A frequency and amplitude independently controllable SIW filter based on CT topology

Abstract

A frequency and amplitude independently adjustable SIW filter based on CT topology, comprising a top metal layer, a dielectric substrate and a bottom metal layer arranged in sequence from top to bottom; a metallized through hole array is vertically penetrated through the dielectric substrate, the metallized through hole is connected with the top metal layer and the bottom metal layer, and three resonant cavities distributed in the form of CT topology are formed through the metallized through hole array, and a perturbation metallized through hole is respectively arranged at the center of the three resonant cavities, and the three resonant cavities are coupled to each other through an inductive coupling window composed of the metallized through hole; three annular grooves are arranged at the top metal layer corresponding to the center of the three resonant cavities, and an adjustable varactor group is arranged on the top metal layer; an input and output feeding port is arranged on the bottom metal layer, and three annular graphene layers are arranged at the bottom metal layer corresponding to the three annular grooves. The present invention simultaneously realizes that the frequency and transmission amplitude of the SIW filter are independently adjustable.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave devices, and in particular relates to a frequency and amplitude independently controllable SIW filter based on CT (cascaded triplet) topology. Background Art

[0002] Emerging wireless communications and radar systems have increasing requirements for tunable radio frequency (RF) front ends that can respond to different spectral environments. Microwave reconfigurable filters are an important component of future multifunctional RF front ends due to their dynamic frequency tuning capabilities. Among the many studies on reconfigurable filters, coaxial SIW resonators are always the first choice for tunable filters due to their more compact structure, continuous tuning range, and low-cost manufacturing process. Tunable microwave attenuators are also important components in various communication systems for adjusting signals to different levels. In the microwave band, graphene-based tunable attenuators have attracted much attention due to graphene's unique electrically tunable omnidirectional resistance.

[0003] With the development of modern microwave devices, versatility and high integration are increasingly valued. The versatility of devices is an effective way to reduce circuit size and enhance versatility. Bandpass filters and attenuators are widely combined for certain specific applications, including automatic level or gain control circuits in communications and radar systems. Existing microwave devices focus on multi-function or single reconfiguration, but none of them can achieve simultaneous and independent tuning of filtering and attenuation responses. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned problems in the prior art and provide a frequency and amplitude independently adjustable SIW filter based on CT topology to realize a multi-reconfigurable RF device with tunable filtering and attenuation functions.

[0005] In order to achieve the above object, the present invention has the following technical solutions:

[0006] A frequency and amplitude independently adjustable SIW filter based on CT topology, comprising a top metal layer, a dielectric substrate and a bottom metal layer arranged in sequence from top to bottom; a plurality of metallized through holes are vertically penetrated through the dielectric substrate to form a metallized through hole array, the metallized through holes are connected with the top metal layer and the bottom metal layer, and three resonant cavities distributed in the form of CT topology are formed through the metallized through hole array, a perturbation metallized through hole is respectively arranged at the center of the three resonant cavities, and the three resonant cavities are mutually coupled through an inductive coupling window, and the inductive coupling window is composed of the metallized through hole The perturbation metallized through hole and the metallized through hole of the inductive coupling window penetrate the dielectric substrate and are connected to the top metal layer and the bottom metal layer; the top metal layer is provided with three annular grooves corresponding to the positions of the centers of the three resonant cavities, and an adjustable variable capacitance tube group is provided on the top metal layer, one end of the adjustable variable capacitance tube group is connected to the top metal layer on the inner side of the annular groove and is connected to the bottom metal layer through the perturbation metallized through hole, and the other end is connected to the top metal layer on the outer side of the annular groove; the bottom metal layer is provided with input and output feeding ports, and three annular graphene layers are provided on the bottom metal layer corresponding to the positions of the three annular grooves.

[0007] As a preferred solution, the three resonant cavities distributed in the form of CT topology are three intersecting circular cavities or polygonal cavities, the three resonant cavities have the same shape and are centrally symmetrical, and two adjacent resonant cavities share part of the cavity wall.

[0008] As a preferred solution, two input and output feeding ports are arranged along a straight line, and the input and output feeding ports include a grounded coplanar waveguide and a connected arcuate slot line. The arcuate slot lines of the two input and output feeding ports are surrounded by the outside of the annular graphene layer of the two resonant cavities. The grounded coplanar waveguide leads the arcuate slot line to the two side edges of the bottom metal layer. The dielectric substrate is opened at the position of the resonant cavity corresponding to the grounded coplanar waveguide, and metallized through holes are arranged on both sides of the grounded coplanar waveguide to connect with the metallized through hole array.

