Design of an ultra-compact lowpass filter with ultra-sharp roll-off for UHF application

Abstract

This letter proposes a UHF lowpass filter based on the image parameter method. This study designed, fabricated and assembled a 0.48-GHz semilumped lowpass filter using low cost FR4 substrate. It adopted a new layout concept for the air wound coils to achieve the purposes of compact size and good performances. The proposed UHF lowpass filter has the best performances for the roll-off rate and circuit size compared to previous works, and it also achieves the best figure of merit 973,369.