Abstract: The present invention is to overcome a problem of a variation in a resonant frequency of a microwave stripline filter which may occur at a change of temperature during when the microwave stripline filter is operated. The microwave stripline filter has resonator electrodes (3 and 4) with a predetermined pattern provided between a pair of dielectric substrates (1 and 2), one of the dielectric substrates is formed by ceramic material whose temperature coefficient of resonant frequency is negative, and the other substrate is formed by a ceramic material whose temperature coefficient of resonant frequency is positive, which results in that the mutual temperature dependency to the resonant frquency in the paired dielectric substrates can be cancelled, and thus it is possible to feasibly hold the temperature coefficient of the filter device to zero. The stripline filter according to the present invention can conveniently utilized as a band-pass filter for miniature electronic circuits.

Abstract: A dielectric resonator device comprising a resonator body having a dielectric resonator element of dielectric ceramics, and a supporting member integrally formed with the resonator element and made of the same material as that of the resonator element, the resonator element being provided with an inner hole, if necessary.

Abstract: A ceramic filter with planar, piezoelectric-type resonators and planar inputting, outputting, and grounding terminal boards arranged in parallel relationship in an insulating case with respective edges extending toward an open case side. Terminal legs extending from the respective edges are received in appropriately positioned and configured holes in an insulating lid which closes the case. Outer surface of the lid includes metalized areas for electrically connecting to the terminal legs and for connecting to an external circuit board.