Thermally compensating microwave cavity

• US 5,329,255 A
• Filed: 09/04/1992
• Issued: 07/12/1994
• Est. Priority Date: 09/04/1992
• Status: Expired due to Fees

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Hayes, James R., Purden, George J., Kasten, Steve R.
• Primary Examiner(s): MIS, DAVID C
• Application Number:
  US07/940,580
• Time in Patent Office: 676 Days
• Field of Search: 331/68, 331/69, 331/96, 331/107 DP, 331/176, 331/117 D, 333/229, 333/231, 333/232, 333/233
• US Class Current: 331/96
• CPC Class Codes: H01P 7/06 Cavity resonators
• CPC Class Codes: H03B 2009/126 using impact ionization avalanche transit time [IMPATT] diodes
• CPC Class Codes: H03B 9/145 the frequency being determined by a cavity resonator, e.g. a hollow waveguide cavity or a coaxial cavity H03B9/141 - H03B9/143, H03B9/147, H03B9/148 take precedence
• CPC Class Codes: H03L 1/021 of generators comprising distributed capacitance and inductance

Abstract

A thermally compensating microwave cavity is provided. An active device that generates microwaves is disposed within this microwave cavity such that microwaves are emitted within the cavity. A first portion of these microwaves travels in one direction from the active device and forms a broad bandwidth signal. A section portion of the microwaves travels toward a reflecting member and is reflected. Once reflected, this second portion combines with and compensates the first portion. A temperature dependent bellows is utilized to displace the active device and the reflecting member relative to one another. Accordingly, as the signal emitted by the active device changes with temperature, the reflecting member is displaced by the bellows to properly reflect the second portion of the microwaves such that it combines with and properly compensates the signal.

Claims

1. A thermally compensating microwave cavity for compensating microwaves passing through said microwave cavity such that a compensated microwave signal is emitted from said cavity, said microwave cavity comprising:

a) at least one member defining a broad bandwidth microwave cavity;

b) generating means for generating microwaves within said microwave cavity such that a first portion of said microwaves, traveling in one direction from said generating means, form a broad bandwidth signal that passes through said microwave cavity;

c) reflecting means for reflecting a second portion of said microwaves, traveling in another direction from said generating means, such that said second portion of microwaves is reflected to combine with and compensate said broadband signal formed by said first portion; and

d) temperature dependent displacing means having a generally hollow expandable member with a fluid material disposed therein that expands and contracts as a result of temperature change, said expandable member operable for causing said reflecting means and said generating means to move relative to one another, as said fluid material expands and contracts, to compensate for changes in said broad bandwidth signal occurring as a result of said temperature change.

2. The thermally compensating microwave cavity of claim 1 wherein said generating means for generating microwaves is an active device.

3. The thermally compensating microwave cavity of claim 1 wherein said hollow expandable member is a bellows that expands and contracts as a result of temperature changes.

4. The thermally compensating microwave cavity of claim 3 wherein said bellows is filled with a silicone material.

5. The thermally compensating microwave cavity of claim 1 wherein said displacing means displaces said reflecting means a distance substantially greater than 0.003 inches.

6. The thermally compensating microwave cavity of claim 1 wherein said generating means is stationary and said reflecting means is displaced relative to said generating means.

7. The thermally compensating microwave cavity of claim 1 wherein said reflecting means and said displacing means are coupled to an attaching means such that said reflecting means and said displacing means can be removably attached as a unit to said member defining said microwave cavity.

8. The thermally compensating microwave cavity of claim 7 wherein said reflecting means is slidingly engaged with said attaching means.

9. The thermally compensating microwave cavity of claim 1 wherein said generating means for generating microwaves within said microwave cavity is an IMPATT diode.

10. A temperature compensating device for compensating microwaves passing through a microwave cavity such that a compensated microwave signal is emitted from said cavity, said device comprising:

a) at least one member defining a broad bandwidth microwave cavity;

b) an active device, that is stationary relative to said member, that generates microwaves within said microwave cavity such that a first portion of said microwaves travels through said cavity away from said active device and a second portion of said microwaves travels through said cavity away from said active device in an opposite direction;

c) reflecting means disposed within said cavity for reflecting said second portion of said microwaves such that said second portion combines with said first portion to form a thermally compensated signal; and

d) an expandable and contractible bellows having a thermal expansion coefficient, said bellows operably associated with said reflecting means for moving said reflecting means relative to the active device as said bellows expands and contracts with changes in temperature.

11. The temperature compensating device of claim 10 wherein said bellows is filled with a silicone material.

12. The temperature compensating device of claim 10 wherein said bellows displaces said reflecting means a distance substantially greater than 0.003 inches.

13. The temperature compensating device of claim 10 wherein said reflecting means and said bellows are coupled to an attaching member such that said reflecting means and said bellows can be removably attached as a unit to said microwave cavity.

14. The temperature compensating device of claim 10 wherein said reflecting means is slidingly engaged with said attaching member.

15. The temperature compensating device of claim 10 wherein said active device within said microwave cavity is an IMPATT diode.

16. The temperature compensating device for compensating microwaves passing through a microwave cavity such that a compensated microwave signal is emitted from said cavity, said device comprising:

a) at least one member defining a broad bandwidth microwave cavity;

b) generating means for generating microwaves within said microwave cavity such that a first portion of said microwaves, traveling in one direction from said generating means, form a broad bandwidth signal that passes through said microwave cavity;

c) reflecting means for reflecting a second portion of said microwaves, traveling in another direction from said generating means, such that said second portion of microwaves is reflected to combine with and compensate said broadband signal formed by said first portion; and

d) temperature dependent displacing means for displacing said reflecting means and said generating means relative to one another, said reflecting means and said displacing means being coupled to an attaching means such that said reflecting means and said displacing means can be removably attached as a unit to said member defining said microwave cavity, said reflecting means slidingly engaging said attaching means as a result of temperature changes in said temperature dependent displacing means, thereby positioning said reflecting means to compensate for changes in said broad bandwidth signal as a result of temperature changes in said generating means.