 1, wherein the rectangular-like metal patch in the bidirectional folded rectangular substrate integrated waveguide cavity dfrsivc is located in the rectangular cavity, and the second metalized through holes on one long side and one short side of the rectangular cavity are connected to the rectangular-like metal patch, and the second metalized through holes on the other long side and the other short side are spaced from the rectangular-like metal patch.

5. The high selectivity wide stop band folded substrate integrated waveguide dual-mode filter of claim 1, wherein the junction of DFRSIWC and FCSIWC share a metallized via.

6. The high-selectivity wide-stop-band folded substrate integrated waveguide dual-mode filter as claimed in claim 1, wherein the feed end of the rectangular-like metal patch in the bidirectional folded rectangular substrate integrated waveguide cavity dfrsivc is disposed outward.

7. The high selectivity wide stop band folded substrate integrated waveguide dual-mode filter according to any one of claims 1-6, wherein the DFRSIWC and FCSIWC are vertically disposed.

8. The integrated waveguide dual-mode filter with high selectivity and wide stop band as claimed in any one of claims 1-6, wherein the size of the internal coupling amount is controlled by adjusting the position of the coupling window between FCSIWC and DFRSIWC, the size of the coupling window and the width of the middle strip-shaped metal patch.

9. The integrated waveguide bimodal filter with high selectivity and wide stop band as claimed in any one of claims 1 to 6, wherein the external quality factor is controlled by adjusting the depth of the grooves in the rectangular-like metal patch and the width of the coupling window.

10. The integrated waveguide dual-mode filter with high selectivity and wide stop band as claimed in any one of claims 1-6, wherein the FCSIWC has a pair of degenerate modes, TE₀₂₀Die and TE₁₁₀A pair of degenerate modes, which can be frequency separated by adjusting the angle of the sector; thus, these two resonant modes can be used to construct the passband of a dual-mode filter, and the bandwidth of the passband can be controlled by adjusting the angle of the FCSIWC sector;

TE defining input DFRSIWC₁₀₁TE with mode of resonator 1, FCSIWC₀₂₀Mode is resonator 2, TE₁₁₀TE mode of resonator 3, DFRSIWC output end₁₀₁The mode is a resonator 4, and the coupling coefficients between the resonator 1 and the resonators 2 and 3 are respectively M₁₂And M₁₃The coupling coefficients between the resonator 4 and the resonators 2 and 3 are respectively M₂₄And M₃₄(ii) a From TE₀₂₀Die and TE₁₁₀The electric field distribution of the mode is known, TE₀₂₀The mode being even mode, TE₁₁₀The module is odd, so there is M₁₂＝M₂₄,M₁₃＝-M₃₄(ii) a When theta is<77 deg. f_TE110>f_TE020If M is present₁₂/M₁₃>1, the dual-mode filter will generate a transmission zero at the upper stop band, and M₁₂/M₁₃The larger the transmission zero is, the closer the transmission zero is to the passband; meanwhile, FCSIWC's fundamental mode (TE)₀₁₀Mode) will be introduced as a non-resonant mode (NRN), sharing the same cavity with the dual modes, introducing indirect coupling between the two DFRSIWCs, thereby creating a transmission zero on the left side of the passband; therefore, two transmission zeros are respectively arranged on two sides of the passband of the filter, so that the frequency selectivity of the filter is greatly improved; in addition, the presence of higher order modes in the FCSIWC will create additional parasitic coupling and thus additional transmission zeros in the upper stop band of the filter.

Technical Field

The invention belongs to the technical field of microwaves, relates to a high-selectivity wide-stopband Folded Substrate Integrated Waveguide (FSIW) dual-mode filter, and particularly relates to a high-selectivity wide-stopband dual-mode filter combining a Folded Circular Substrate Integrated Waveguide Cavity (FCSIWC) and a bidirectional folded rectangular substrate integrated waveguide cavity (DFRSIWC).

