Resonator and high-frequency filter

• US 6,933,811 B2
• Filed: 03/16/2004
• Issued: 08/23/2005
• Est. Priority Date: 06/15/2000
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Enokihara, Akira, Okajima, Michio
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): TAKAOKA, DEAN O
• Application Number:
  US10/801,905
• Publication Number:
  US 20040174234A1
• Time in Patent Office: 525 Days
• Field of Search: 333/202, 333/219, 333/219.1, 333/230, 333/234
• US Class Current: 333/202
• CPC Class Codes: H01P 1/2084 with dielectric resonators
• CPC Class Codes: H01P 7/10 Dielectric resonators

Abstract

The resonator of the present invention includes a cylindrical dielectric and a conductor film covering the surface of the dielectric in close contact therewith. The conductor film is constructed of a cylindrical portion and two flat portions, and is formed by subjecting the surface of the dielectric to metallization or the like. With the conductor film formed in close contact with the dielectric, deterioration of the Q value and the like caused by instability of connection at the corners can be suppressed even when a radio frequency induced current flows from the cylindrical portion over the two flat portions.

Claims

1. A resonator comprising:

a columnar shielding case composed of a conductive material and defining an interior space; and

a dielectric made of a dielectric ceramic material substantially filling the entire interior space, the resonator using a resonant mode causing generation of a current crossing a corner of the columnar shielding case;

wherein the resonator using a TM mode, wherein the dielectric includes a center portion and an outer portion covering at least part of the center portion, and the dielectric constant of the center portion is higher than the dielectric constant of the outer portion.

2. The resonator of claim 1, wherein the resonant mode is a TM mode.

3. The resonator of claim 1, wherein the columnar shielding case is in a shape of a cylinder or a square pole.

4. The resonator of claim 1, wherein the shielding case is a metallized layer formed on the surface of the dielectric.

5. A radio frequency filter having a columnar resonator using a resonant mode causing generation of a current crossing a corner, the resonator comprising:

a dielectric made of a dielectric ceramic material having top and bottom surfaces and at least one side surface; and

a shielding conductor surrounding the dielectric formed in direct contact with the top, bottom and side surface of the dielectric;

wherein the resonator using a TM mode, wherein the dielectric includes a center portion and an outer portion covering at least part of the center portion, and the dielectric constant of the center portion is higher than the dielectric constant of the outer portion.

6. A radio frequency filter having a resonator, the resonator comprising:

a dielectric having a hole;

a case surrounding the dielectric;

an elastic layer sandwiched between the lid and the case body;

a planar conductive foil sheet sandwiched between the elastic layer and the case body;

the dielectric having lower and upper ends that are respectively disposed in contact with an inner face of the case and the conductive foil sheet; and

a conductor rod inserted into the hole of the dielectric, the insertion depth of the conductor rod being variable,

wherein a resonant frequency is adjusted with the insertion depth of the conductor rod into the hole.

7. A radio frequency filter having a plurality of resonators at least including an input-stage resonator having a dielectric and receiving a radio frequency signal from an external device and an output-stage resonator having a dielectric and outputting a radio frequency signal to an external device, the radio frequency filter comprising:

a case surrounding the plurality of resonators for electromagnetically shielding the respective resonators;

wherein each of the input-stage resonator and the output-stage resonator comprise;

(a) a case body and a lid;

(b) a dielectric fixed therein;

(c) an elastic layer which is sandwiched between the lid and the case body; and

(d) a planar conductive foil sheet which is sandwiched between the elastic layer and the case body;

(e) wherein lower and upper ends of the dielectric are respectively fixed to an inner face of the bottom of the case body and the conductive foil in contact therewith,

a partition formed between resonators of which electromagnetic fields are coupled with each other among the plurality of resonators;

an input-stage coupling window formed at the partition; and

an input-stage coupling degree adjusting member made of a conductor rod for adjusting the area of the inter-stage coupling window.