[0009] As a preferred solution, the input and output feeding ports are led out from the midpoints of the side walls of the two resonant cavities, and the structures of the two input and output feeding ports are mirror-symmetrical; the arc-shaped slot line is composed of continuous curves or straight lines.

[0010] As a preferred solution, the inductive coupling window is composed of a cylindrical, cube or rectangular metallized through hole.

[0011] As a preferred solution, the perturbation metallized through hole is a cylindrical, cubic or rectangular metallized through hole.

[0012] As a preferred solution, the annular groove is circular or polygonal, and the adjustable varactor group is composed of a plurality of identical varactors.

[0013] As a preferred solution, the annular graphene layer is circular or polygonal, and the shape of the annular graphene layer is the same as the annular groove.

[0014] As a preferred solution, the annular graphene layer is arranged in the bottom metal layer, and the thickness is the same as the thickness of the bottom metal layer.

[0015] As a preferred solution, the capacitance value of the adjustable varactor group is changed, the sheet resistance of the annular graphene layer remains unchanged, and the center frequency of the filter is controlled to move, so that the transmission amplitude at the same center frequency remains unchanged;

[0016] The capacitance value of the adjustable varactor group remains unchanged, the sheet resistance of the annular graphene layer remains changed, and the center frequency of the filter is controlled to remain unchanged, and the transmission amplitude at the center frequency changes.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] By arranging an adjustable varactor group on the top metal layer and an annular graphene layer on the bottom metal layer, a SIW filter with independently adjustable frequency and transmission amplitude is realized, and the filter has a more compact size and richer functions. In the SIW filter structure with independently adjustable frequency and transmission amplitude of the present invention, three resonant cavities distributed in the form of CT (cascaded triplet) topology are formed on the dielectric substrate through a metallized through-hole array. Without the additional use of a cross-coupling structure, a transmission zero point is introduced at the high end of the filter passband, thereby improving the selectivity and out-of-band suppression of the filter. The SIW filter with independently adjustable frequency and transmission amplitude of the present invention only changes the capacitance value C of the adjustable varactor group when regulating the center frequency. v1 It can be achieved that the regulation of the transmission amplitude only changes the sheet resistance R of the annular graphene layer. g It can be realized, and the control method is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A three-dimensional structure diagram of a SIW filter with independently adjustable frequency and amplitude based on a CT topology according to an embodiment of the present invention;

[0020] Figure 2 A top view of the top metal layer structure of an embodiment of the present invention;

[0021] Figure 3 A top view of the bottom metal layer structure of an embodiment of the present invention;

[0022] Figure 4 The return loss |S11| simulation result diagram of the filter according to the embodiment of the present invention;

[0023] Figure 5Insertion loss |S21| simulation result diagram of the filter according to the embodiment of the present invention;

[0024] Figure 6 Insertion loss |S21| simulation result diagram of transmission adjustability of the filter of the embodiment of the present invention at three center frequencies;

[0025] In the accompanying drawings: 1-top metal layer; 2-dielectric substrate; 3-bottom metal layer; 4-metallized through hole array; 5-adjustable varactor group; 6-annular graphene layer; 7-first resonant cavity; 8-second resonant cavity; 9-third resonant cavity; 10-perturbation metallized through hole; 11-annular groove; 12-input and output feeding ports; 13-grounded coplanar waveguide; 14-arc slot line; 15-inductive coupling window. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0027] See also Figure 1 An embodiment of the present invention provides a frequency and amplitude independently controllable SIW filter based on CT topology, comprising a top metal layer 1, a dielectric substrate 2 and a bottom metal layer 3 arranged in sequence from top to bottom.

[0028] A plurality of metallized through holes are vertically formed on the dielectric substrate 2 to form a metallized through hole array 4, and the metallized through holes are all connected to the top metal layer 1 and the bottom metal layer 3. The first resonant cavity 7, the second resonant cavity 8 and the third resonant cavity 9 distributed in the form of CT topology are formed through the metallized through hole array 4. The three resonant cavities are three intersecting circular cavities or polygonal cavities, and the three resonant cavities have the same shape and are centrally symmetrical. Part of the cavity wall is shared between two adjacent resonant cavities. The embodiment of the present invention uses three circular resonant cavities here, and the center connecting lines of the three resonant cavities form an equilateral triangle. A perturbation metallized through hole 10 is respectively arranged at the center of the first resonant cavity 7, the second resonant cavity 8 and the third resonant cavity 9. The three resonant cavities are mutually coupled through an inductive coupling window 15, and the inductive coupling window 15 is composed of a metallized through hole. The perturbation metallized through hole 10 and the metallized through hole of the inductive coupling window 15 penetrate the dielectric substrate 2 and are connected to the top metal layer 1 and the bottom metal layer 3.

