A compact dual‐band frequency‐dependent impedance transformer using two resizable shunt stubs. Issue 3 (11th December 2021) - Wan, Zipeng
Abstract: This paper presents a dual‐band impedance transformer for frequency‐dependent loads with two resizable shunt stubs. The proposed transformer is composed of a single‐band matching network and a dual‐band susceptance stub network (DSSN). The single‐band matching network only consists of a one‐section matching network when the load is within the derived circle areas. The design parameters of the DSSN can be adjusted freely. The bandwidths at the two bands can be enhanced, and the possibility of using transmission lines with extremely high or low impedance is reduced significantly. All the parameters are obtained by solving the analytical design formula. Two examples are presented for illustrating the design process, and a prototype is fabricated and measured for verification. Good agreement between the simulation and the measurement is obtained. Compared with the previous works, the transformer not only has the shortest electrical length but also obtains wide bandwidths. Therefore, the transformer is very applicable for dual‐band systems, especially the dual‐band active device circuits.