Multi-pole split ring resonator bandpass filter

• US 5,164,690 A
• Filed: 06/24/1991
• Issued: 11/17/1992
• Est. Priority Date: 06/24/1991
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Avanic, Branko, Ooi, Leng H., Yeh, Peter J.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/719,449
• Time in Patent Office: 512 Days
• Field of Search: 333/202, 333/204, 333/205, 333/219, 333/235, 333/246, 455/326, 455/327
• US Class Current: 333/204
• CPC Class Codes: H01P 1/20381 Special shape resonators

Abstract

A multipole bandpass filter (40) comprises a first microstrip split-ring resonator (12), having at least a first edge and a second edge, the first edge having a gap (20) therein, and an input. The bandpass filter (40) also comprises a second microstrip split-ring resonator (14), having at least a first edge and a second edge, the second edge of the second microstrip split-ring resonator comprising a gap (26) therein and a balanced output (30, 32). The bandpass filter also includes at least one straight line quasi-combline resonator (22), disposed between the first microstrip split-ring resonator, and the second microstrip split-ring resonator.

Claims

1. A multi-pole bandpass filter, comprising:

a first port;

a first microstrip split-ring resonator, having at least a first edge and a second edge, the first edge having a gap therein, and the first edge being coupled to the first port;

a second microstrip split-ring resonator, having at least a first edge and a second edge, and the second edge of the second microstrip split-ring resonator comprising a gap therein;

a second port coupled to the second edge of the second microstrip split-ring resonator, the second port comprising a first terminal located at one side of the gap in the second edge of the second microstrip split-ring resonator, and a second terminal symmetrically located at the other side of the gap in the second edge of the second microstrip split-ring resonator; and

at least one straight line quasi-combine resonator, disposed between the first microstrip split-ring resonator, and the second microstrip split-ring resonator.

2. The bandpass filter of claim 1, further comprising a first capacitor coupled across the gap in the first microstrip split-ring resonator.

3. The bandpass filter of claim 1, further comprising a second capacitor coupled across the gap in the second microstrip split-ring resonator.

4. The bandpass filter of claim 1, wherein the first port comprises a first terminal located at one side of the gap in the first edge of the first microstrip split-ring resonator.

5. The bandpass filter of claim 4, wherein the first port comprises a second terminal symmetrically located at the other side of the gap in the first edge of the first microstrip split-ring resonator.

6. The bandpass filter of claim 1, wherein the at least one straight line quasi-combline resonator comprises:

first and second ends;

a first capacitor disposed between the first end of the at least one straight line quasi-combline resonator, and ground potential; and

a second capacitor disposed between the second end of the at least one straight line quasi-combline resonator, and ground potential.

7. The bandpass filter of claim 1, wherein:

the first microstrip split-ring resonator comprises a feed terminal for coupling to a direct current voltage at a virtual ground point in the first microstrip split-ring resonator; and

the second microstrip split-ring resonator comprises a feed terminal for couping to a direct current voltage at a virtual ground point in the second microstrip split-ring resonator.

8. A communication device comprising:

receiver means for receiving radio-frequency signals;

a bandpass filter, coupled to the receiver means, comprising;

a first port;

a first microstrip split-ring resonator, having at least a first edge and a second edge, the first edge having a gap therein, and the first edge being coupled to the first port;

a second microstrip split-ring resonator, having at least a first edge and a second edge, and the second edge of the second microstrip split-ring resonator comprising a gap therein;

a second port coupled to the second edge of the second microstrip split-ring resonator, the second port comprising a first terminal located at one side of the gap in the second edge of the second microstrip split-ring resonator, and a second terminal symmetrically located at the other side of the gap in the second edge of the second microstrip split-ring resonator for providing a balanced output for the bandpass filter; and

at least one straight line quasi-combline resonator, disposed between the first microstrip split-ring resonator, and the second microstrip split-ring resonator.

9. The communication device of claim 8, wherein the bandpass filter further comprises a first capacitor coupled across the gap in the first microstrip split-ring resonator.

10. The communication device of claim 8, wherein the bandpass filter further comprises a second capacitor coupled across the gap in the second microstrip split-resonator.

11. The communication device of claim 8, wherein the first port comprises a first terminal located at one side of the gap in the first edge of the first microstrip split-ring resonator.

12. The communication device of claim 11, wherein the first port comprises a second terminal symmetrically located at the other side of the gap in the first edge of the first microstrip split-ring resonator.

13. The communication device of claim 8, further comprising a frequency mixer having a balanced input coupled to the balanced output of the bandpass filter.

14. The communication device of claim 8, wherein the at least one straight line quasi-combline resonator comprises:

first and second ends;

a first capacitor disposed between the first end of the at least one straight line quasi-combline resonator, and ground potential; and

a second capacitor disposed between the second end of the at least one straight line quasi-combline resonator, and ground potential.

15. The communication device of claim 8, wherein:

the first microstrip split-ring resonator comprises a feed terminal for coupling to a direct current voltage at a virtual ground point in the first microstrip split-ring resonator; and

the second microstrip split-ring resonator comprises a feed terminal for coupling to a direct current voltage at a virtual ground point in the second microstrip split-ring resonator.