The silicon PIN diode as a microwave radar protector at megawatt levels: Theory

A silicon intrinsic barrier (PIN) diode can give good protection against pulse burnout of microwave radar receivers. For best operation, external bias should be supplied to energize the diode (switch operation), rather than self-bias from the pulses (limiter operation). Since the device operates by charge-controlled conductivity modulation, comparatively small amounts (Milliamperes) of dc bias current can control large amounts (amperes) of microwave current. Protection levels of greater than 50 db are predicted from an analysis of silicon wafer performance. At present, protection actually obtained is limited by the inductance of the encapsulation to about 44 db. Power calculations indicate that a pair of diodes should be able to protect against pulse energies as high as 20 megawatt-microseconds without burnout.