Dual-band microstrip-to-coplanar strip balun transition and loop antenna application

Abstract

A microstrip-to-coplanar strip balun transition and its applicability to a single-fed dual-band tapered loop antenna are presented. The dual-band transition consists of a simple two-section transmission-line transformer and a two-section open-ended line. Closed-form design equations based on ideal transmission lines are derived and then verified with the examples of two designs. The application of the transition to a single-fed 0.9/1.8 GHz dual-band tapered loop antenna is then demonstrated. The measured performance of the antenna proves the validity of the proposed dual-band transition network.