'Some examples of post World War II radar in the USA', by E. King Stodola; in 'Radar Developments to 1945',  Edited by Russell Burns,  Published by Peter Peregrinus Ltd., London, United Kingdom,  on behalf of the Institution of Electrical Engineers.  1988 Pages 478 - 492 Web Sections... Section 1 - Detection of moving target in clutter (478-482) Section 2 - First Radar Detection of the Moon (482-485) Section 3 - VERLORT/PRELORT Satellite Tracking Radars (485-491) Section 4 - Bibliography (492) Used with Permission

       With the end of World War II, applications of radar to space exploration and utilization produced many new developments. One of the most spectacular of these was the world's first achievement of radar detection of the moon by the US Army's Evans Signal Laboratory in early 1946. The background of our Evans Laboratory group in precision frequency stabilization and signal processing in the coherent pulse Doppler system, along with a strong laboratory support system, made it possible to successfully meet this challenge.
       The moon had long been considered as a radar target and could clearly be detected with pulse energies which were large, but not beyond available capabilities. As World War II ended, we considered the possibilities of moon radar detection. The laboratory director at Evans Signal Laboratory Lt. Col. J.H.Dewitt, an ex-engineer from the radio broadcasting industry, had several years earlier attempted tire feat, but without success because of insufficiencies in various elements of his experiment (which he clearly recognised at the time).
       We reconsidered the problem in the light of the resources we had or could easily assemble at Evans Laboratory and concluded that we could work along the lines of conventional radar but with constants greatly re-scaled to handle a 3520km diameter target at a range of about 384000km and moving rapidly with respect to the earth's surface. These figures led to some of the following radar constants: p.r.f. 0.33Hz; pulse width 250000us;receiver bandwidth 10-50Hz. Doppler effect from relative target motion was in excess of the desired receiver bandwidth, necessitating controlled offsetting of receiver and transmitter frequencies. Earlier work on moving target detection had developed both the capability and much equipment to provide the necessary precision frequency management; still earlier work on the Army's

SCR-270/271 search radars had evolved high pulse energy and effective antenna array capabilities which could be gathered together to produce a set which could theoretically perform the feat with an encouraging decibel margin.
       The system was rapidly assembled as planned, (see Figs. 37.7., 37.8., 37.9. and 37.10.), and successfully demon-strated [10] .

       Fig.37.7 shows the block diagram of the moon radar. A bandwidth of 50Hz was selected rather than an optimum figure of under lOHz; the slight loss of visibility was balanced by less stringent tuning requirements and possible additional frequency shift or spreading resulting from the libration of the moon. It should be noted that a portion of the receiver was obtained from an experimental f.m. radar set which had been built for the Army Signal Corps by Major Armstrong. (The f.m. radar was similar in principle to aircraft radio altimeters using sawtooth frequency modulation.)
 

Fig. 37.9 Moon radar apparatus room with  oscilloscope in wooden box

Fig. 37.10 SCR-271 radar transmitter  oscillator neutralised for use  as high power amplifier

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