Background

Modern wireless communication systems require microwave filters that combine the characteristics of high selectivity, wide stop band, low loss, ease of processing, miniaturization, and the like. Substrate Integrated Waveguide (SIW) filters have gained extensive research and application in the microwave field due to their advantages of low loss, low profile, ease of processing, ease of integration with other planar circuits, and the like. However, the conventional SIW has a large size and cannot meet the requirement of the modern microwave circuit for miniaturization, so that structures such as the semi-membrane SIW (hmsiw), the quarter-module SIW (qmsiw) and the eighth-module SIW (emsiw) are proposed in succession. These semi-open structures, while smaller in size, also increase the radiation loss of the filter and interference with other circuitry. Folding SIW (FSIW) not only reduces the size of SIW, but also has a completely closed characteristic, but FSIW filters generally have difficulty achieving higher frequency selectivity.

On the other hand, the dual-mode SIW filter has become a hot research spot of the current SIW filter due to the advantages of high frequency selectivity and relatively smaller size. But the upper stop band bandwidth of a dual-mode filter is typically less than 30% due to the higher order modes present in the SIW cavity. Recently, a SIW Box-like filter using a combination of a SIW dual-mode rectangular cavity and a SIW single-mode rectangular cavity has been proposed to achieve an upper stop band bandwidth of about 60%. However, the filter can only generate transmission zero on one side of the passband, so that the frequency selectivity on one side of the passband can be improved, and two SIW single-mode rectangular cavities are required to have different width-length ratios in order to obtain a wide stopband, thereby greatly increasing the design complexity of the filter. In addition, since all cavities are full-mode SIW cavities, the size of the filter is still large.

Aiming at the problems, the invention provides a novel dual-mode band-pass filter combining FCSIWC and DFRSIWC, which not only realizes 60% of upper stop band bandwidth, but also has the advantages of high frequency selectivity, small size, full sealing, simple design and the like.

Disclosure of Invention

The invention aims to provide a novel dual-mode band-pass filter combining FCSIWC and DFRSIWC aiming at the defects of the prior art, which improves the frequency selectivity of the filter by utilizing the dual-mode characteristic of the FCSIWC, widens the upper stop band bandwidth of the filter by utilizing the higher high-order mode frequency characteristic of the DFRSIWC, and has the advantages of small size, full sealing, simple design and the like.

The invention adopts the following technical scheme:

the invention relates to an FSIW dual-mode filter with high selectivity and wide stop band, which comprises an upper surface metal layer, a first medium layer, a middle metal layer, a second medium layer, a lower surface metal layer, a first metalized through hole and a second metalized through hole, wherein the first metalized through hole, the middle metal layer, the second medium layer and the lower surface metal layer are sequentially arranged from top to bottom; the middle metal layer comprises a fan-shaped metal patch, a strip-shaped metal patch and a quasi-rectangular metal patch, wherein one end of the quasi-rectangular metal patch is provided with a slot as a feed end, a feeder line is arranged in the slot, namely one end of the feeder line is connected with the quasi-rectangular metal patch, and the other end of the feeder line is connected with a 50-ohm strip line;

a fan-shaped cavity, an upper surface metal layer, a fan-shaped structure metal patch and a lower surface metal layer which are formed by surrounding a plurality of first metalized through holes which are periodically distributed form a folded circular substrate integrated waveguide cavity FCSIWC;

the DFRSIWC is a bidirectional folding rectangular substrate integrated waveguide cavity which is formed by a rectangular cavity, an upper surface metal layer, a quasi-rectangular metal patch and a lower surface metal layer which are formed by surrounding a plurality of second metalized through holes which are periodically distributed;

the two-way folding rectangular substrate integrated waveguide cavities DFRSIWC are respectively positioned at two sides of the folding circular substrate integrated waveguide cavity FCSIWC;

a coupling window is arranged at the joint of the DFRSIWC and the FCSIWC, and a banded metal patch for connecting the fan-shaped structure metal patch and the quasi-rectangular metal patch is arranged in the coupling window;

the two coupling windows are not provided with metalized through holes.

