Tuneable cavity resonator

• US 6,549,104 B1
• Filed: 06/08/2001
• Issued: 04/15/2003
• Est. Priority Date: 09/09/1998
• Status: Expired due to Fees

• Current Assignee: Tesat Spacecom GmbH & Company KG (Airbus SE), Forschungszentrum Jã¼Lich GmbH (Bundesrepublik Deutschland)
• Original Assignee: Forschungszentrum Jã¼Lich GmbH (Bundesrepublik Deutschland), Robert Bosch GmbH
• Inventors: Ghosh, Indra, Schieber, Klaus, Klein, Norbert, Poppe, Ulrich
• Primary Examiner(s): Ham, Seungsook
• Application Number:
  US09/786,760
• Time in Patent Office: 676 Days
• Field of Search: 333/202, 333/224-226, 333/231, 333/232, 333/233, 333/235, 333/219.1, 333/219, 331/107.DP
• US Class Current: 333/235
• CPC Class Codes: H01P 7/06 Cavity resonators

Abstract

The invention concerns a tunable cavity resonator that comprises a resonator body (2, 3, 4) defining a cavity (5), a tuning plate (28) whose position with respect to the resonator body (2, 3, 4) is modifiable and which influences the resonance frequency (ω_R) of the cavity resonator, and an adjustment device (22, 26) for mechanically changing the position of the tuning plate (28), which is characterized in that a conversion ratio mechanism (18, 20) couples the adjustment device (22, 26) to the tuning plate (28) in terms of movement and converts a linear excursion (Δx₁) generated by the adjustment device (22, 26), at a predefined ratio (U), into a reduced linear excursion (Δx₂) that acts on the tuning plate (28), the conversion ratio mechanism (18, 20) comprising a first spring element (20) whose end toward the adjustment device is deflectable with the linear excursion (Δx₁) generated by the adjustment device (22, 26), and a second spring element (18) which impinges with an opposing force on the end of the first spring element (20) remote from the adjustment device.

Claims

1. A tunable cavity resonator, comprising:

a resonator body (2, 3, 4) defining a cavity (5);

a tuning plate (28) whose position with respect to the resonator body (2, 3, 4) is adjustable and which influences the resonance frequency (ω

_R) of the cavity resonator; and

an adjustment device (22, 26) for mechanically changing the position of the tuning plate (28),

characterized by a conversion ratio mechanism (18, 20) which couples the adjustment device (22, 26) to the tuning plate (28) in terms of movement and which converts a linear excursion (Δ

x₁) generated by the adjustment device (22, 26), at a predefined ratio (U), into a reduced linear excursion (Δ

x₂) that acts on the tuning plate (28), the conversion ratio mechanism (18, 20) comprising a first spring element (20) whose end toward the adjustment device is deflectable with the linear excursion (Δ

x₁) generated by adjustment device (22, 26), and a second spring element (18) which impinges with an opposing force on the end of the first spring element (20) remote from the adjustment device.

2. The tunable cavity resonator as defined in claim 1, characterized in that the first spring element is formed from at least one cup spring (20);

and that the second spring element is implemented by a plate spring (18) that is immobilized at the periphery and impinged upon centrally by the cup spring (20).

3. The tunable cavity resonator as defined in claim 2, characterized in that

the resonator body comprises a cylindrical peripheral wall (3), a cover wall (4), and a bottom wall (2);

a cylindrical spring receiving space (19) coaxial with the peripheral wall axis and containing a cup spring (20) is configured in at least one of the cover wall (4) and the bottom wall (2); and

that the plate spring (18) is immobilized in its radially external region between a flange (15) of the peripheral wall (3) and the cover wall or bottom wall (4;

2).

4. The tunable cavity resonator as defined in claim 1, characterized in that the adjustment device (22, 26) comprises a manually actuable mechanical actuating element, and a first electromechanical actuating element, downstream from the mechanical actuating element.

5. The tunable cavity resonator as defined in claim 3, characterized in that one or more spacer elements (9;

14) of predefined thickness are arranged between the flange (15) of the peripheral wall (3) and at least one of the bottom wall and the cover wall (2;

4).

6. The tunable cavity resonator as defined in claim 1, characterized in that the tuning plate (28) is made of a dielectric material.

7. The tunable cavity resonator as defined in claim 1, characterized in that a dielectric element (30) is provided in the resonator body (2, 3, 4);

and that

the tuning plate (28) is arranged inside the resonator body (2, 3, 4) at a small distance (d) from a flat surface (29) of the dielectric element (30).

8. The tunable cavity resonator as defined in claim 7, characterized in that the dielectric element (30) is mounted on a displaceable base (10) whose height can be modified by means of a second electromechanical actuating element.

9. The tunable cavity resonator as defined in claim 1, characterized in that at least one of a first and a second electromechanical actuating element (11;

26) receives an electrical control signal, output by an activation circuit, by means of which the cavity resonator (1) is operated in a closed-loop frequency control mode.

10. The tunable cavity resonator as defined in claim 1, characterized in that the cavity resonator (1) is thermally connected to an external cooling device.

11. A tunable microwave oscillator comprising a cavity resonator as defined in claim 1, said tunable microwave oscillator further comprising an amplifier (40) which outputs an amplifier signal (41) that excites the cavity resonator (1), and a phase shifter (45) which receives an output signal (44) coupled out from the cavity resonator (1) and makes available a feedback signal (46), phase-shifted with respect to the output signal (44), which is delivered to an input of the amplifier (40).

12. The tunable microwave oscillator as defined in claim 11, characterized in that the cavity resonator (1) has a quality Q>

10⁶; and

that the conversion ratio mechanism (18, 20) of the cavity resonator (1) is designed in such a way that the minimum change in the resonance frequency (Δ

ω

_R(min)) achievable by a minimum possible displacement of the adjustment device (22) is less than the maximum frequency excursion (Δ

ω

_R) of the resonance frequency (OR) achievable by a displacement of the phase shifter (45).

13. The tunable cavity resonator as defined in claim 4, wherein said manually actuable mechanical actuating element is a rotary actuating element (22).

14. The tunable cavity resonator as defined in claim 4, wherein said first electromechanical actuating element is a first piezoelement (26).

15. The tunable cavity resonator as defined in claim 6, wherein said dielectric material is sapphire.

16. The tunable cavity resonator as defined in claim 8, wherein said second electromechanical actuating element is a second piezoelement (11).

17. The tunable cavity resonator as defined in claim 10, wherein said external cooling device is a mechanical miniature cooler.

18. The tunable microwave oscillator as defined in claim 12, wherein said cavity resonator (1) has a quality Q>

10⁷.