Design of multi-band microstrip power dividers

A survey of design methods of multi-band microstrip power dividers is presented. It can be found that the basis of multi-band power divider design is the design of multi-band impedance transformers. In fact, the quarter-wavelength transmission lines are usually used directly to realize multi-band power divider. Another design approach of a multi-band power divider is to attach an impedance transformer to each port of its junction, in which the impedance transformer transforms the equivalent admittance of a three-port junction to normalized unit conductance at multiple-frequencies. Some multi-band power dividers including a novel dual-band or broadband Gysel power dividers are discussed.