Design of a Narrow-Band Bandpass Filter Using Microstrip Open-Loop Resonators With Coupled and Crossing Lines

결합 및 교차 선로를 갖는 마이크로스트립 개방루프 공진기를 이용한 협대역 대역통과 여파기 설계

  • Published : 2001.09.01


In this paper, a narrow-band bandpass filter using microstrip open-loop resonators with coupled and crossing lines is designed and fabricated. This filter has many advantages such as compact in size, low weight and the characteristic of the elliptic-function narrow-band bandpass filtering. The configuration consists of two identical microstrip open loop resonators, coupled line and crossing line. By using open loop resonators, the size of the filter can be reduced about 50% compared with the ring resonators. A crossing line gives two notchs in the stopband, which have sharp selectivity in the passband. Centered at 2.455GHz, the calculated microstrip bandpass filter shows a bandwidth of 1.22%, which makes it very attractive for application in the wireless LAN. The filter is fabricated by photo-etching process. The fabricated bandpass filter shows that the bandwidth is 0.85% for 2.458GHz and the size is only $2.6cm\times1cm$.