The Development of a Visual Type of Radio Range Transmitter Having a Universal Application to the Airways

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This paper deals with the development of a visual type of radio range which has universal application to the civil airways of the United States. Following a discussion of the relative merits of the aural and visual systems of course indication, the theory of the production of twelve courses by utilizing a three-phase radio-frequency source is presented, followed by a general description of the transmitter. The necessary requisites of goniometer design are touched upon, and performance curves of the final goniometer illustrate the effect of these factors on the results. The detrimental effects of cross-couplings between the loop antennas are pointed out, and methods given whereby these couplings may be eliminated. Further discussion covers the advantages of neutralization in the transmitter, the relative merits of various types of interstage coupling, and the method used to obtain and determine a three-phase radio-frequency supply. A description of the installation includes a discussion of the characteristics of the loop antennas used for transmission, together with a measured field intensity curve. A course indicator is developed which is useful in aligning and monitoring the courses. Polar space patterns of reed amplitude show the characteristics of the courses obtained with the two-, four-, and twelve-course ranges. The installation is designed to give continuous operation with a minimum number of interruptions due to failure of the apparatus, a condition necessary to the establishment of an aid to air navigation.