Stepped-impedance based dual-band and dual-function balun for 20 / 44 GHz applications

Dual-band baluns with impedance transforming properties are discussed in this paper for millimeter-wave applications. Based on the even-odd mode analysis and ABCD-matrix, specific design equations are given for the proposed structure. A prototype working at 20 / 44 GHz is presented. The simulations results match well with the theoretical predictions. It is then fabricated and tested. Measurement results verify theoretical predictions.