Coil Pulsers for Radar

ADAR systems in current use radiate short bursts of energy developed by pulsing a high-frequency generator, usually a magnetron. One means of developing the requisite impulses employs a non-linear coil and is termed a coil pulser. Such pulsers are found in substantial numbers among the Navy's complement of precision radars. Most fire control radars on surface vessels are equipped with them, and all modern radar installations on submarines are so equipped for search and for torpedo control. HISTORY OF DEVELOPMENT Coil pulsers had their origin in the magnetic harmonic generators first built for the telephone plant. Multi-channel carrier telephone systems in general use throughout the Bell System require numbers of carriers, harmonically related in frequency. These are derived from non-linear coil circuits 1 which c o n v e r t energy supplied by a sine w a v e i n p u t into regularly spaced, sharply peaked pulses. When development was started on precision radars, one of these circuits generating a power peak of a few hundred watts, several microseconds in duration, was adapted to the purpose. 2 Its output was shaped and amplified by vacuum tubes of sufficient power to key or modulate the ultra-highfrequency generator of the radar transmitter. All early fire-control radars were made up in this way; hundreds are still in use. The next development of pulsers for fire-control radars was directed toward higher-powered pulses, shorter in duration for good range resolution. These had to be provided by a small package pulser, small enough and rugged enough to mount integrally with the magnetron and the antenna.