Dielectric filter using the TEM mode

• US 5,929,725 A
• Filed: 01/08/1997
• Issued: 07/27/1999
• Est. Priority Date: 01/08/1996
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Matsumoto, Haruo, Toda, Jun, Tsunoda, Kikuo
• Primary Examiner(s): Ham, Seungsook
• Application Number:
  US08/780,320
• Time in Patent Office: 930 Days
• Field of Search: 333/202, 333/203, 333/204, 333/206
• US Class Current: 333/202
• CPC Class Codes: H01P 1/16 for mode selection, e.g. mode suppression or mode promotion; for mode conversion
• CPC Class Codes: H01P 1/2056 Comb filters or interdigital filters with metallised resonator holes in a dielectric block

Abstract

A dielectric filter with a shorting conductor for improving a spurious response characteristic in a mode other than a fundamental mode (TEM mode). Two resonator holes having inner conductors formed on their inner surfaces are formed through a dielectric block between a pair of end surfaces. An outer conductor is formed on outer surfaces of the dielectric block. A through hole is formed through a central portion of the dielectric block between two major surfaces of the block, and a shorting conductor is formed on the inner surface of the through hole to be connected to outer conductor portions on the two major surfaces of the dielectric block. The shorting conductor is disposed at a location where the electric field strength of the undesired mode is high.

Claims

1. A dielectric filter for using the TEM mode comprising:

a dielectric block having a pair of end surfaces;

a plurality of resonators comprising respective inner conductors extending between the pair of end surfaces of said dielectric block;

an outer conductor formed on outer surfaces of said dielectric block;

non-conductive sections adjacent to respective ones of said plurality of inner conductors and defining respective ends of said ones of said plurality of inner conductors; and

a shorting conductor disposed in a portion of said dielectric block which is located between a corresponding pair of said resonators and at which the strength of an electric field in a mode other than the TEM mode is high when said corresponding pair of resonators are excited,

wherein said shorting conductor shorts portions of said outer conductor formed on two major surfaces of said dielectric block, said two major surfaces extending parallel to the direction of arrangement of said plurality of inner conductors and also parallel to the lengthwise direction of said plurality of inner conductors, and

wherein said shorting conductor is provided by an inner conductor in a throughhole extending between said two major surfaces;

wherein said shorting conductor is disposed only at a position located at 1/2 of a dimension of said dielectric block along the direction of arrangement of said inner conductors, and at 1/2 of another dimension of said dielectric block along the lengthwise direction of said inner conductors, so as to suppress spurious response in the TE101 mode.

3. A dielectric filter according to claim 1, wherein said inner conductors and non-conductive sections are disposed on inner cylindrical surfaces of resonator holes which extend between the pair of end surfaces of said dielectric block.

4. A dielectric filter according to claim 3, further comprising a pair of input/output electrodes disposed on said dielectric block so as to be capacitively coupled with corresponding ones of said plurality of resonators, said outer conductor being formed on the entire outer surface of said dielectric block except for portions surrounding said input/output electrodes.

5. A dielectric filter according to claim 1, further comprising a pair of input/output electrodes disposed on said dielectric block so as to be capacitively coupled with corresponding ones of said plurality of resonators, said outer conductor being formed on the entire outer surface of said dielectric block except for portions surrounding said input/output electrodes.

2. A dielectric filter for using the TEM mode comprising:

a dielectric block having a pair of end surfaces;

a plurality of resonators comprising respective inner conductors extending between the pair of end surfaces of said dielectric block;

an outer conductor formed on outer surfaces of said dielectric block;

non-conductive sections adjacent to respective ones of said plurality of inner conductors and defining respective ends of said ones of said plurality of inner conductors; and

a shorting conductor disposed in a portion of said dielectric block which is located between a corresponding pair of said resonators and at which the strength of an electric field in a mode other than the TEM mode is high when said corresponding pair of resonators are excited,

wherein said shorting conductor shorts portions of said outer conductor formed on two major surfaces of said dielectric block, said two major surfaces extending parallel to the direction of arrangement of said plurality of inner conductors and also parallel to the lengthwise direction of said plurality of inner conductors, and

wherein said shorting conductor is provided by an inner conductor in a throughhole extending between said two major surfaces;

wherein said shorting conductor is disposed only at a position located at 1/4 of a dimension of said dielectric block along the direction of arrangement of said inner conductors, and at 1/2 of another dimension of said dielectric block along the lengthwise direction of said inner conductors, so as to suppress spurious response in the TE102 mode.

6. A dielectric filter according to claim 2, further comprising a pair of input/output electrodes disposed on said dielectric block so as to be capacitively coupled with corresponding ones of said plurality of resonators, said outer conductor being formed on the entire outer surface of said dielectric block except for portions surrounding said input/output electrodes.

7. A dielectric filter for using the TEM mode comprising:

a dielectric block having a pair of end surfaces, and side surfaces extending between said end surfaces;

three resonators comprising respective inner conductors extending between the pair of end surfaces of said dielectric block, and disposed so as to define a direction of arrangement between two opposed side surfaces of said dielectric block;

an outer conductor formed on outer surfaces of said dielectric block;

non-conductive sections adjacent to respective ones of said plurality of inner conductors and defining respective ends of said ones of said plurality of inner conductors; and

a pair of shorting conductors, each disposed respectively in a portion of said dielectric block which is located between a corresponding pair of said resonators and at which the strength of an electric field in a mode other than the TEM mode is high when said corresponding pair of resonators are excited,

wherein said shorting conductors short portions of said outer conductor formed on two major surfaces of said dielectric block, said two major surfaces extending parallel to the direction of arrangement of said plurality of inner conductors and also parallel to the lengthwise direction of said plurality of inner conductors,

wherein said shorting conductors are provided by respective inner conductors in corresponding throughholes extending between said two major surfaces, and

wherein each said shorting conductor is disposed only at a position located at 1/4 of a dimension of said dielectric block along the direction of arrangement of said inner conductors, from a corresponding one of said two opposed side surfaces, and at 1/2 of another dimension of said dielectric block along the lengthwise direction of said inner conductors, so as to suppress spurious response in the TE102 mode.

8. A dielectric filter according to claim 7, wherein said inner conductors and non-conductive sections are disposed on inner cylindrical surfaces of resonator holes which extend between the pair of end surfaces of said dielectric block.

9. A dielectric filter according to claim 8, further comprising a pair of input/output electrodes disposed on said dielectric block so as to be capacitively coupled with corresponding ones of said plurality of resonators, said outer conductor being formed on the entire outer surface of said dielectric block except for portions surrounding said input/output electrodes.

10. A dielectric filter according to claim 7, further comprising a pair of input/output electrodes disposed on said dielectric block so as to be capacitively coupled with corresponding ones of said plurality of resonators, said outer conductor being formed on the entire outer surface of said dielectric block except for portions surrounding said input/output electrodes.