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CN-121983767-A - Miniaturized filter with square SIW cavity and strip line resonator mixed

CN121983767ACN 121983767 ACN121983767 ACN 121983767ACN-121983767-A

Abstract

The invention discloses a miniaturized filter with a square SIW cavity and a strip line resonator, which comprises a dielectric layer, a top metal layer, a middle metal layer, a bottom metal layer, a metallized through hole array, a first metallized blind hole and a second metallized blind hole, a feed microstrip line and a strip line resonator, wherein the top metal layer is positioned on the upper surface of the dielectric layer, the middle metal layer is positioned in the middle of the dielectric layer, the bottom metal layer is positioned on the lower surface of the dielectric layer, the metallized through hole array penetrates through the dielectric layer and is connected with the top metal layer and the bottom metal layer, the first metallized blind hole and the second metallized blind hole are used for connecting the middle metal layer and the bottom metal layer, the first metallized through hole and the second metallized through hole are connected with the top metal layer and the bottom metal layer, and the feed microstrip line is embedded in the SIW cavity.

Inventors

  • XIE WENQING
  • ZHU FANG

Assignees

  • 杭州电子科技大学

Dates

Publication Date
20260505
Application Date
20260210

Claims (10)

  1. 1. A miniaturized filter with a square SIW cavity and a strip line resonator mixed is characterized by comprising a dielectric layer (1); The top metal layer (2) is positioned on the upper surface of the dielectric layer (1); An intermediate metal layer located in the middle of the dielectric layer (1); The bottom metal layer (3) is positioned on the lower surface of the dielectric layer (1); A metallized through hole array (4) penetrating the dielectric layer (1) and connecting the top metal layer (2) and the bottom metal layer (3); the first metalized blind holes (5) and the second metalized blind holes (6) are used for connecting the middle metal layer and the bottom metal layer (3); the first metallized through hole (9) and the second metallized through hole (10) are connected with the top metal layer (2) and the bottom metal layer (3); a feed microstrip line (11); The method comprises the steps of constructing a square SIW cavity by a metallized through hole array (4), a top metal layer (2) and a bottom metal layer (3), wherein the middle metal layer comprises a full-wavelength strip line (7) and a quarter-wavelength strip line (8), the electrical lengths of the full-wavelength strip line (7) and the quarter-wavelength strip line (8) are respectively full-wavelength and quarter-wavelength, the physical lengths LP1 and LP2 of the full-wavelength strip line (7) and the quarter-wavelength strip line (8) respectively meet the conditions that the resonance frequency of a corresponding mode is near the center frequency of a filter, two ends of the full-wavelength strip line (7) are provided with first metallized blind holes (5) to form a full-wavelength strip line resonator with a terminal short circuit, one end of the quarter-wavelength strip line (8) is provided with a second metallized blind hole (6) to form a quarter-wavelength strip line resonator with a terminal short circuit, and the other end of the quarter-wavelength strip line resonator is open-circuited, and the secondary modes of the full-wavelength strip line resonator, the full-wavelength strip line resonator and the primary modes of the quarter-wavelength strip line resonator and the TE modes of the square SIW cavity are near the center frequency and the TE mode are all transmitted at the center frequencies of the center frequency of the TE mode of the filter 201; The outer side ends of the metallized through hole arrays (4) of the square SIW cavity are provided with a feed window, and the feed window of the top metal layer (2) is connected with a feed microstrip line (11) as an input/output feed port.
  2. 2. The miniaturized filter mixed by the square SIW cavity and the strip line resonator according to claim 1 is characterized in that the feed microstrip line (11) is orthogonally placed, and L-shaped feed slots (12) are formed on two sides of the feed microstrip line (11) and the top metal layer (2).
  3. 3. The miniaturized filter mixed with a strip line resonator with square SIW cavity according to claim 2, characterized in that the characteristic impedance of the feed microstrip line (11) is 50 ohms.
  4. 4. A miniaturized filter in which square SIW cavities are mixed with stripline resonators as claimed in claim 3, characterized in that the first metallized blind holes (5) on both sides of the full-wave stripline (7) are the same diameter.
  5. 5. The miniaturized filter mixed with a strip line resonator of square SIW cavity according to claim 1, wherein the magnitude of the internal coupling amount is controlled by adjusting the line widths WP1 and WP2 of the full wavelength strip line (7), the quarter wavelength strip line (8), the diameters Dv1 and Dv2 of the first metallized blind hole (5) and the second metallized blind hole (6), and the offsets DP1 and DP2 from the centerline of the SIW cavity.
  6. 6. The miniaturized filter mixed with the strip line resonator and the square SIW cavity according to claim 1, wherein the resonance frequencies of TE102 and TE201 of the square SIW cavity are separated by adjusting and controlling the offset DP3 of the first metalized through hole (9) and the second metalized through hole (10) which are positioned on the diagonal of T1 and T2 and the diagonal boundary of the square SIW cavity.
  7. 7. The miniaturized filter of claim 1 wherein the second order mode of the stripline resonator is a full-wavelength stripline resonator, the fundamental mode of the quarter-wavelength stripline resonator, and TE102 and TE201 of the square SIW cavity are used to construct the transmission pole of the filter, while the additional transmission zero is introduced as NRN through the fundamental mode TE101 of the SIW cavity, and the physical lengths LP1 and LP2 of the two striplines are adjusted so that the resonant frequency of the corresponding mode is near the center frequency of the filter.
  8. 8. The miniaturized filter of the combination of square SIW cavity and stripline resonator of claim 1, wherein the external quality factor is adjusted by controlling the lengths LS1 and LS2 of the L-shaped feed slot (12), the line width WS, and the horizontal offset Df of the feed microstrip line with respect to the center of the filter.
  9. 9. The miniaturized filter mixed with the strip line resonator and the square SIW cavity according to claim 1, wherein the dielectric layer (1) is a Tanconic TLY-5 dielectric substrate with a relative dielectric constant of 2.2, a loss tangent of 0.0009 and a thickness of 0.508 mm.
  10. 10. The miniaturized filter of claim 1 wherein the two higher order orthogonal modes TE 102 and TE 201 of the square SIW cavity form the transmission pole of the filter, the fundamental mode TE 101 of the square SIW cavity is used as the NRN structure, an additional transmission zero is introduced on the stop band of the filter, the secondary mode of the full-wavelength strip line is used as the resonator to form the transmission pole of the filter, the fundamental mode resonance frequency of the quarter-wavelength strip line is located near the center frequency to form the transmission pole of the filter, the two resonant modes TE 102 and TE 201 of the square SIW cavity are respectively resonator 1 and resonator 2, the fundamental mode of the quarter-wavelength strip line (8) is resonator 3, the secondary mode of the full-wavelength strip line (7) is resonator 4, the coupling coefficient between resonator 1 and resonator 3 is M 13 , the coupling coefficient between resonator 2 and resonator 4 is M 24 , and the output of the same-phase electric field is input to the filter when the orthogonal feed is used, and the output of the electric field is S1 ＝M L1 ,M S2 ＝-M L2 .