Preferably, a certain gap is reserved between the two sides of the feeder line and the quasi-rectangular metal patch;

preferably, the fan-shaped metal patch in the FCSIWC is positioned in the fan-shaped cavity, the first metalized through holes forming the arc edge of the fan-shaped cavity are connected with the arc edge of the fan-shaped metal patch, the first metalized through holes forming the two linear edges of the fan-shaped cavity are not in contact with the two linear edges of the fan-shaped metal patch, and a certain distance S is reserved;

preferably, the central axis of the fan-shaped cavity surrounded by the first metalized through hole is superposed with the central axis of the fan-shaped structural metal patch;

preferably, the quasi-rectangular metal patch in the DFRSIWC is positioned in the rectangular cavity, the second metalized through holes on one long side and one short side of the rectangular cavity are connected with the quasi-rectangular metal patch, and a certain distance S is reserved between the second metalized through holes on the other long side and the other short side of the rectangular cavity and the quasi-rectangular metal patch;

preferably, the DFRSIWC is vertically arranged with the FCSIWC;

preferably, the junction of the DFRSIWC and the FCSIWC shares a metalized through hole, the feed end of the quasi-rectangular metal patch is arranged outwards, and the feed end is provided with a coupling window;

radius l of FCSIWC₁Determines TE in the dual-mode cavity₀₂₀The resonant frequency of the mode, the angle θ of which determines the TE in the cavity₁₁₀Die and TE₀₂₀The relative frequency magnitudes of the modes.

TE utilizing FCSIWC in accordance with the present invention₀₂₀Mold, TE₁₁₀TE of modulo and DFRSIWC₁₀₁The modes build the pass band of the filter. By adjusting the radius l of FCSIWC₁Controlling TE₀₂₀Resonant frequency (f) of the mode_TE020) To make it equal to the center frequency of the filter, and then adjust the sector angle control TE of FCSIWC₁₁₀Mode resonance frequency (f)_TE110) When the angle is 77 degrees, f_TE110＝f_TE020(ii) a The DFRSIWC is set to have a length and a width of TE₁₀₁Resonant frequency (f) of the mode_TE101) Equal to the center frequency of the filter. The size of the internal coupling amount can be controlled by adjusting the position of the coupling window between the FCSIWC and the DFRSIWC, the size of the coupling window and the width of the middle strip-shaped metal patch; by adjusting the length c of the feed line and the width d of the coupling window₂The magnitude of the external figure of merit can be controlled.

The specific working principle is as follows:

having a pair of degenerate modes in FCSIWC, i.e. TE₀₂₀Die and TE₁₁₀Mode, the pair of degenerate modes may be frequency separated by adjusting the angle θ of the sector. Thus, these two resonant modes can be used to construct the passband of a dual-mode filter, and the bandwidth of the passband can be controlled by adjusting the angle of the FCSIWC sector.

TE defining input DFRSIWC₁₀₁TE with mode of resonator 1, FCSIWC₀₂₀Mode is resonator 2, TE₁₁₀TE mode of resonator 3, DFRSIWC output end₁₀₁The mode is a resonator 4, and the coupling coefficients between the resonator 1 and the resonators 2 and 3 are respectively M₁₂And M₁₃The coupling coefficients between the resonator 4 and the resonators 2 and 3 are respectively M₂₄And M₃₄. From TE₀₂₀Die and TE₁₁₀The electric field distribution of the mode is known, TE₀₂₀The mode being even mode, TE₁₁₀The module is odd, so there is M₁₂＝M₂₄,M₁₃＝-M₃₄. When theta is<77 deg. f_TE110>f_TE020If M is present₁₂/M₁₃>1, the dual-mode filter will generate a transmission zero at the upper stop band, and M₁₂/M₁₃The larger the transmission zero, the closer the transmission zero is to the passband. Meanwhile, FCSIWC's fundamental mode (TE)₀₁₀Mode) will be introduced as a non-resonant mode (NRN), sharing the same cavity as the dual modes, introducing indirect coupling between the two DFRSIWCs, thereby creating a transmission zero on the left side of the passband. Therefore, two transmission zeros are respectively arranged on two sides of the passband of the filter, and the frequency selectivity of the filter is greatly improved. In addition, the presence of higher order modes in the FCSIWC will create additional parasitic coupling and thus additional transmission zeros in the upper stop band of the filter.

