A Wideband Filtering Complex Load Impedance Transformer with Equal-Ripple Level

In this letter, a wideband filtering impedance transformer (IT) with an equal-ripple level is proposed for matching a complex impedance to 50 $\Omega$. It consists of two short-circuited stubs, one open-circuited stepped-impedance stub, and two parallel-coupled lines (PCLs). When two port impedances are provided, the relationship between the equal-ripple level of Sii and the characteristic impedances of proposed IT can be established. To validate the proposed theory, three examples of IT are designed. One of them is fabricated and measured. The measured results matched well with the simulated ones.