A dual-band impedance transformer for frequency-dependent complex loads incorporating an L-type network

A novel scheme is presented to realize a matching network working at two arbitrary frequencies. The load is assumed to be complex as well as frequency dependent whereas the source-side impedance is real. There are two possible topologies of the proposed network, thereby being able to cater to a wider range of load impedances. In addition of being relatively miniaturized structures, closed form design equations are also achieved for these designs. Many examples are included to show working of the proposed scheme. A prototype operating at 1GHz/2GHz is designed for validation. The simulated and the measured results exhibit good performance with better than 15dB return loss.