阅读说明：本技术 一种高共模抑制的平衡滤波交叉结 (balanced filtering cross-node with high common-mode rejection ) 是由 孙亮 薛一凡 邢思贝 朱家明 邓宏伟 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种高共模抑制的平衡滤波交叉结,适用于较高的厘米波和毫米波频段。SIW平衡滤波交叉结的主体部分是位于中间层的五个SIW谐振腔,还有四对差分端口,分别为：第一、第二、第三和第四差分端口。本发明利用成对的微带-槽线转换结构对SIW谐振腔进行差分馈电,槽线和耦合窗口均位于SIW谐振腔的中心位置处。在差模激励下,第一差分端口和第二差分端口、第三差分端口和第四差分端口之间可分别传输具有三阶带通频率响应特性的差分信号,且相互之间具有高隔离。同时,由于SIW本身固有的差分传输特性,共模信号(噪声)被全反射,实现了良好的共模抑制性能。本发明所述SIW差分滤波交叉结具有结构紧凑、高隔离度以及高共模抑制等特点。(The invention discloses balanced filtering cross junctions with high common mode rejection, which are suitable for higher centimeter wave and millimeter wave frequency bands.A main body part of the SIW balanced filtering cross junctions is five SIW resonant cavities positioned at an intermediate layer, and also comprises four pairs of differential ports, namely a th differential port, a second differential port, a third differential port and a fourth differential port.)

The balanced filtering cross-junction with high common mode rejection of kinds is characterized by comprising a dielectric substrate , a metal surface , a dielectric substrate II, a metal surface II and a dielectric substrate III which are coaxially arranged from top to bottom in sequence;

the other four SIW resonant cavities have the same size and are arranged around the SIW cavity III, and the four side walls of the SIW cavity III realize energy coupling with the adjacent SIW resonant cavities through coupling windows respectively;

four feed microstrip lines are arranged on the dielectric substrate and the dielectric substrate III, four rectangular gaps are arranged on the metal surface and the metal surface II, and the rectangular gaps are used for realizing the coupling between the feed microstrip lines and the SIW resonant cavity.

2. A balanced filter crossover junction with high common mode rejection according to claim 1, wherein: the coupling window is positioned in the center of the side edges of the three opposite sides of the SIW cavity.

3. The balanced filter cross-over junction with high common-mode rejection of claim 1 or 2, wherein third-order balanced band-pass filters are formed by five SIW resonators, using pairs of orthogonal degenerate modes TE in the SIW resonators₁₀₂And TE₂₀₁Modulo, TE when differential signal excitation is achieved₁₀₂And TE₂₀₁Normal excitation of the mode without mutual interference; while the common mode signal is suppressed and cannot be transmitted in the SIW cavity.

4. The balanced filter cross-junction with high common-mode rejection of claim 3, wherein the four SIW resonant cavities surrounding the third SIW cavity are the SIW cavity , the second SIW cavity, the fourth SIW cavity and the fifth SIW cavity respectively, the four feeding microstrip lines on the dielectric substrate and the third substrate form four pairs of differential ports, the differential port, the second differential port, the third differential port and the fourth differential port respectively, and when the differential port and the second differential port are excited by differential signals, the coaxially arranged SIW cavity , the second SIW cavity and the third SIW cavity can only excite TE₂₀₁Molding; when the third differential port and the fourth differential port are excited by differential signals, the SIW cavity three, the SIW cavity four and the SIW cavity five which are coaxially arranged can only excite TE₁₀₂And (5) molding.

5. A balanced filter crossover junction with high common mode rejection according to claim 1, wherein: the four SIW resonant cavities surrounding the third SIW cavity are smaller than the third SIW cavity in size.

6. The balanced filtering cross-junction with high common-mode rejection of claim 1, wherein the outer end of each feeding microstrip line extends to the outer wall of the dielectric substrate or the dielectric substrate III and is connected to the corresponding balanced port, the inner end of each feeding microstrip line is open-circuited, each rectangular slot is perpendicular to and symmetrical with the corresponding feeding microstrip line, and the open-circuited inner end of each feeding microstrip line extends out of the corresponding rectangular slot.