Description

Miniaturized filter with square SIW cavity and strip line resonator mixed Technical Field The invention belongs to the technical field of microwaves, relates to a high-selectivity Substrate Integrated Waveguide (SIW) filter, and particularly relates to a SIW high-selectivity single-cavity filter with a built-in strip line resonator. Background Substrate Integrated Waveguide (SIW) filters have the advantage of low loss characteristics of conventional metal waveguides and easy integration of planar circuits, and have been widely studied in microwave filter design. However, the conventional SIW has a large size, and it is difficult to meet the miniaturization requirement of the modern microwave circuit, and although structures such as half-mode SIW (HMSIW) and quarter-mode SIW (QMSIW) have been proposed to reduce the size of the filter, such structures are usually in a half-open form, and there are problems of large radiation loss, insufficient frequency selectivity, and the like. By combining the SIW cavity with other planar transmission line resonant structures, transmission zeroes can be additionally introduced while reducing the filter volume. For example, a half-open transmission line structure such as a coplanar waveguide (CPW) or a microstrip line is etched on the metal surface of the SIW cavity, and the structure can be used as an additional resonator in the filter except the SIW cavity through special design, but because the structure is half-open, the existence of the structure damages the integrity and the no-load quality factor (Q U) of the SIW cavity, so that the insertion loss is increased and the electromagnetic compatibility problem is introduced, and on the other hand, the insertion loss of the filter is further increased because the Q U of the planar transmission line resonator such as the CPW and the microstrip is far lower than the Q U of the SIW cavity. Therefore, there is a need for a filter structure capable of effectively introducing a plurality of transmission zeros and achieving miniaturization while maintaining the sealing and low loss characteristics of the SIW cavity. Disclosure of Invention Aiming at the problems of large size, poor selectivity and increased insertion loss caused by surface etching of a transmission line of the conventional SIW filter, the invention provides a method for embedding a strip line in a square SIW dual-mode cavity, wherein a secondary mode of a full-wavelength strip line resonator and a fundamental mode of a quarter-wavelength strip line resonator are combined with TE 201 and TE 102 modes of the square SIW dual-mode cavity, and four transmission zeros are introduced near a passband; the volume of the filter is greatly reduced and the selectivity of the filter is improved while the sealing performance of the whole structure of the filter is ensured. The invention adopts the following technical scheme: A miniaturized filter of square SIW cavities mixed with stripline resonators, comprising: A dielectric layer; The top metal layer is positioned on the upper surface of the dielectric layer; An intermediate metal layer located at a middle position of the dielectric layer; the bottom metal layer is positioned on the lower surface of the dielectric layer; the metallized through hole array penetrates through the dielectric layer and is connected with the top metal layer and the bottom metal layer; the first metallization blind hole and the second metallization blind hole are used for connecting the middle metal layer and the bottom metal layer; the first metallization through hole and the second metallization through hole are connected with the top metal layer and the bottom metal layer; a feed microstrip line; Wherein: The method comprises the steps of forming a square SIW cavity by a metallized through hole array, a top metal layer and a bottom metal layer, forming a full-wavelength strip line and a quarter-wavelength strip line by an intermediate metal layer, forming a full-wavelength strip line and a quarter-wavelength strip line by the electrical lengths of the full-wavelength strip line and the quarter-wavelength strip line respectively, enabling the resonant frequencies of corresponding modes to be near the central frequency of a filter by the physical lengths L P1 and L P2 of the full-wavelength strip line and the quarter-wavelength strip line respectively, forming a full-wavelength strip line resonator with a terminal short circuit by the two ends of the full-wavelength strip line through first metallized blind holes, forming a quarter-wavelength strip line resonator with one end short circuit and one end open circuit by the one end by the second metallized blind holes by the one end of the quarter-wavelength strip line, and forming four transmissions of the filter by the secondary mode of the full-wavelength strip line resonator, the fundamental mode of the quarter-wavelength strip line resonator and the TE 102 and the TE 201 modes in the SIW cavity,