Chapter 15 - Microwave Solid-State Switches, Phase Shifters, and Attenuators

Abstract

This chapter deals with microwave solid-state switches, phase shifters, and attenuators. A microwave switch is basically a device that turns microwaves on and off. As for solid-state switching devices, transistors and diodes are logical candidates. Because of the simplicity and cost-effectiveness, most microwave solid-state switching devices practically in use are PIN junction diodes. The diode is operated under forward DC bias conditions to close the diode switch. When the diode is forward biased sufficiently, the diode resistance is very small and it presents very little loss for microwaves to propagate through. The attenuation of microwave power through the switching diode is essentially termed as the insertion loss. The chapter also discusses switching configurations namely single pole single throw (SPST), single pole double throw (SPDT), single pole multiple throw (SPMT), and other transfer switches. The important part of a microwave solid-state phase shifter is a reverse biased varactor diode or the variable capacitance diode. The chapter also analyses microwave solid-state attenuators. Forward biased PIN diodes are employed for microwave solid-state attenuators.