Lumped-Element Impedance-Transforming Uniplanar Transitions and Their Antenna Applications

Abstract

Novel impedance-transforming coplanar waveguide (CPW)-to-coplanar stripline transitions and CPW-to-slotline transitions are proposed, using planar lumped elements to realize the -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.

CPW balun for printed balanced antennas

“…a Layout with voltage and current definitions for even (subscripts 'e') and odd (subscripts 'o') modes b Multimodal circuit model To feed printed balanced antennas (such as dipoles, folded dipoles and quasi-Yagi and bow-tie antennas) in CPW circuits, CPW-to-slotline (or to-coplanar-strips (CPS)) baluns are used [3][4][5][6][7][8]. These baluns may electromagnetically interact with antennas with significant backward radiation, modifying their radiation pattern and input impedance, and thus the matching of the circuit, so it is difficult to design the balun independently of the antenna.…”