A novel dual-band matching network using modified T-shaped line and its application

In this paper, a novel design of dual-band matching network using T-shaped coupled line is presented. The main aim of the proposed network is to match unequal frequency-dependent complex loads to a real 50 Ω source impedance at two arbitrarily chosen frequencies. Simple and exact design formulas are obtained by using lossless transmission line analysis. To validate the analysis, four examples of dual-band matching network are designed for different complex loads and frequency ratios. The return loss of the dual-band network is better than 20 dB for all the examples. The proposed network is then applied to match the input impedances of the microstrip patch antenna at two different operating frequencies. A prototype of the rectangular patch antenna working for WLAN and WiMAX applications is fabricated and tested. The measured results are consistent with the simulated results.