[0029] In a possible implementation, the inductive coupling window 15 is composed of a cylindrical, cubic or rectangular metallized through hole. The perturbation metallized through hole 10 can also be a cylindrical, cubic or rectangular metallized through hole.

[0030] like Figure 2As shown, the top metal layer 1 is provided with three annular grooves 11 at positions corresponding to the centers of the three resonant cavities. The annular grooves 11 may be circular or polygonal. The embodiment adopts a circular shape. The three annular grooves 11 are respectively located in the middle of the first resonant cavity 7, the second resonant cavity 8 and the third resonant cavity 9. The perturbation metal through hole 10 on each resonant cavity is concentric with the annular groove 11. An adjustable varactor group 5 is provided on the top metal layer 1. One end of the adjustable varactor group 5 is connected to the top metal layer 1 inside the annular groove 1 and connected to the bottom metal layer 3 through the perturbation metallized through hole 10. The other end of the adjustable varactor group 5 is connected to the top metal layer 1 outside the annular groove 11. In a possible implementation manner, the adjustable varactor group 5 is composed of a plurality of varactors of the same model and specification. The model of the varactors in the embodiment is SMV1405.

[0031] like Figure 3 As shown, input and output feeding ports 12 are arranged on the bottom metal layer 3, and three annular graphene layers 6 are arranged at positions of the bottom metal layer 3 corresponding to the three annular grooves 11. Two input and output feeding ports 12 are arranged along a straight line, and the input and output feeding ports 12 include a grounded coplanar waveguide 13 and a connected arc-shaped slot line 14. The arc-shaped slot lines 14 of the two input and output feeding ports 12 surround the outside of the annular graphene layers 6 of the two resonant cavities. The grounded coplanar waveguide 13 leads the arc-shaped slot line 14 to the edges of both sides of the bottom metal layer 3. The dielectric substrate 2 is opened at the position of the resonant cavity corresponding to the grounded coplanar waveguide 13, and metallized through holes are arranged on both sides of the grounded coplanar waveguide 13 to connect with the metallized through hole array 4.

[0032] In a possible implementation, the input and output feed ports 12 are led out from the midpoints of the side walls of the two resonant cavities, and the structures of the two input and output feed ports 12 are mirror-symmetrical. The characteristic impedance of the grounded coplanar waveguide 13 is 50 ohms, the shape of the arc slot line 14 is an arc with an angle of θ, 0°≤θ≤180°, and the arc slot line 14 is composed of continuous curves or straight lines. The annular graphene layer 6 is circular or polygonal, and the shape of the annular graphene layer 6 is the same as the annular groove 11. The annular graphene layer 6 is arranged in the bottom metal layer 3, and the thickness is the same as the thickness of the bottom metal layer 3.

[0033] The frequency and amplitude independently adjustable SIW filter based on the CT topology of the present invention changes the capacitance value of the adjustable varactor group 5, keeps the sheet resistance of the annular graphene layer 6 unchanged, controls the center frequency of the filter to move, and the transmission amplitude at the same center frequency remains unchanged; keeps the capacitance value of the adjustable varactor group 5 unchanged, keeps the sheet resistance of the annular graphene layer 6 unchanged, and controls the center frequency of the filter to remain unchanged, and the transmission amplitude at the center frequency changes.

[0034] See also Figure 2 as well as Figure 3 The dielectric substrate 2 of the embodiment of the present invention adopts a F4bME substrate with a thickness of 5 mm and a relative dielectric constant ε r =3.55, loss tangent tanδ=0.0002, thickness is 5mm.

[0035] The diameter of the metallized through hole of the metallized through hole array 4 is 1 mm, the diameter of the metallized through hole constituting the inductive coupling window 15 is 0.8 mm, and the diameter of the perturbation metallized through hole 10 is 0.5 mm. Figure 2 and Figure 3 The geometric parameters are: R = 13, d1 = 5, d2 = 5.8, d3 = 7, d4 = 8.5, l1 = 7.5, l2 = l3 = 12.2, l4 = 16, R cpw =4.5, l CPW =8.8,w cpw =0.3,θ=90.5°.

