The Electron Beam Parametric Amplifier as a Radar System Component

Practical experience is now available with the Electron Beam Parametric Amplifier (EBPA) used as a low-noise preamplifier in radar systems. Principles of operation of the EBPA are briefly recapitulated. Among its desirable characteristics are unilateral behavior, high stable gain and a double-channel noise figure (NF) of 1 db or less; its bandwidth, input and output impedance remain constant as gain is adjusted. An L-band amplifier is described in detail. A discussion of various ways of handling the idler channel follows. The technique of in-pass-band pumping achieves an effective NF of 2.5 db or better in radars with conventional detection. Complications arise with Moving Target Indicator (MTI) systems; remedies are described. The paper reports on field tests in which these techniques were used, including a few flight tests. The results show substantial improvements in sensitivity and range. They also spotlight the ability of the EBPA to tolerate high overload and to act somewhat like a TR switch.