A miniaturized SIW filter crossover junction that can be shared by all cavities

Abstract

The present invention discloses a miniaturized SIW filter cross junction that can be shared by all cavities. From input to output, it includes the first to third unit structures, and the adjacent structures are connected by two coupled transmission lines; in each SIW circular cavity, two filter cross junction channels use TE 201 Die and TE 102 Mode, due to the orthogonality of the two modes, the two passbands have natural isolation; by setting the external quality factor and coupling coefficient of the two channels, each passband has a bandpass filtering characteristic; the linear metallized through-hole array in each SIW circular cavity perturbs the strongest point of the transmission electric field of the filter cross junction channel 2, so that its passband center frequency shifts to high frequency, and at the zero point of the transmission electric field of the filter cross junction channel 1, it has almost no effect on the passband of the filter cross junction channel 1. The signal transmission electric field modes of the two passbands are completely orthogonal, do not affect each other, and have high isolation; the two passband designs are completely independent, which is convenient for designing the center frequency of each passband.

Description

Technical Field

[0001] The invention belongs to the field of microwave technology and relates to a substrate integrated waveguide (SIW) filter cross junction, in particular to a miniaturized SIW filter cross junction that can be shared by all cavities. Background Art

[0002] Microwave cross junctions and filters are both important components in wireless communication systems. In order to achieve functions such as signal crossover and filtering at the same time, the cross junction and filter can be cascaded traditionally, but this solution has large circuit size and insertion loss. Therefore, people began to try to directly integrate the filtering function into the microwave cross junction, thereby realizing a new multifunctional device called filter cross junction.

[0003] As we all know, substrate integrated waveguide (SIW) has been widely used in microwave high frequency bands due to its fully enclosed and low loss characteristics. Among them, a variety of SIW-based filtering crossover junctions have also been proposed. Their basic idea is to use the orthogonal degenerate modes (TE) in the SIW rectangular cavity. 102 and TE 201 ) to achieve signal cross transmission and channel isolation, and at the same time use it as a shared cavity to build a filtering function with other cavities surrounding it. However, since this structure only shares the middle cavity, in order to achieve a 2N+1 (N is a natural number) order filter cross junction, 4N+1 cavities are required, which greatly increases the size of the device.

[0004] In order to overcome the shortcomings of the prior art, the present invention proposes a miniaturized SIW filter cross junction that can be shared by all cavities. For a 2N+1 order filter cross junction, only 2N+1 cavities need to be used, which greatly reduces the device area. The designs of the two passbands are independent of each other, and the design complexity is low. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and provide a miniaturized SIW filter crossover junction that can be shared by all cavities.

[0006] The present invention adopts the following technical solution:

[0007] A miniaturized SIW filter crossover junction that can be shared by all cavities is a centrally symmetrical structure, including first to third unit structures from input to output, and adjacent structures are connected by two coupled transmission lines;

[0008] The first unit structure comprises a first SIW circular cavity (2), a first input port (1), a second input port (11), and a first linear metallized through hole array perturbation (3); the first input port (1) and the second input port (11) face the center of the first SIW circular cavity (2); the center of the first linear metallized through hole array perturbation (3) coincides with the center of the first SIW circular cavity (2); and first rectangular gaps are provided on both sides of the first input port (1) and the second input port (11);

[0009] The second unit structure comprises a second SIW circular cavity (5) and a second linear metallized through hole array perturbation (6); the second linear metallized through hole array perturbation (6) coincides with the center of the second SIW circular cavity (5);

[0010] The third unit structure comprises a third SIW circular cavity (8), a third linear metallized through hole array perturbation (9), a first output port (10), and a second output port (14); the first output port (10) and the second output port (14) face the center of the third SIW circular cavity (8); the center of the third linear metallized through hole array perturbation (9) coincides with the center of the third SIW circular cavity (8); and second rectangular gaps are provided on both sides of the first output port (10) and the second output port (14);

