Wide-band bandpass filter using coupled three-line microstrip structure and plane capacitor

A wideband bandpass filter topology is proposed with three plane capacitors attached to the symmetrical coupled three-line microstrip structure. It shows a quasi-elliptic wideband response with two transmission zeros added so as to enhance the selectivity. This structure demonstrates 51% bandwidth with good insertion/return losses, flat group delay, sharp transition, and embedded DC-chock.