Apparatus and method for providing temperature compensation in Te.sub.101 mode and Tm.sub.010 mode cavity resonators
AssigneeRadio Frequency Systems, Inc.
InventorsPitt W. Arnold, Tage V. Jensen
Life of this patent
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Abstract
A TE.sub.101 mode cavity resonator housing 60 has a truss 70 securely mounted to one of its broadwalls 72. The truss 70 is fabricated from a material having a lesser coefficient of expansion than that of the material from which the housing 60 is fabricated. The difference between the coefficients of expansion results in a difference in expansion and contraction of the materials over temperature. The thermal expansions and contractions in the housing 60 material result in variations in the natural resonant frequency of the housing 60. These variations in natural resonant frequency are compensated by offsetting thermal expansions and contractions in the truss 70 material.
Claims25
An apparatus for providing temperature compensation in a high frequency cavity resonator, said apparatus comprising in combination:
- a cavity resonator housing having a high conductivity interior surface enclosing a region wherein electromagnetic fields may freely propagate, said housing being fabricated from a material having a specific coefficient of expansion, said fabricated housing having a natural resonant frequency;
- coupling means for providing an input and an output connection to said enclosed region of said cavity resonator housing;
- and
- temperature compensation means in the form of a truss having a center section and a plurality of limbs extending therefrom, said temperature compensation means being physically secured to and electrically contacted with said interior surface of said cavity resonator housing at the end of each of said plurality of limbs, said temperature compensation means being fabricated from a material having a lesser specific coefficient of expansion than said cavity resonator housing material, said lesser specific coefficient of expansion resulting in a lesser thermal expansion or contraction of said temperature compensation means material than said cavity resonator housing material, said lesser thermal expansion or contraction resulting in a forced relative movement of said temperature compensation means with respect to said cavity resonator housing, said forced relative movement resulting in a first variation in said natural resonant frequency, such that said first variation in said natural resonant frequency compensates for a second variation in said natural resonant frequency caused by a thermal expansion or contraction of said cavity resonator housing material.
A method for providing temperature compensation in a high frequency cavity resonator, said method comprising the steps of:
- supplying a cavity resonator housing having a high conductivity interior surface enclosing a region wherein an electromagnetic fields may freely propagate, said housing being fabricated from a material having a specific coefficient of expansion, said fabricated housing having a natural resonant frequency;
- providing an input and an output connection to said enclosed region of said cavity resonator housing;
- fabricating a temperature compensation means in the form of a truss having a center section and a plurality of limbs extending therefrom, said temperature compensation means being fabricated from a material having a lesser coefficient of expansion than said cavity resonator housing material, said lesser coefficient of expansion resulting in a lesser degree of expansion and contraction of said temperature compensation means material over temperature;
- positioning said temperature compensation means along said interior surface of said resonant cavity housing, said position of said temperature compensation means being determined by said natural resonant frequency of said cavity resonator housing, said coefficient of expansion of said cavity resonator housing material, and said coefficient of expansion of said temperature compensation means material;
- and
- securing said temperature compensation means in said determined position along said interior surface of said resonant cavity housing at the end of each of said plurality of limbs so as to create an electrical contact between said temperature compensation means and said cavity resonator housing, said secured position of said temperature compensation means resulting in a non-uniformity in a critical dimension within said enclosed region of said cavity resonator housing, said non-uniformity in said critical dimension varying over temperature as a result of said lesser coefficient of expansion, said variation in said non-uniformity in said critical dimension resulting in a first variation in said natural resonant frequency, such that said first variation in said natural resonant frequency compensates for a second variation in said natural resonant frequency caused by expansions and contractions of said cavity resonator housing material over temperature.
Dependencies are inferred from the claim text.