[0011] The centers of the first SIW circular cavity (2), the second SIW circular cavity (5), and the third SIW circular cavity (8) are located on the same straight line;

[0012] The first SIW circular cavity (2) and the second SIW circular cavity (5) are connected via a first coupling transmission line (4) and a third coupling transmission line (12);

[0013] The second SIW circular cavity (5) and the third SIW circular cavity (8) are connected via a second coupling transmission line (7) and a fourth coupling transmission line (13);

[0014] A third rectangular slit is provided on both sides of the connection end of the first coupling transmission line (4) located at the first SIW circular cavity (2), and a fourth rectangular slit is provided on both sides of the connection end of the third coupling transmission line (12) located at the first SIW circular cavity (2);

[0015] The first coupling transmission line (4) is provided with fifth rectangular slots on both sides of the connection end of the second SIW circular cavity (5), and the third coupling transmission line (12) is provided with sixth rectangular slots on both sides of the connection end of the second SIW circular cavity (5);

[0016] The second coupling transmission line (7) is provided with a seventh rectangular slot on both sides of the connection end of the second SIW circular cavity (5), and the fourth coupling transmission line (13) is provided with an eighth rectangular slot on both sides of the connection end of the second SIW circular cavity (5);

[0017] A ninth rectangular slot is provided on both sides of the connection end of the second coupling transmission line (7) located at the third SIW circular cavity (8), and a tenth rectangular slot is provided on both sides of the connection end of the fourth coupling transmission line (13) located at the third SIW circular cavity (8);

[0018] Preferably, the angle between the initial positions of the first input port (1) and the second input port (11) is 90°;

[0019] Preferably, the initial position of the third rectangular slot on both sides of the first coupling transmission line (4) is arranged in parallel with the first input port (1); the initial position of the fourth rectangular slot on both sides of the third coupling transmission line (12) is arranged in parallel with the second input port (11); the initial position of the fifth rectangular slot on both sides of the first coupling transmission line (4) is arranged in parallel with the seventh rectangular slot on both sides of the second coupling transmission line (7); the initial position of the sixth rectangular slot on both sides of the third coupling transmission line (12) is arranged in parallel with the eighth rectangular slot on both sides of the fourth coupling transmission line (13); the initial position of the ninth rectangular slot on both sides of the second coupling transmission line (7) is arranged in parallel with the first output port (10); and the initial position of the tenth rectangular slot on both sides of the fourth coupling transmission line (13) is arranged in parallel with the second output port (14);

[0020] Preferably, the first SIW circular cavity (2), the second SIW circular cavity (5), and the third SIW circular cavity (8) are composed of a plurality of periodically arranged metallized through holes; a window is provided in the portion where the second SIW circular cavity (5) is connected to the first SIW circular cavity (2) and the third SIW circular cavity (8), and the window is provided with no metallized through hole; the first input port (1), the second input port (11), the first coupled transmission line (4), the third coupled transmission line (12), the second coupled transmission line (7), the fourth coupled transmission line (13), the first output port (10), and the second output port (14) are located in the SIW circular cavity portion where no metallized through hole is provided;

[0021] Preferably, the angle between the initial positions of the rectangular gaps on both sides of different SIW circular cavities located on the same coupled transmission line is 90°;

[0022] Preferably, since the straight line where the first input port (1) and the second input port (11) are located does not coincide with the straight line where the electric field zero point in the first SIW circular cavity (2) is located, after optimization, the first input port (1), the second input port (11), the first output port (10), the second output port (14), the first coupled transmission line (4), the second coupled transmission line (7), the third coupled transmission line (12), the fourth coupled transmission line (13) and the first linear metallized through hole array perturbation (3), the second linear metallized through hole array perturbation (6) and the third linear metallized through hole array perturbation (9) are rotated a certain degree relative to the center of the first SIW circular cavity (2), the second SIW circular cavity (5) and the third SIW circular cavity (8);

