Novel design of duplexer for S band applications

This paper presents design and fabrication of duplexer that works for 3 GHz frequency. This system composed of dual band antenna, hybrid coupler as phase shifter and mixer with stubs. Two frequency band for antenna are 3 and 5 GHz. Inclusion of slots with near about symmetrical distribution on conducting plane and notches in both plane and defected ground structure and also changing feed position for impedance matching. Simulation is done using Serenade SV and IE3D softwares for various parameters. Isolation between transmitter and receiver was -65.12 dB of final design and phase difference of almost 180 degree. Both simulated and measured values are reported.