개방스터브와 분리형 링 공진기를 이용한 마이크로스트립 대역통과필터

Abstract

In this paper, a new microstrip bandpass filter is proposed and implemented using two bandstop filters and a highpass filter. The two bandstop filters are realized by open stub and split-ring resonator, respectively, and a highpass filter is realized by a coupled transmission line.

The lower cutoff frequency of the bandpass filter was decided by the bandstop frequency of the open stub bandstop filter, and also the upper cutoff frequency of the bandpass filter was decided by the bandstop frequency of the split-ring resonator. And the coupled transmission was used as a highpass filter to cutoff DC and the frequency near DC.

The proposed bandpass filter was fabricated on the dielectric substrate with a dielectric constant of 3.5 and the thickness of 0.762mm. The measured results of the filter show that the passband is from 3.99 GHz to 8 GHz and the insertion loss is 1dB.

The bandwidth of proposed bandpass filter can be easily controlled by using the two bandstop frequencies, respectively. It may be useful to design bandpass filter for various communication system.