An Enhanced Frequency Ratio Dual Band Balun Augmented With High Impedance Transformation

Design of a dual-band balun achieving simultaneous high impedance ratio (> 20) and band-ratio (> 10) is reported in this brief. The presented design, augmented with closed-form design equations and a systematic design procedure, achieves excellent isolation between output ports and good matching at all the ports. A number of case studies are included to demonstrate the capability of the presented approach for varying design specifications and port-terminations. A prototype is developed for impedance transformation ratio (k) of 5 and frequency ratio (r) of 5 concurrently to evaluate the presented design approach show excellent agreement between the simulation and experimental results and thus validate the proposed design strategy. A comparative analysis with a number of recently reported dual-band impedance transforming components demonstrates superior performance of the proposed design.