Because both the FCSIWC and the dfrsivc adopt the FSIW structure, the structure reduces the size of the cavity and the radiation loss, and simultaneously improves the upper stop band performance of the SIW filter, because some high-order modes in the FCSIWC and the dfrsivc cannot be excited by the strip line, and the resonance frequencies of the excited high-order modes are different, so that effective coupling is difficult to form between the high-order modes and the low-order modes.

The invention has the following advantages:

(1) by adopting an FSIW cavity structure (comprising FCSIWC and DFRSIWC), the size of the filter is reduced, and the area of the filter is 26% of that of a SIW Box-like filter of the same type;

(2) the upper stop band bandwidth of the traditional SIW dual-mode filter is expanded (from less than 30% to 60%);

(3) two transmission zeros are respectively arranged at the positions, close to the pass band, of the two sides of the pass band, so that the frequency selectivity of the dual-mode filter is improved;

(4) the upper stop band of the filter is provided with an additional transmission zero, so that the stop band rejection degree of the filter is improved;

(5) the structure is completely closed, so that the radiation loss and the interference with other circuits are reduced;

(6) the circuit structure is symmetrical, and the design process is simplified.

Drawings

FIG. 1 is a schematic three-dimensional structure of the present invention;

FIG. 2 is a schematic view of the structure of the intermediate metal layer of the present invention and along a₁a₂A schematic cross-sectional view of;

FIG. 3 is a view along a of the present invention₁a₂A schematic cross-sectional view of;

FIG. 4 is the TE in FCSIWC₀₁₀Mold, TE₀₂₀Die and TE₁₁₀A plot of the resonant frequency of the mode as a function of θ;

FIG. 5 is TE in FCSIWC₀₁₀Mold, TE₀₂₀Die and TE₁₁₀The electric field profile of the mode;

FIG. 6 is a filter topology;

FIG. 7 is a frequency response curve of the present invention;

the labels in the figure are: FCSIWC 1, dfrsivc 2, internal coupling structure 3, external feed structure 4, 50 ohm stripline 5, upper surface metal layer 6, first dielectric layer 7, intermediate metal layer 8, second dielectric layer 9, lower surface metal layer 10, first metalized via 11, second metalized via 12.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

As shown in fig. 1-3, the FSIW dual-mode filter with high selectivity and wide stop band provided by the present invention includes FCSIWC 1, DFRSIWC 2, internal coupling structure 3, external feeding structure 4 and 50 ohm strip line 5. As can be seen from fig. 3, the whole structure is sequentially provided with an upper surface metal layer 6, a first dielectric layer 7, a middle metal layer 8, a second dielectric layer 9 and a lower surface metal layer 10 from top to bottom; the first metallized through holes 11 arranged periodically penetrate through the whole structure to connect the upper and lower surface metal layers, so as to form the metal side wall of the FCSIWC cavity. Second metallized vias 12, which are periodically arranged, extend through the entire structure and connect the upper and lower surface metal layers to form the metal sidewalls of the dfrsivc cavity.

