Abstract: A filter is composed of plural resonators formed on one surface of a dielectric substrate and a ground plane formed on the other surface. A resonant frequency of each resonator is accurately measured individually and independently from other resonators. Other resonators not selected for measurement are all short-circuited or covered with a conductive member to shift their resonant frequency to a region that does not interfere with the resonant frequency of the resonator under measurement. Also, a coupling coefficient of an arbitrary pair of resonators is accurately measured under no interference from other resonators in the similar manner.

Abstract: Plural resonators formed on a dielectric substrate constitute a filter. The resonant frequency of each resonator is adjusted to a target frequency by accumulating dielectric material on the resonator. The degree of such adjustment is substantially proportional to the amount of the dielectric material. The resonators are originally designed to have a resonant frequency that is a little higher than the target frequency. The resonant frequency of each resonator deviates from the designed target because of various factors in manufacturing processes. Each resonant frequency is measured, its deviation from the target is calculated, and the amount of the dielectric material required to eliminate such deviation is determined before the adjustment process. Accordingly, the adjustment is easily performed without measuring the resonant frequency during the adjustment process.

Abstract: Herein disclosed is a band-pass filter for a radio wave having a wavelength range of a high frequency, such as a microwave and a milliwave. The band-pass filter comprises: a dielectric substrate; input and output terminals; and a plurality of conductive strip line resonators being capable of resonating with a predetermined wavelength. Each of the strip line resonators has two ends and bent line extending from one end to the other end with a predetermined length corresponding to the wavelength. The one end and the other end are placed face to face with each other to provide a gap therebetween. In the band-pass filter, the plurality as arranged on the dielectric substrate in series and spaced apart from each other at predetermined intervals along a predetermined position line and coupled with each other through the inductive and capacitive coupling to transfer the signal between the resonators one after another.