Lumped-element impedance-transforming uniplanar transitions and their antenna applications

Novel impedance-transforming coplanar waveguide (CPW)-to-coplanar stripline transitions and CPW-to-slotline transitions are proposed, using planar lumped elements to realize the L-section impedance-matching network in the transition structures. Simple equivalent-circuit models based on closed-form expressions are also established, from which various lumped-element impedance-transforming transitions are investigated. Examples for using the proposed transitions in the design of antenna feeding structures are also demonstrated, and successful size reduction has been achieved.