Coupled Line Filters Using Via-Less End-Connected Broadside Coupled Asymmetric Coplanar Striplines

End-connected broadside coupled asymmetric coplanar stripline (ACPS) is proposed and characterized through conformal mapping for application in via-less coupled line filters. The exact similar derived parameters to the conventional ACPS indicate feasibility of using end-connected broadside coupled ACPS in ACPS applications. The end connection can be implemented using copper foil to eliminate the need for vias. Three coupled line filters for different bandwidths of 50%, 75%, and 100% with 1.7-1.85-dB insertion loss are fabricated and measured to demonstrate feasibility. To further improve the selectivity of the filter, a transmission zero is introduced below the passband by adding an inductor.