During the cruises all possible data were collected on the detec- 

 tion of ice. The action of all radars on each ice target and on ship 

 targets was carefully noted. The effects of air new developments 

 and ideas were recorded for possible usefulness. After each cruise 

 the data were analyzed so that any new developments could be dis- 

 covered prior to the next experimental trip. 



Type of Radar Used 



It was considered possible that the frequency of the microwave 

 radar used would influence results. The fact had been established 

 that certain frequencies were better suited for some types of work 

 than others. The definition (fidelity of reproduction) properties 

 of the shorter wavelengths are excellent for navigational purposes, 

 but just how these shorter wavelengths would react to ice was not 

 known. The longer wavelengths have a wider antenna beam pat- 

 tern in search radar which reduces the directivity of the set. The 

 effect of the heavy sea in the area of the Grand Banks on radar 

 propagation could only be guessed from results obtained elsewhere. 

 It had been proved that ships could be tracked through very heavy 

 sea conditions without losing the echo in the sea return. Whether 

 or not the same would be true with bergs and growlers was un- 

 known. It was hoped that enough information could be obtained 

 about the factors involved that an intelligent comparison of the 

 relative merits of the various frequencies of the microwave band 

 could be made. 



So that a comparison might be effected the U.S.C.G.C. Mojavc 

 was equipped with both 10 cm. and 3 cm. radars. These two sets 

 were standard Navy small ship models of the two useable micro- 

 wave frequency bands. Just prior to the beginning of the investi- 

 gation in 1945 both radars were completely overhauled by the 

 manufacturer's engineers and placed in the best possible operating 

 condition. Thus present for the investigation were two radars of 

 different microwave bands in top operating condition. The broad 

 antenna beam pattern and poor definition properties of the 10-cm. 

 band could be compared, insofar as ice detection was concerned, 

 with the narrow beam pattern and excellent definition properties 

 of the 3 cm. 



Each radar was equipped with all the latest modifications and 

 installed with sufficient test equipment to allow a quantitative com- 

 parison of the two radars to be made. These test sets were of the 

 signal generator type which made it possible to measure the aver- 

 age power output, frequency and the receiver sensitivity. It was 

 also possible to match any incoming echo with a generated signal 

 of known strength so that at any range to the target the exact sig- 

 nal strength of the returning echo could be measured. Here then 



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