This research presents a 2×2 Switch Matrix based on PIN diode switching elements custom design. It operates at the 3.3-3.8 GHz frequency band and it is integrated in the RF Front End of a prototype WiMAX Relay Station. It provides low insertion loss and high isolation and implements Time Transmit & Receive, alternatively Simultaneous Transmit & Receive operation in Time Domain Duplexing mode according to the IEEE 802.16j standard.