[0036] Combination Figures 4 to 6 It can be seen that the frequency and amplitude independently adjustable SIW filter based on CT topology of the present invention adopts the method of loading adjustable varactor group 5 on the top metal layer 1 of the SIW filter to adjust the center frequency of the filter, and loading annular graphene layer 6 in the annular groove of the bottom metal layer 3 of the SIW filter to control the transmission amplitude of the filter, and the resonant cavity adopts CT topology to introduce a transmission zero point at the high end of the passband of the filter, thereby improving the out-of-band suppression characteristics. The SIW filter of the present invention regulates the center frequency by only changing the capacitance value C of the adjustable varactor group 5. v1 It can be achieved that the regulation of the transmission amplitude only changes the sheet resistance R of the annular graphene layer 6 g It can be realized, and the control method is simple and easy to operate.

[0037] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A frequency and amplitude independently adjustable SIW filter based on CT topology, characterized by: The invention comprises a top metal layer (1), a dielectric substrate (2) and a bottom metal layer (3) which are arranged in sequence from top to bottom; a plurality of metallized through holes are vertically penetrated through the dielectric substrate (2) to form a metallized through hole array (4); the metallized through holes are connected to the top metal layer (1) and the bottom metal layer (3); three resonant cavities distributed in a CT topology are formed through the metallized through hole array (4); a perturbation metallized through hole (10) is respectively arranged at the center of the three resonant cavities; the three resonant cavities are mutually coupled through an inductive coupling window (15); the inductive coupling window (15) is composed of a metallized through hole; the perturbation metallized through hole (10) and the metallized through hole of the inductive coupling window (15) penetrate the dielectric substrate (2) and are connected to the top metal layer (1) and the bottom metal layer (3); the top metal layer (1) is provided with three annular grooves (11) at positions corresponding to the centers of the three resonant cavities; the top metal layer ( 1) is provided with an adjustable varactor group (5), one end of the adjustable varactor group (5) is connected to the top metal layer (1) inside the annular groove (11) and is connected to the bottom metal layer (3) through a perturbation metallization through hole (10), and the other end is connected to the top metal layer (1) outside the annular groove (11); the bottom metal layer (3) is provided with an input and output feeding port (12), and the bottom metal layer (3) is provided with three annular graphene layers (6) at positions corresponding to the three annular grooves (11); the capacitance value of the adjustable varactor group (5) is changed, the sheet resistance of the annular graphene layer (6) remains unchanged, and the center frequency of the filter is controlled to move, so that the transmission amplitude at the same center frequency remains unchanged; the capacitance value of the adjustable varactor group (5) remains unchanged, the sheet resistance of the annular graphene layer (6) remains changed, and the center frequency of the filter is controlled to remain unchanged, so that the transmission amplitude at the center frequency changes.

2. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 1, characterized in that: The three resonant cavities distributed in the form of CT topology are three intersecting circular cavities or polygonal cavities. The three resonant cavities have the same shape and are centrally symmetrical, and two adjacent resonant cavities share part of the cavity wall.

3. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 2, characterized in that: Two input and output feeding ports (12) are arranged along a straight line. The input and output feeding ports (12) include a grounded coplanar waveguide (13) and a connected arc-shaped slot line (14). The arc-shaped slot lines (14) of the two input and output feeding ports (12) are surrounded by the outside of the annular graphene layer (6) of the two resonant cavities. The grounded coplanar waveguide (13) leads the arc-shaped slot line (14) to the edges of both sides of the bottom metal layer (3). The dielectric substrate (2) is opened at a position corresponding to the resonant cavity passing through the grounded coplanar waveguide (13), and metallized through holes are arranged on both sides of the grounded coplanar waveguide (13) to connect with the metallized through hole array (4).

4. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 3, characterized in that: The input and output feeding ports (12) are led out from the midpoints of the side walls of the two resonant cavities, and the structures of the two input and output feeding ports (12) are mirror-symmetrical; the arc-shaped slot line (14) is composed of continuous curves or straight lines spliced ​​together.

5. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 1, characterized in that: The inductive coupling window (15) is composed of a cylindrical, cube or rectangular metallized through hole.

6. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 1, characterized in that: The perturbation metallized through hole (10) is a cylindrical, cubic or rectangular metallized through hole.

7. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 1, characterized in that: The annular groove (11) is circular or polygonal, and the adjustable varactor group (5) is composed of a plurality of identical varactor tubes.

8. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 7, characterized in that: The annular graphene layer (6) is circular or polygonal, and the shape of the annular graphene layer (6) is the same as that of the annular groove (11).

9. The frequency and amplitude independently controllable SIW filter based on CT topology according to claim 1, characterized in that: The annular graphene layer (6) is arranged in the bottom metal layer (3), and has the same thickness as the bottom metal layer (3).

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