Aperture compensation and multipole generation techniques leading to the emergence of a new planar filter

Aperture compensation technique is developed for achieving effectively strong coupling strength in the parallel-coupled microstrip line (PCML). This PCML is in this work characterized by an equivalent J-inverter network with the use of our SOC de-embedding technique self-contained in our fullwave MoM algorithm. Extracted parameters indicate that the coupling strength appears frequency-distributed and its maximum value rapidly rises up as the aperture becomes widened. Then, a pair of capacitively loaded line section is inserted between two identical PCML to formulate a new planar bandpass filter with multi-pole bandpass behavior. Our predicted and measured results show attractive properties of the proposed filter with BW=60%, |S₁₁|<-16 dB and 220% wide up-band of rejection