MICROWAVE RESONATOR

• US 20020003461A1
• Filed: 07/19/1999
• Published: 01/10/2002
• Est. Priority Date: 12/06/1996
• Status: Active Grant

• Current Assignee: Filtronic Plc
• Original Assignee: Filtronic Plc
• Inventors: HUNTER, IAN CHARLES
• Granted Patent: US 6,359,534 B2
• Time in Patent Office: Days
• US Class Current: 333/219.1
• CPC Class Codes: H01P 1/2084 with dielectric resonators
• CPC Class Codes: H01P 7/105 Multimode resonators

Abstract

A microwave resonator, particularly for use in cellular telecommunications, comprising a hollow electrical conductor defining a resonant cavity and a substantially cubic member located within the cavity. The substantially cubic member has a high dielectric constant compared with the remainder of the cavity.

Claims

1. A microwave frequency resonator, the resonator comprising a hollow electrical conductor defining a resonant cavity, and a substantially cubic member located within the cavity and having a high dielectric constant compared with the remainder of the cavity.

2. A resonator according to claim 1, wherein the substantially cubic member is constructed from ceramic material and the remainder of the cavity contains air.

3. A resonator according to claim 2, wherein the ceramic material is ZTS.

4. A resonator according to any one of the preceding claims, further comprising coupling means for coupling together resonant modes of the resonator corresponding to microwaves propagating across the cavity in mutually orthogonal directions.

5. A resonator according to claim 4, wherein the coupling means comprises at least one electrically conducting loop having ends connected to the hollow electrical conductor, wherein the or each loop lies in a respective plane oriented at substantially 45°

to an end face of the substantially cubic member.

6. A resonator according to any one of the preceding claims, further comprising signal input means for inputting electrical signals into the resonator.

7. A resonator according to claim 6, wherein the connecting means comprises a loop of electrical conductor connected at one end thereof to the hollow electrical conductor and adapted to be connected at the other end thereof to a coaxial cable.

8. A resonator according to any one of the preceding claims, further comprising tuning means for tuning the or each resonant frequency of the resonator.

9. A resonator according to claim 8, wherein the tuning means comprises at least one tuning member material having a dielectric constant high compared with said remainder of the cavity and adjustment means for adjusting the spacing between the tuning member and the substantially cubic member.

10. A resonator according to claim 9, wherein the tuning member comprises a disk of the same material as the substantially cubic member and connected to the hollow electrical conductor by means of an electrical insulator.

11. A resonator according to any one of the preceding claims, wherein the cavity is substantially cubic and the substantially cubic member is arranged in the cavity with faces thereof extending substantially parallel to the adjacent faces of the hollow electrical conductor.

12. A resonator according to any one of the preceding claims, further comprising support means for supporting the substantially cubic member in the cavity.

13. A resonator according to claim 12, wherein the support means comprises a first dielectric member arranged between a face of the substantially cubic member and the adjacent face of the hollow electrical conductor.

14. A resonator according to claim 13, wherein the support means further comprises a second support member arranged between a face of the substantially cubic member and the adjacent face of the hollow electrical conductor and on an opposite side of the substantially cubic member to the first support member.

15. A resonator according to claim 14, wherein the support means further comprises urging means for placing the substantially cubic member under compression between the first and second support members.

16. A resonator according to any one of claims 13 to 15, wherein the first and/or second support members are formed substantially from alumina.

18. A microwave frequency bandpass filter, the filter comprising signal input means for inputting electrical signals into the filter, signal output means for outputting electrical signals from the filter, and at least one resonator according to any one of the preceding claims connected between the signal input means and the signal output means.

19. A filter according to claim 18, comprising a plurality of said resonators electrically coupled together.

20. A microwave frequency bandstop filter, the filter comprising a 3 dB hybrid, and a bandpass filter according to claim 18 or 19 connected between a first pair of terminals of the hybrid such that the transmission response between a second pair of terminals of the hybrid represents the reflection coefficient of the bandpass filter.

21. A filter according to claim 20, wherein an even mode impedance of the bandpass filter is connected to one terminal of said first pair and an odd mode impedance of the bandpass filter is connected to the other terminal of said first pair.

22. A filter according to claim 20 or 21, wherein the hybrid comprises a microstrip coupler.

23. A microwave frequency power combiner, the combiner comprising amplifier means for inputting a plurality of electrical signals at different frequencies into at least one resonator according to any one of claims 1 to 17, and output means for outputting electrical signals from the or each resonator to a microwave frequency antenna.

17. A microwave frequency resonator, the resonator substantially as hereinbefore described with reference to the accompanying drawings.