| ABSTRACT:
An impulse radar that forms a predetermined radar pulse train in
space by transmitting individual spectral components thereof. Thus, a train
of extremely short pulses is obtained without switching a radio frequency
signal on and off at a high rate. An oscillator is coupled to a harmonic
generator, and a power divider distributes the output of the harmonic generator
to a multiplicity of amplifiers. Each amplifier has a phase-locked VCO
circuit that provides frequency accuracy, spectral purity, low noise and
frequency stability. Thus, each amplifier provides one of the spectral
components of the predetermined radar pulse train. The amplifiers are coupled
to a multiplexing feed that illuminates a reflector. On receive, the multiplexing
feed separates the spectral components of the incoming pulse train. Each
spectral component is coupled to its own narrow band receiver, and one
receiver is used to amplify and detect each spectral component. The signals
from the receivers are coherently combined in asignal processor in which
the signals add coherently and the noise signals do not. The output of
the signal processor may be applied to a radar display. The short pulses
produced by the radar provide very high resolution, and can map a target
by sweeping across it, thus imaging it. The radar emits a wideband signal
at a low power level; the signal is difficult to detect and intercept,
and thus provides for a low probability of intercept radar. The radar may
be used as a microwave link, wherein the oscillator may be frequency modulated
to provide communications. It may also be used a covert IFF system to identify
friendly aircraft. The radar provides signals that penetrate sand and may
be used for mapping and to locate land mines buried in the sand. It may
also be used for clearing away land mines by detonating them. When the
power is turned up, the radar provides for a directed energy beam. The
radar may perform adaptive jamming, and is also a jam resistant radar.
It is hard to jam because the receiver array is insensitive to noise at
frequencies outside the narrow bandwidths of the individual receivers and
also to noise which is not coherent across the multiplicity of receiver
channels. |