Temperature compensated high power bandpass filter

A bandpass filter comprising:

• a waveguide cavity in which an input electrical signal resonates at a desired resonant frequency, the cavity having a plurality of surfaces each with a predetermined geometric shape, a first one of the surfaces being subject to thermal expansion upon an increase in filter temperature, said thermal expansion resulting in an increase in dimensions of the cavity;
• and
• a thermal compensator comprising:
• a control rod having a first end fixed to a predetermined location on a housing of the filter and a second end apart from the first end in a direction of said thermal expansion, the control rod having a coefficient of thermal expansion significantly different than that of the first surface;
• and
• a deflecting rod having a first end fixed, in the thermal expansion direction, relative to the second end of the control rod, the deflecting rod limiting movement of a point on a second one of said surfaces in thea first direction such that, in response to thermally-induced changes in dimensions of the cavity, the shape of the second surface is distorted to counteract an increase in cavity dimension.

A bandpass filter having a normal operating temperature greater than ambient temperature, comprising:

• (a) a waveguide cavity;
• (b) an elongated structure located external to said cavity in the ambient environment and having a temperature lower than said operating temperature of said cavity when said cavity is in use, said structure being mechanically coupled to said cavity between two points spaced by a predetermined separation distance,
• i. the structure having a CTE (coefficient of thermal expansion) and an operating temperature relative to the CTE and the operating temperature of said cavity which causes said separation distance between the points on the cavity to expand or contract more than said structure expands or contracts across said separation distance when the operating temperature of the cavity changes,
• (c) the resulting temperature-induced dimensional differences between said structure and said cavity across said separation distance creating temperature-dependent mechanical movement of said structure relative to said cavity which is employed to reduce the frequency drift of said cavity with variations in operating temperature.

A bandpass filter having a normal operating temperature greater than ambient temperature, comprising:

• (a) a waveguide cavity;
• (b) an elongated structure located external to said cavity in the ambient environment and having a temperature lower than said operating temperature of said cavity when said cavity is in use, said structure being mechanically coupled to said cavity between two points spaced by a predetermined separation distance,
• i. the structure having a CTE and an operating temperature relative to the CTE and the operating temperature of said cavity which causes said separation distance between the points on the cavity to expand or contract more than said structure expands or contacts across said separation distance when the operating temperature of the cavity changes,
• (c) the resulting temperature-induced dimensional differences between said structure and said cavity across said separation distance creating temperature-dependent mechanical movement of said structure relative to said cavity which is employed to deform cavity and thereby to reduce the frequency drift of said cavity with variations in operating temperature.