초소형 마이크로 스트립 대역통과 필터

Abstract

Miniaturized microwave bandpass filters are always in demand for systems requiring small size and light weight. This demand is much increased recently by rapidly expanding cellular communication systems.

In this thesis, a novel miniaturized UHF bandpass filter using diagonally end-shorted coupled lines and lumped capacitors is proposed. With this new method, the size of the bandpass filter can be reduced to just a few degrees without sacrificing the characteristics of the conventional filter at the operating frequency. In addition to it, this new filter also shows a wider upper stopband.

A two-stage bandpass filter using this method has been designed and fabricated at a midband frequency of 300 MHz with electrical length of 5.2°. Both theoretical and experimental performances are presented. The total physical size of the fabricated filter is only 17 mm, 95% reduced compared with the conventional one. The fabricated filter exhibits good filtering characteristics with a wider upper stopband. This extremely miniaturized band-pass filter holds promise for MMIC (Monolithic Microwave Integrated Circuits) technologies which can be applied to mobile communications and other applications.