A novel quad-band impedance transformer with ultra-high transforming ratio

This paper presents a novel design of ultra-high transforming ratio quad-band impedance transformer. This transformer is capable of matching a very high real load (ZL) to the source impedance (ZS) of 50Ω at four different operating frequencies. The proposed structure is constructed using two series transmission line separated by a H-shaped network. The analytical relationship between various design parameters are obtained using ABCD matrix method to provide a accurate solution. To validate the derived formulas, two prototype of the quad-band transformers with impedance transforming ratios of 10 and 20 are designed, fabricated, and tested. The measured return loss is greater than 15 dB at all operating frequencies. The measured results are consistent with the simulated and theoretical calculations.