[0023] Preferably, the first input port (1), the second input port (11), the first output port (10), and the second output port (14) are all fed by a 50-ohm microstrip line;

[0024] Preferably, the line widths of the first coupled transmission line (4) and the fourth coupled transmission line (13) are the same; the line widths of the second coupled transmission line (7) and the third coupled transmission line (12) are the same;

[0025] Preferably, the width and length of the third rectangular gap, the fifth rectangular gap, the eighth rectangular gap, and the tenth rectangular gap are the same; the width and length of the fourth rectangular gap, the sixth rectangular gap, the seventh rectangular gap, and the ninth rectangular gap are the same;

[0026] Preferably, the first input port (1), the first coupled transmission line (4), the third coupled transmission line (12), and the first output port (10) form a filtering cross-junction channel 1;

[0027] A second filtering cross-junction channel 2 is formed by the second input port (11), the second coupled transmission line (7), the fourth coupled transmission line (13), and the second output port (14);

[0028] The linear metallized through hole array perturbation in each SIW circular cavity is located at the strongest point of the transmission electric field of the second filtering cross junction channel and the zero point of the transmission electric field of the first filtering cross junction channel.

[0029] The present invention utilizes SIW to perturb the TE of the circular cavity 201 TE 102The invention discloses a novel filter cross-junction, wherein the filter cross-junction is constructed by using a plurality of modules; the center frequency of one of the passbands of the filter cross-junction can be controlled by adjusting the length c of the first linear metallized through hole array perturbation (3), the second linear metallized through hole array perturbation (6) and the third linear metallized through hole array perturbation (9); the bandwidth of the two passbands of the filter cross-junction can be controlled by adjusting the width w2 and w3 of the first coupled transmission line (4), the second coupled transmission line (7), the third coupled transmission line (12) and the fourth coupled transmission line (13); the external quality factor of the filter cross-junction can be controlled by adjusting the length l1 and the width d1 of the first rectangular slot; the coupling coefficient of the filter cross-junction can be controlled by adjusting the length l2, l3 and the width d2, d3 of the slots on both sides of the coupled transmission line; according to the required filtering bandwidth, by setting the external quality factor and the coupling coefficient that satisfy the coupling matrix theory, the cross-junction can have a bandpass filtering characteristic in each passband; the invention has great flexibility in design.

[0030] Working principle:

[0031] Filter cross-junction channel 1: A signal is input from the first input port (1), enters the first coupled transmission line (4), then enters the third coupled transmission line (12), and finally output from the first output port (10).

[0032] Filter cross-junction channel 2: The signal is input from the second input port (11), enters the second coupled transmission line (7), then enters the fourth coupled transmission line (13), and finally output from the second output port (14).

[0033] The electric field modes used in the two filter cross-junction channels in each SIW circular cavity are TE 201 TE 102 Mode, due to the orthogonality of the two modes, the two passbands have natural isolation; at the same time, by setting the external quality factor and coupling coefficient of the two channels respectively, the cross junction can have bandpass filtering characteristics in each passband; the linear metallized through-hole array in each SIW circular cavity perturbs the strongest point of the transmission electric field of the filtering cross junction channel two, so that the center frequency of its passband shifts to high frequency, and at the zero point of the transmission electric field of the filtering cross junction channel one, it has almost no effect on the passband of the filtering cross junction channel one.

[0034] The present invention has the following advantages:

[0035] (1) All SIW cavities of the two channels of the cross junction are shared, which greatly reduces the area compared with the traditional scheme;

[0036] (2) The electric field modes of the signal transmission in the two passbands are completely orthogonal, and the two do not affect each other, with high isolation;

[0037] (3) The two passband designs of the cross junction are completely independent, and the center frequency of each passband can be easily designed. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is an overall structural diagram of a miniaturized SIW filter crossover junction that can be shared by all cavities;

[0039] Figure 2 This is the electric field diagram of the cross-junction channel one of a miniaturized SIW filter that can be shared by all cavities;

[0040] Figure 3 It is the S-parameter simulation result of a miniaturized SIW filter crossover junction that can be shared by all cavities;

[0041] Markings in the figure: first input port 1, first SIW circular cavity 2, first linear metallized through hole array perturbation 3, first coupled transmission line 4, second SIW circular cavity 5, second linear metallized through hole array perturbation 6, second coupled transmission line 7, third SIW circular cavity 8, third linear metallized through hole array perturbation 9, first output port 10, second input port 11, third coupled transmission line 12, fourth coupled transmission line 13, second output port 14. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings.

