Temperature compensated coaxial resonator having inner, outer and intermediate conductors

Claim 1

A temperature compensated, coaxial cavity resonator comprising, a first, outer conductor of a hollow structure, a second, inner conductor internally disposed in a coaxial relationship with said first conductor and in a short-circuit connection at one end thereof with one end wall of said first conductor and in an open-circuit relationship with the other end wall of the first conductor, and a third, inner conductor of a hollow structure coaxially disposed with and encircling said second conductor, said third conductor having a closed end which is connected to the open-circuit end of said second conductor and the axial extent of said third conductor being smaller than the axial extent of said second conductor, said first conductor having a thermal expansion coefficient equal to or greater than the thermal expansion coefficient of said second conductor and greater than the thermal expansion coefficient of said third conductor, longitudinal expansion of said first, second and third conductors as a function of temperature being electrically compensated by transverse expansion as a function of temperature of said first and third conductors, whereby said resonator has a resonant frequency that is substantially independent of temperature.