Both FCSIWC 1 and DFRSIWC 2 are FSIW structure, wherein FCSIWC 1 is a 69-degree fan structure with radius l₁And the two sides of the fan-shaped metal in the middle metal layer are not connected with the metal side wall of the FCSIWC 1, and the distance between the two is s. DFRSIWC 2 is rectangular structure, and one side long edge and broadside of its middle metal layer also do not link with the metal lateral wall, and the interval between the two is s. Two DFRSIWC 2 are respectively positioned at two sides of the FCSIWC 1 and are vertical to the FCSIWC 1, and the distance between the two DFRSIWC 2 and the center of the FCSIWC 1 is m₁(ii) a An internal coupling structure 3 is provided between FCSIWC 1 and DFRSIWC 2, including a width d₃And a coupling window of width w₂The strip-shaped metal patch of (1). In addition, the internal coupling structure 3 is m away from the center of the FCSIWC 1₂。

The 50 ohm stripline 5 is used for connecting the input/output port, and an external feeding structure 4 is arranged between the stripline and the DFRSIWC 2, and comprises a width d₂And two sections of slits which are distributed on two sides of the 50 ohm strip line 5 and have the length and width of c and s respectively.

The invention adopts FSIW structure, the radius of the metallized through hole is r, and the distance between two adjacent through holes is d₁. DFRSIWC 2 has length l₂Width of l₃Wherein the gap distance DFRSIWC 2 is m₃。

The final dimensions are shown in the following table (unit: mm):

r	s	s1	d1	d2	d3	w1	w2
								0.25	0.6	0.45	0.8	5.15	2.5	1.45	0.2
m1	m2	m3	c	l1	l2	l3
								2.76	4.88	2.1	5.4	18.72	10.3	6.65

FIG. 4 is the TE in FCSIWC₀₁₀Mold, TE₀₂₀Die and TE₁₁₀A plot of the resonant frequency of the mode versus θ. In this example, Rogers RT/duroid 5880(tm) of 0.88mm thickness with a relative permittivity of 2.2 was used for both the first and second dielectric layers. As can be seen, as θ increases, the TE principal mode₀₁₀Die and TE₀₂₀The resonant frequency of the mode remains substantially constant while TE₁₁₀The resonant frequency of the mode is continuously reduced along with the increase of theta and is in inverse proportion; when theta is<77 deg. g, TE₁₁₀Mode resonance frequency greater than TE₀₂₀Resonant frequency of mode, TE when θ is 77deg₁₁₀Mode resonance frequency equal to TE₀₂₀Resonant frequency of mode, and when theta>77 deg. g, TE₁₁₀Mode resonance frequency less than TE₀₂₀The resonant frequency of the mode. Therefore, f can be conveniently controlled by adjusting the angle theta of the fan shape_TE020And f_TE110And thus the bandwidth of the filter.

FIG. 5 is TE in FCSIWC chamber₀₁₀Mold, TE₀₂₀Die and TE₁₁₀The electric field profile of the mode. As can be seen, TE₀₁₀Die and TE₀₂₀The electric field distribution of the modes is even symmetric (equal amplitude and same phase) in the z-axis direction, while TE₁₁₀The electric field distribution of the modes is odd symmetric (equal amplitude, opposite phase) in the z-axis direction. Therefore, when the feeding method shown in FIG. 1 is adoptedCan yield M₁₂＝M₂₄,M₁₃＝-M₃₄。

FIG. 6 is a topological structure diagram of the present invention, wherein resonators 1 and 4 represent the main mode of DFRSIWC, and resonators 2 and 3 represent TE of FCSIWC₀₂₀Die and TE₁₁₀Modulo, TE with N being FCSIWC₀₁₀And (5) molding.

Fig. 7 is a frequency response curve of the present invention. As can be seen, the center frequency of the filter is 10GHz, the bandwidth is 0.81GHz (relative bandwidth is 81%), and the insertion loss is 0.56 dB. The invention respectively generates a transmission zero on two sides of the passband, wherein the transmission zero on the left side is generated by NRN and is positioned at 9.22GHz, the transmission zero on the right side is generated by a dual-mode structure and is positioned at 10.6GHz, and the frequency selectivity of the filter is greatly improved. In addition, the parasitic pass band of the upper stop band is positioned near 16.08GHz, namely the bandwidth of the upper stop band reaches 60%, and two additional transmission zeros are generated at 14.52GHz and 15.72GHz, so that the stop band rejection degree of the filter is improved.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.