The design and analysis of PIN diode SPDT Switch and feeding circuit for Security Purpose Pulse Doppler Radar

This paper describes the design, analysis and measured performance of PIN diode Single-Pole Double-Throw (SPDT) Switch and its feeding circuit. The SPDT switch is done for the prototype implementation of The Security Purpose Pulse Doppler Radar which is intended to be used for security applications. Shunt-Shunt Switch topology which includes two cascaded quarter-wavelength sections that each one is terminated by a shunt diode is chosen in order to achieve high isolation between transmit and receive port. The switch feeding circuit is designed and manufactured successfully for pulse generation. Also, 12V to 6V bias converter circuit designed for the switch ground. Since the prototype gets continuous power from Tx port, it produces pulses successfully when it operates in Tx mode. As a result, the circuit can be used as a switch and a pulse generator in the Security Purpose Pulse Doppler Radar system for the 1.2-1.25 GHz frequency range.