Filter with temperature compensated tuning screw

(19)

(11)

EP 0 883 203 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	27.10.1999 Bulletin 1999/43

(43)	Date of publication A2:
	09.12.1998 Bulletin 1998/50

(21)	Application number: 98304360.5

(22)	Date of filing: 02.06.1998

(51)	International Patent Classification (IPC)⁶: H01P 1/208, H01P 1/30, H01P 7/06

(84)	Designated Contracting States:
	AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
	Designated Extension States:
	AL LT LV MK RO SI

(30)

Priority:

02.06.1997 CA 2206942

(71)	Applicant: COM DEV LTD.
	Cambridge, Ontario N1R 7H6 (CA)

(72)	Inventors:
	Lundquist, Steven Barton Cambridge, Ontario, N1R 8H4 (CA) Zybura, Andre J. Kitchener, Ontario, N2M 2VG (CA)

(74)	Representative: Warren, Anthony Robert et al
	BARON & WARREN, 18 South End, Kensington London W8 5BU London W8 5BU (GB)

(54)	Filter with temperature compensated tuning screw

(57) A temperature compensated filter has a compensating screw (18) mounted in a support (40) in the wall (22) of a cavity. The support is made from a material having a high coefficient of thermal expansion compared to the material of the cavity and the material of the compensating screw. As temperature changes, the support moves the compensating screw either further into the cavity or further out of the cavity to compensate for the change in resonant frequency of the cavity that would otherwise occur. The compensating screw can be used with single, dual or triple mode cavities. The compensating screw can be made of metallic material or it can be made of non-metallic material with a metallic outer surface. The compensating screw is locked in the support before the support is inserted into the wall of the cavity. The support is then locked in the wall of the cavity and the screw automatically changes position within the cavity as temperature changes. An RF barrier (50) can be used to prevent RF energy from the cavity from entering the area of the support.

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