[0043] like Figure 1 As shown, a miniaturized SIW filter crossover junction that can be shared by all cavities is a centrally symmetrical structure, including: a first SIW circular cavity 2, a second SIW circular cavity 5, a third SIW circular cavity 8, a first linear metallized through hole array perturbation 3, a second linear metallized through hole array perturbation 6, a third linear metallized through hole array perturbation 9, a first coupled transmission line 4, a second coupled transmission line 7, a third coupled transmission line 12, a fourth coupled transmission line 13, a first input port 1, a second input port 11, a first output port 10, and a second output port 14;

[0044] The centers of the first linear metallized through hole array perturbation 3, the second linear metallized through hole array perturbation 6, and the third linear metallized through hole array perturbation 9 coincide with the centers of the first SIW circular cavity 2, the second SIW circular cavity 5, and the third SIW circular cavity 8, respectively, and the initial position of the first linear metallized through hole array perturbation 3 is located in the same straight line as the first input port 1; the initial position of the second linear metallized through hole array perturbation 6 is located in the same straight line as the portion of the first coupling transmission line 4 located in the second SIW circular cavity 5; the initial position of the third linear metallized through hole array perturbation 9 is located in the same straight line as the first output port 10;

[0045] The first linear metallized through hole array perturbation 3 , the second linear metallized through hole array perturbation 6 , and the third linear metallized through hole array perturbation 9 are all composed of two non-contacting metallized through holes.

[0046] The first input port 1 is parallel to the initial position of the first coupling transmission line 4 in the first SIW circular cavity 2 and is located on the same diameter of the first SIW circular cavity 2; the initial position of the first coupling transmission line 4 in the first SIW circular cavity 2 is perpendicular to the initial position of the first coupling transmission line 4 in the second SIW circular cavity 5;

[0047] The second input port 11 is initially perpendicular to the first input port 1; the second coupling transmission line 12 and the first coupling transmission line 4 are initially perpendicular to each other in the first SIW circular cavity 2; the second coupling transmission line 12 and the first coupling transmission line 4 are initially perpendicular to each other in the second SIW circular cavity 5. The second coupling transmission line 7 and the fourth coupling transmission line 13 are initially perpendicular to each other in the second SIW circular cavity 5. The second coupling transmission line 7 and the fourth coupling transmission line 13 are initially perpendicular to each other in the third SIW circular cavity 8.

[0048] In this example, the dielectric substrate is a microwave plate material with a dielectric constant of 2.2 and a thickness of 0.508 mm.

[0049] Table 1 Dimensional parameters (unit: mm)

[0050] <![CDATA[l1]]> <![CDATA[d1]]> <![CDATA[w1]]> <![CDATA[l2]]> <![CDATA[d2]]> <![CDATA[w2]]> 4.48 0.35 1.57 3.91 0.2 1.8 <![CDATA[l3]]> <![CDATA[d3]]> <![CDATA[w3]]> c r 3.91 0.2 1.8 3.6 12.66

[0051] Figure 2 This is an electric field diagram of a miniaturized SIW filter crossover junction that can be shared by all cavities. When a signal enters from the first input port (1), a TE is excited in the first SIW circular cavity 2. 102 The mode is transmitted to the second SIW circular cavity 5 through the first coupling transmission line 4 to excite the TE 201 The mode is then transmitted by the second coupling transmission line 7 to the third SIW circular cavity 8 to excite the TE 102 The second output port (14) is located in the third SIW circular cavity 8. 102 The electromagnetic distribution zero point of the mode is zero, so there is no energy output. At the same time, due to the existence of the linear metallized through-hole array perturbation, the electric field perturbation causes its frequency to shift to high frequency, realizing the characteristic of adjustable channel-center frequency.

