CAO Liangzu, YIN Lixia
(Jingdezhen Ceramic Institute , Jingdezhen 333403, Jiangxi, China)

Abstract: In order to reduce grinding precision and improve the qualified rate of dielectric ceramic filters, a technology by which a silver layer is plated at the open-circuited end of the filters is proposed. This paper studies the tuning properties of dielectric ceramic filters with a silver layer at the open-circuited end. The simulated results show that the plating at the open-end not only effectively lowers the resonant frequency of dielectric ceramic resonators and filters, but also increases or decreases the coupling coefficient. The filters made of dielectric ceramics with permittivity of 74 are fabricated and measured, the centre frequencies of the filters are tuned from 1.219 GHz to 1.081 GHz,and the bandwidths of the filters can vary from 9 MHz to 30 MHz.

Key words: bandpass filter; dielectric ceramic resonator; dielectric ceramic filter; tuning property