The PIN Diode As a Microwave Control Element

Abstract

Switching and phase shifting are done, in the past with mechanical or electromechanical devices . With the advent of ferrite and PN junction semiconductor devices these operations can be carried out at speeds of at least two or three orders of magnitude faster than with electromechanical devices. In the case of ferrites , the control operations are carried out by changing the magnitude & direction of an externally applied magnetic field to the ferrite. In the case of PN junction semiconductor devices , the control is achieved by varying the bias current or bias voltage across the solid state devices. Of the several PN junction devices available , the PIN silicon diode is the most widely used for two state (digital) microwave control operation . The applications of junction diodes to microwave switching and phase shifter are numerous and varied . One example is the switching of the power of RF source to several antennas or performing duplexing in a radar system. Another application of PIN diode and perhaps the most important application is the possibility of electronically steering phase array antennas using PIN diode phase shifters.