Six-Port Coupler Design for High-Power Radio Frequency Applications

Design, simulation, and implementation of six-port couplers for high-power radio frequency applications using transformer coupling is given for the first time. The complete analytical model for six-port coupler is developed, and closed-form equations using operational and scattering parameters are presented. The design is verified using time- and frequency-domain simulators. The design accuracy is increased using an accurate inductor model that is used for transformer construction. Final design is implemented and measured with network analyzer, HP8753ES. It has been observed that the analytical, simulation, and measurement results are all in agreement. It is confirmed that the proposed six-port coupler using transformer coupling gives the required coupling, isolation, and directivity levels in the forward and reverse modes, which make it an accurate power measurement device that can also be used to measure voltage, current, and impedance and hence function as a reflectometer. MATLAB Graphical User Interface (GUI) to design six-port directional couplers has been developed for academic and commercial use with implementation of the analytical model developed in this paper.