7. The balanced filter cross-junction with high common-mode rejection of claim 6, wherein: the coupling energy between the feed microstrip line and the rectangular slot is adjusted by adjusting the distance between the open-circuit inner end of the feed microstrip line and the rectangular slot.

8. A balanced filter crossover junction with high common-mode rejection according to claim 1 or 6, characterized in that: the working frequency of the balanced filtering cross junction is adjusted by adjusting the side sizes of the five SIW resonant cavities.

9. A balanced filter crossover junction with high common mode rejection according to claim 8, wherein: the working bandwidth of the balanced filter cross-over junction is adjusted by adjusting the length size of the coupling window.

10. A balanced filter crossover junction with high common mode rejection according to claim 9, wherein: and adjusting the external quality factor of the balanced filter cross junction by adjusting the length and the width of the rectangular gap.

Technical Field

The invention relates to the technical field of balanced filters, in particular to balanced filter cross junctions with high common-mode rejection.

Background

In modern wireless communication systems, balancing devices are receiving increasing attention because they can effectively suppress both ambient noise and noise within the system. Cross junctions are components often used in monolithic microwave integrated circuits that allow two signals to cross each other without interfering with each other. And the filter is an indispensable device of the communication system equipment. With the continuous development of wireless communication technology, the integration degree of the system is higher and higher, and the miniaturization becomes an inevitable trend. And the filter and the cross junction are cooperatively designed, so that the volume of the device can be effectively reduced, and the integration level of the system is improved. Currently, researchers have designed a number of balanced cross junctions based on microstrip lines. However, since the microstrip transmission line has large loss at high frequency, these balanced cross-junctions are difficult to apply to the higher microwave band, and high common mode rejection (noise rejection) cannot be achieved in a wide frequency band.

The Substrate Integrated Waveguide (SIW) is similar to the traditional metal waveguide structure, and the propagation characteristic is basically , so the substrate integrated waveguide has the characteristics of high Q value, strong transmission capability and the like, meanwhile, the structure of the substrate integrated waveguide is also similar to a microstrip structure, and has the characteristics of small volume, light weight, low cost, easy processing, high integration level and the like.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide balanced filter cross-junctions with high common mode rejection based on single-layer Substrate Integrated Waveguide (SIW) and multi-layer microstrip conversion, which have compact structure, high isolation and high common mode rejection performance, and can be applied to higher centimeter wave and millimeter wave frequency bands.

In order to solve the technical problems, the invention adopts the technical scheme that:

balanced filter cross junctions with high common mode rejection comprise a dielectric substrate , a metal surface , a dielectric substrate II, a metal surface II and a dielectric substrate III which are coaxially arranged from top to bottom in sequence.

Five square SIW resonant cavities are arranged on the second dielectric substrate, wherein SIW resonant cavities are positioned in the center of the second dielectric substrate and are the third SIW resonant cavities, the other four SIW resonant cavities are identical in size and are arranged around the third SIW resonant cavity in a surrounding mode, and energy coupling between the four side walls of the third SIW resonant cavity and the adjacent SIW resonant cavities is achieved through coupling windows respectively.

Four feed microstrip lines are arranged on the dielectric substrate and the dielectric substrate III, four rectangular gaps are arranged on the metal surface and the metal surface II, and the rectangular gaps are used for realizing the coupling between the feed microstrip lines and the SIW resonant cavity.

The coupling window is positioned in the center of the side edges of the three opposite sides of the SIW cavity.

Forming third-order balanced band-pass filters with five SIW resonators, using pairs of orthogonal degenerate modes TE in the SIW resonators₁₀₂And TE₂₀₁Modulo, TE when differential signal excitation is achieved₁₀₂And TE₂₀₁The normal excitation of the modes does not interfere with each other. While the common mode signal is suppressed and cannot be transmitted in the SIW cavity.

