. The Bell System technical journal . converter consists of a beating oscillator operating in the microwavefrequency region and a nonlinear element, which at the higher radar fre-quencies consists of a point-contact crystal element. At the lower radar nn lUiLL SYSTEM TECIIMCM. J01R.\AL frequencies it is customary to employ vacuum tube radio-frequency ampli-tlers preceding the converter element, and in these cases, similar vacuumtubes are employed as the nonlinear element. The output frequency of theconverter commonly ranges from 30 mc to 100 mc. Because of the com-parative difficultie
. The Bell System technical journal . converter consists of a beating oscillator operating in the microwavefrequency region and a nonlinear element, which at the higher radar fre-quencies consists of a point-contact crystal element. At the lower radar nn lUiLL SYSTEM TECIIMCM. J01R.\AL frequencies it is customary to employ vacuum tube radio-frequency ampli-tlers preceding the converter element, and in these cases, similar vacuumtubes are employed as the nonlinear element. The output frequency of theconverter commonly ranges from 30 mc to 100 mc. Because of the com-parative difficulties experienced in the transmission of microwave energyover transmission lines or waveguides as contrasted with the problem at thelower intermediate frequency region, it is standard practice to locate theconverter in close proximity to the antenna and transmitter portions of theradar system. The intermediate frequency (IF) amplifier and associated second detectorunit following the converter in Fig. 4 is required to obtain the necessary. Fig. 4.—Schematic diagram of principal C()mi)niuiits ol a military radar recei\-ei amplilication to the wanted signal, to sui)ply discrimination against un-wanted signals, and to finally convert the desired signal to a video form forpresentation purposes. The usual gain required of a modern radar inter-mediate amplifier is of the order of 100 db. The band width of the ll-ami)lirier is usually chosen between 1 mc and 10 mc depending on the specificradar system requirements. The techniques of construction developed forhigh gain radar IF amplifiers have resulted in compact component designswhich are complete units in themselves, caj)al)le of being integrated intovarious radar systems. The video amplifier characteristics are dependent to a large degree onllic parti( iilar type of display system associated with it. Its primary func- THE RADAR RECEIVER 705 tion is to amplify the video signal output of the second detector, togetherwith some other signa
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
