A new wideband planar bandpass filter consists of
two series wire-bonded multiconductor transmission lines (MTL) and a shunt short-circuited MTL is presented and analyzed. A
comprehensive study of the proposed topology is carried out and it is assessed that three-pole wideband bandpass filters with two transmission zeros on both sides of the passband can be readily
designed. Besides, it is demonstrated that the frequency response of these filters depends exclusively on the coupling factors of
both series and shunt MTLs and some design rules are given to optimize the in-band flatness and enhance the roll-off slopes at cut-off frequencies. In order to validate the theoretical results, a passband filter is designed, fabricated and measured.