[0052] Figure 3 The S-parameter simulation results of a miniaturized SIW filter crossover junction that can be shared by all cavities. The center frequencies of the two passbands of the crossover junction are 10 GHz and 10.44 GHz respectively. The 3-dB bandwidth of both channels is 310 MHz. In both passbands, the return loss |S11 | and |S 44 The amplitude of | is less than -20dB, and the insertion loss |S 21 | and |S 34 The amplitude of | is better than -3dB, and the isolation between the first input port 1 and the second input port 11 and the second output port 14 |S 31 | and |S 41 |Both are better than -20dB.

[0053] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A miniaturized SIW filter crossover junction that can be shared by all cavities, with a central symmetrical structure, characterized by From input to output, it includes first to third unit structures, and adjacent structures are connected by two coupled transmission lines; The first unit structure comprises a first SIW circular cavity (2), a first input port (1), a second input port (11), and a first linear metallized through hole array perturbation (3); the first input port (1) and the second input port (11) face the center of the first SIW circular cavity (2); the center of the first linear metallized through hole array perturbation (3) coincides with the center of the first SIW circular cavity (2); and first rectangular gaps are provided on both sides of the first input port (1) and the second input port (11); The second unit structure comprises a second SIW circular cavity (5) and a second linear metallized through hole array perturbation (6); the second linear metallized through hole array perturbation (6) coincides with the center of the second SIW circular cavity (5); The third unit structure comprises a third SIW circular cavity (8), a third linear metallized through hole array perturbation (9), a first output port (10), and a second output port (14); the first output port (10) and the second output port (14) face the center of the third SIW circular cavity (8); the center of the third linear metallized through hole array perturbation (9) coincides with the center of the third SIW circular cavity (8); and second rectangular gaps are provided on both sides of the first output port (10) and the second output port (14); The centers of the first SIW circular cavity (2), the second SIW circular cavity (5), and the third SIW circular cavity (8) are located on the same straight line; The first SIW circular cavity (2) and the second SIW circular cavity (5) are connected via a first coupling transmission line (4) and a third coupling transmission line (12); The second SIW circular cavity (5) and the third SIW circular cavity (8) are connected via a second coupling transmission line (7) and a fourth coupling transmission line (13); A third rectangular slit is provided on both sides of the connection end of the first coupling transmission line (4) located at the first SIW circular cavity (2), and a fourth rectangular slit is provided on both sides of the connection end of the third coupling transmission line (12) located at the first SIW circular cavity (2); The first coupling transmission line (4) is provided with fifth rectangular slots on both sides of the connection end of the second SIW circular cavity (5), and the third coupling transmission line (12) is provided with sixth rectangular slots on both sides of the connection end of the second SIW circular cavity (5); The second coupling transmission line (7) is provided with a seventh rectangular slot on both sides of the connection end of the second SIW circular cavity (5), and the fourth coupling transmission line (13) is provided with an eighth rectangular slot on both sides of the connection end of the second SIW circular cavity (5); A ninth rectangular slot is provided on both sides of the connection end of the second coupling transmission line (7) located at the third SIW circular cavity (8), and a tenth rectangular slot is provided on both sides of the connection end of the fourth coupling transmission line (13) located at the third SIW circular cavity (8).

2. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The angle between the initial positions of the first input port (1) and the second input port (11) is 90°.

3. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The initial position of the third rectangular slot on both sides of the first coupling transmission line (4) is arranged in parallel with the first input port (1); the initial position of the fourth rectangular slot on both sides of the third coupling transmission line (12) is arranged in parallel with the second input port (11); the initial position of the fifth rectangular slot on both sides of the first coupling transmission line (4) is arranged in parallel with the seventh rectangular slot on both sides of the second coupling transmission line (7); the initial position of the sixth rectangular slot on both sides of the third coupling transmission line (12) is arranged in parallel with the eighth rectangular slot on both sides of the fourth coupling transmission line (13); the initial position of the ninth rectangular slot on both sides of the second coupling transmission line (7) is arranged in parallel with the first output port (10); and the initial position of the tenth rectangular slot on both sides of the fourth coupling transmission line (13) is arranged in parallel with the second output port (14).

4. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The first SIW circular cavity (2), the second SIW circular cavity (5), and the third SIW circular cavity (8) are composed of a plurality of periodically arranged metallized through holes; a window is provided in the portion where the second SIW circular cavity (5) is connected to the first SIW circular cavity (2) and the third SIW circular cavity (8), and the window is provided with no metallized through hole; and the first input port (1), the second input port (11), the first coupled transmission line (4), the third coupled transmission line (12), the second coupled transmission line (7), the fourth coupled transmission line (13), the first output port (10), and the second output port (14) are located in the SIW circular cavity portion where no metallized through hole is provided.

5. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The angle between the initial positions of the rectangular gaps located on the same coupled transmission line and on both sides of different SIW circular cavities is 90°.

6. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The straight line where the first input port (1) and the second input port (11) are located does not coincide with the straight line where the electric field zero point in the first SIW circular cavity (2) is located.

7. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The line widths of the first coupled transmission line (4) and the fourth coupled transmission line (13) are the same; the line widths of the second coupled transmission line (7) and the third coupled transmission line (12) are the same.

8. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that The width and length of the third rectangular gap, the fifth rectangular gap, the eighth rectangular gap and the tenth rectangular gap are the same; the width and length of the fourth rectangular gap, the sixth rectangular gap, the seventh rectangular gap and the ninth rectangular gap are the same.

9. A miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that A filtering cross-junction channel 1 is formed by a first input port (1), a first coupled transmission line (4), a third coupled transmission line (12), and a first output port (10); A second filtering cross-junction channel 2 is formed by the second input port (11), the second coupled transmission line (7), the fourth coupled transmission line (13), and the second output port (14); The linear metallized through-hole array perturbation in each SIW circular cavity is located at the strongest point of the transmission electric field of the second filtering cross junction channel and the zero point of the transmission electric field of the first filtering cross junction channel.

10. The miniaturized SIW filter crossover junction that can be shared by all cavities according to claim 1, characterized in that: TE using SIW circular cavity 201 Die and TE 102 The modules respectively construct two passbands of the filter cross junction; by adjusting the length c of the first linear metallized through hole array perturbation (3), the second linear metallized through hole array perturbation (6), and the third linear metallized through hole array perturbation (9), the center frequency of one of the passbands of the filter cross junction is controlled; By adjusting the widths w2 and w3 of the first coupled transmission line (4), the second coupled transmission line (7), the third coupled transmission line (12), and the fourth coupled transmission line (13), the bandwidths of the two passbands of the filter crossover junction are controlled respectively; By adjusting the length l1 and width d1 of the first rectangular gap, the external quality factor of the filter cross junction is controlled; By adjusting the length and width of the gaps on both sides of the coupled transmission line located in the same SIW circular cavity, the coupling coefficient of the filter cross junction is controlled; A filtering cross-junction channel 1 is formed by a first input port (1), a first coupled transmission line (4), a third coupled transmission line (12), and a first output port (10); A second filtering cross-junction channel 2 is formed by the second input port (11), the second coupled transmission line (7), the fourth coupled transmission line (13), and the second output port (14); The linear metallized through-hole array perturbation in each SIW circular cavity is located at the strongest point of the transmission electric field of the second filtering cross junction channel and the zero point of the transmission electric field of the first filtering cross junction channel.

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