Four SIW resonant cavities surrounding the third SIW cavity are an SIW cavity , an SIW cavity II, an SIW cavity IV and an SIW cavity V, four feeding microstrip lines on the dielectric substrate and the dielectric substrate III form four pairs of differential ports, namely a differential port, a second differential port, a third differential port and a fourth differential port, respectively, when the differential port and the second differential port are excited by differential signals, the SIW cavity , the SIW cavity II and the SIW cavity III which are coaxially arranged can only excite TE₂₀₁And (5) molding. When the third differential port and the fourth differential port are excited by differential signals, the SIW cavity three, the SIW cavity four and the SIW cavity five which are coaxially arranged can only excite TE₁₀₂And (5) molding.

The four SIW resonant cavities surrounding the third SIW cavity are smaller than the third SIW cavity in size.

The outer end of each feed microstrip line extends to the outer side wall of the dielectric substrate or the dielectric substrate III and is connected with the corresponding balance port, the inner end of each feed microstrip line is open-circuited, each rectangular slot is perpendicular to the corresponding feed microstrip line and is symmetrical with the corresponding feed microstrip line, and the open-circuited inner end of each feed microstrip line extends out of the corresponding rectangular slot.

The coupling energy between the feed microstrip line and the rectangular slot is adjusted by adjusting the distance between the open-circuit inner end of the feed microstrip line and the rectangular slot.

The working frequency of the balanced filtering cross junction is adjusted by adjusting the side sizes of the five SIW resonant cavities.

The working bandwidth of the balanced filter cross-over junction is adjusted by adjusting the length size of the coupling window.

And adjusting the external quality factor of the balanced filter cross junction by adjusting the length and the width of the rectangular gap.

The invention has the following beneficial effects:

1. it is suitable for the higher centimeter wave and millimeter wave frequency range. The invention adopts the SIW transmission line with high quality factor as the main structure, so the invention can be applied to higher frequency band, and the preferred frequency band is 10-40 GHz.

2. The cross transmission of two paths of differential signals can be realized, the isolation is high, and filtering effects of three-order band-pass response are generated for the differential signals.

3. The method can realize a good suppression effect on the common mode noise in a very wide (0-60GHz) frequency band, obviously improve the signal-to-noise ratio in a communication system and improve the communication quality. Under common-mode signal excitation, the central symmetry plane of the SIW cavity can be equivalent to the PMC plane, while the upper and lower ground planes of the SIW cavity can be considered as the PEC planes. According to the boundary condition of the PEC-PMC, common-mode signals cannot be transmitted in the SIW at the moment, and therefore high common-mode rejection effect is obtained.

Drawings

Fig. 1 shows a schematic structural diagram of a dielectric substrate used in the present invention.

Fig. 2 shows a schematic three-dimensional structure diagram of balanced filter cross-junctions with high common-mode rejection according to the present invention.

Fig. 3 shows a top view of balanced filter cross-junctions with high common mode rejection according to the present invention.

Fig. 4a shows the electric field distribution of balanced filter cross-junctions with high common mode rejection under differential mode excitation.

Fig. 4b shows the electric field distribution of balanced filter cross-junctions with high common mode rejection under common mode excitation.

Fig. 5 shows the scattering parameter simulation and test results of balanced filter cross-junctions with high common mode rejection according to the present invention.

Among them are:

10. the power supply comprises a medium substrate , 11 feed microstrip lines, S1 a medium substrate, S2 an upper metal layer, S3 a lower metal layer, a port1 an upper balanced port, a port2 an upper second balanced port, a port3 an upper third balanced port and a port4 an upper fourth balanced port;

20. metal surfaces , 21, rectangular slots;

30. a second dielectric substrate, 31, a SIW cavity , 32, a second SIW cavity, 33, a third SIW cavity, 331, a coupling window, 34, a fourth SIW cavity, 35, a fifth SIW cavity, 36, a metal through hole;

40. a second metal surface;

50. a third dielectric substrate, a port1 ', a lower balanced port, a port 2', a lower second balanced port, a port3 ', a lower third balanced port, and a port 4', a lower fourth balanced port.

Detailed Description

The invention is described in further detail with reference to the drawings and the detailed description of the preferred embodiment.