| 摘要 |
<p>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 (80) is coupled to a harmonic generator (111), and a power divider (62) distributes the output of the harmonic generator to a multiplicity of amplifiers (63). Each amplifier (63) has a phase-locked VCO circuit (114) that provides frequency accuracy, spectral purity, low noise and frequency stability. Thus, each amplifier (63) provides one of the spectral components of the predetermined radar pulse train. The amplifiers (63) are coupled to a multiplexing feed (88, 100) that illuminates a reflector (122). On receive, the multiplexing feed (88, 100) separates the spectral components of the incoming pulse train. Each spectral component is coupled to its own narrow band receiver (131), and one receiver is used to amplify and detect each spectral component. The signals from the receivers (131) are coherently combined in a signal processor (132) in which the signals add coherently and the noise signals do not. The output of the signal processor (132) may be applied to a radar display (133). 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 (80) may be frequency modulated by a modulator (145) to provide communications. It may also be used as a covert IFF system to identify friendly aircraft using IFF code generator (147). 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, using adaptive scanning circuitry (149). It is hard to jam because the receiver array is in sensitive to noise at frequencies out side the narrow bandwidths of the individual receivers and also to noise which is not coherent across the multiplicity of receiver channels. <IMAGE></p> |
