SIZE REDUCTION OF KLOPFENSTEIN-BALUN TRANSFORMER FOR BALANCED ANTENNAS

Abstract

A BALUN transformer converts impedance into another one and also converts an unbalanced line into a balanced line. A compact size broadband BALUN transformer is designed using Klopfenstein taper line transformer approach to transform 50Ω impedance into 100 Ω. The results of the conventional BALUN are compared with the proposed compact size BALUN. In order to reduce the length of the BALUN, a curved microstrip line is used. The proposed compact size BALUN is 56 %- 70 % smaller in size w.r.t the conventional BALUN but at the cost of 6% - 11% reduction in the overall band. The conventional BALUN has measured % bandwidth of 165 while the reduced size BALUN has 159. The measured results are in agreement with the simulated results.