A Generalized Dual-Frequency Transformer for Two Arbitrary Complex Frequency-Dependent Impedances

The purpose of this letter is to propose a dual-frequency transformer for two arbitrary complex frequency- dependent impedances (ACF-DIs) and present a generalized T-junction power divider (T-JPD) operating at dual-band with arbitrary power-dividing ratios based on the proposed transformer. By the rigorous analysis of transmission line theory, the closed-form design equations for this generalized transformer are obtained. Using the analytical design method, a kind of generalized T-JPD can be designed to operate at two different frequencies with different power-dividing ratios. Furthermore, numerical examples are simulated and a microstrip T-JPD operating at 1 and 2.4 GHz with different power-dividing ratios (1.5 and 2 dB, respectively) is fabricated. Good agreements between the simulated and measured results can be observed.