| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress a change in an operating frequency due to ambient temperature at a low cost without using a circuit for a heart and its temperature control section or the like. SOLUTION: A screw 22 is fastened to a casing 12 in a state such that the screw 22 is close to an open end of an open stub 14 surface-mounted on a dielectric board 13, and a thermal expansion coefficient of the kind of material of this screw 22 is selected smaller than a difference between a thermal expansion coefficient of the kind of material of the casing 12 and a thermal expansion coefficient of the kind of material of the dielectric board 13. For example, an aluminum (thermal expansion coefficient = 23) is employed for the casing 12, an alumina (thermal expansion coefficient = 6) is for the board 13 and an invar (thermal expansion coefficient = 1) is used for the screw 22. Thus, the frequency is kept constant because the screw 22 is parted from the open end of the open stub 14 resulting in causing a capacitance change when the frequency is decreased by the open stub 14 extended by a temperature change.</p> |
