Microstrip miniaturized loop-filters with high out-of-band rejection for future 3G mobile terminals

摘要

This paper deals about the implementation of miniaturized microstrip band-pass filters operating on a very narrow bandwidth. We propose an original synthesis for achieving high out-of-band rejection by means of a 2nd order resonant structure, for which transmission zeros are introduced through mutual coupling effects. Quite good performances are obtained regarding losses, size and spurious resonances for the proposed topology, which can be considered as a good solution for future mobile on-board equipments.