Diplexer design for switched frequency diversity applications in wireless communications systems

This article concentrates on frequency diversity techniques, considering transmit diversity schemes where there is a single transmitter antenna and a single receiver antenna. Two different carriers are generated by the transmitter and modulated by the same data signal, then the two modulated carriers are transmitted at the same time. At the receiver, the two modulated carriers are also received at the same time. Then, a diplexer is needed to separate these two carriers. In this paper, the diplexer is designed and implemented in X-band frequency. The two branches of the diplexer are designed using a waveguide Y junction to equally split the received signal. Each branch consists of a cylindrical cavity filter for each carrier. The simulation of the diplexer is done using CST software. Simulation results are presented. After that, the implementation has been realized in waveguide technology. Then measurement results are presented, and compared to simulation results. Finally specifications for switched frequency diversity applications in wireless communications systems are verified.