Cavity-based dual-band filtering balun

Patent metadata

Field	Value
Publication number	US-11380973-B2
Application number	US-201816627764-A
Country	US
Kind code	B2
Filing date	Oct 30, 2018
Priority date	Jun 27, 2018
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

The invention discloses a cavity-based dual-band filtering balun, which includes a first cavity resonator and a second cavity resonator which are connected by a metal plate, the first cavity resonator is provided with an input PCB board, a metal ground layer of the input PCB board is provided with an input through line, the other side of the input PCB board is provided with an input microstrip line, and the first cavity resonator is provided with an input slot corresponding to a position of the input through line; and two opposite outside surfaces of the second cavity resonator which are adjacent to the metal plate are each provided with an output PCB board, metal ground layers of the two output PCB boards are respectively provided with an output through line, the other sides of the two output PCB boards are each provided with an output microstrip line, and the second cavity resonator is provided with an output slot corresponding to a position of the output through line and communicated with the output through line. A main body of the dual-band filtering balun includes two cavity resonators, its structure is high in quality factor and low in insertion loss, and meanwhile, the requirement of two passbands is realized by using two fundamental modes of the cavity resonators, thus reducing a size of a circuit.

First claim

What is claimed is:

1. A cavity-based dual-band filtering balun, wherein the filtering balun comprises a cavity resonator, the cavity resonator is divided into a first cavity resonator and a second cavity resonator by an intermediate metal plate, edges of the intermediate metal plate are connected to inner walls of the cavity resonator, an outside wall of the first cavity resonator that faces the intermediate metal plate is provided with an input PCB board, and a metal ground layer of the input PCB board is in contact with the first cavity resonator; the metal ground layer on one side of the input PCB board is provided with an input through line, the other side of the input PCB board which is a top layer is provided with an input microstrip line, and one side of the first cavity resonator which is in contact with the input PCB board is provided with an input slot corresponding to a position of the input through line and communicated with the input through line; two opposite outside surfaces of the second cavity resonator that are adjacent to the intermediate metal plate are each provided with an output PCB board, and metal ground layers of the two output PCB boards are close to side surfaces of the second cavity resonator; the metal ground layers of the two output PCB boards are respectively provided with an output through line, the other sides of the two output PCB boards which are top layers are each provided with an output microstrip line, and two sides of the second cavity resonator that are close to the output PCB boards are respectively provided with an output slot corresponding to a position of the output through line and communicated with the output through line.

2. The cavity-based dual-band filtering balun according to claim 1 , wherein the intermediate metal plate comprises a metal partition plate and a rectangular slit opened in the metal partition plate, and the rectangular slit is parallel to the input through line and the input slot; the two output through lines are provided, which are respectively a first output through line and a second output through line, two output slots are provided, which are respectively a first output slot and a second output slot, the first output through line is parallel to the first output slot, the second output through line is parallel to the second output slot, and the first output through line and the first output slot are parallel to the second output through line and second output slot; two output microstrip lines are provided, which are respectively a first output microstrip line and a second output microstrip line, and the first output microstrip line is in central symmetry with the second output microstrip line; and two output PCB boards are provided, which are respectively a first output PCB board and a second output PCB board.

3. The cavity-based dual-band filtering balun according to claim 2 , wherein an input dielectric substrate of the input PCB board has a dielectric constant of 2.55.

4. The cavity-based dual-band filtering balun according to claim 2 , wherein the first output PCB board comprises a first output dielectric substrate, a first output metal ground layer and the first output microstrip line, and the first output through line is arranged on the first output metal ground layer; and the second output PCB board comprises a second output dielectric substrate, a second output metal ground layer and the second output microstrip line, and the second output through line is arranged on the second output metal ground layer.

5. The cavity-based dual-band filtering balun according to claim 4 , wherein both the first output dielectric substrate and the second output dielectric substrate have a dielectric constant of 2.55.

6. The cavity-based dual-band filtering balun according to claim 2 , wherein the input through line is inclined at an included angle θ 1 to a horizontal direction; and the first output through line and the second output through line are both inclined at an included angle θ 2 to the horizontal direction, the first output through line deviates upwardly from a center position of the first output PCB board, the second output through line deviates downwardly from a center position of the second output PCB board, and the first output through line and the second output through line deviate by a same distance.

7. The cavity-based dual-band filtering balun according to claim 2 , wherein the input microstrip line is located at a middle position of the input PCB board, one end of the input microstrip line is flush with a bottom end edge of the input PCB board, and the other end of the input microstrip line extends upwardly along a vertical direction to be staggered with the input through line and passes over the input through line; one end of the first output microstrip line is flush with a bottom end edge of the first output PCB board, and the other end of the first output microstrip line extends upwardly along the vertical direction to be staggered with the first output through line and passes over the first output through line; and one end of the second output microstrip line is flush with a top end edge of the second output PCB board, the other end of the second output microstrip line extends downwardly along the vertical direction to be staggered with the second output through line and passes over the second output through line, and the first output microstrip line is in central symmetry with the second output microstrip line.

8. The cavity-based dual-band filtering balun according to claim 2 , wherein the rectangular slit of the intermediate metal plate is inclined at an included angle θ 1 to a horizontal direction, and the input through line is parallel to the rectangular slit.

9. The cavity-based dual-band filtering balun according to claim 1 , wherein a characteristic impedance of the input microstrip line and a characteristic impedance of the output microstrip line are both 50Ω.

10. The cavity-based dual-band filtering balun according to claim 1 , wherein the first cavity resonator, the second cavity resonator and the intermediate metal plate are made of a silver-plated aluminum substrate.

Assignees

• Univ South China Tech

Inventors

• Li Yuanchun
• Fang Xin

Classifications

• H01P1/208 Primary

  Cascaded cavities; Cascaded resonators inside a hollow waveguide structure (H01P1/205 takes precedence) · CPC title

• H01P5/1007 Primary

  Microstrip transitions to Slotline or finline · CPC title

• H01P5/107 Primary

  Hollow-waveguide/strip-line transitions · CPC title