PURPOSE: To make the filter small by employing a 1st dielectric material whose temperature coefficient with respect to its resonance frequency is positive for a 1st dielectric base and a 2nd dielectric material whose temperature coefficient with respect to its resonance frequency is negative for a 2nd dielectric base.
CONSTITUTION: A 1st dielectric material whose temperature coefficient with respect to its resonance frequency is positive is employed for a 1st dielectric base 1 and a 2nd dielectric material whose temperature coefficient with respect to its resonance frequency is negative is employed for a 2nd dielectric base 11. Thus, the dielectric materials whose temperature coefficient with respect to its resonance frequency has a different sign are used for one and same filter, then even when the absolute value itself of the temperature coefficient of the dielectric material is large, the temperature coefficients of resonance conductors 3 between the 1st and 2nd dielectric bases 1, 11 are cancelled with each other. Thus, even when the dielectric bodies whose absolute value of temperature coefficient with respect to its resonance frequency is large are in use, the absolute value of the temperature coefficient in practical use of the filter is decreased. Thus, the filter is made small in size.
HIRAI TAKAMI
FUKAI TETSUYA
SARUKAWA YUJI
SOSHIN ELECTRIC