. Das Bell System technische Journal . mpedance, between cathodes ^®mittels des Verteilsystems der gleichen Länge koaxiale Leitungen shownin Abb. 11. Dieses Verteilungssystem gibt allen Detektoren äquiphasenschlagende Oszillatoreingänge und macht Anforderung (2) erreichbar, indem es nominale Ähnlichkeit in den übrigen Teilen der sechs Schaltungen hat. Die Anforderung (1) wird durch die Einspeisung eines Testoszillators von 78 Ohm im-Pedanz in die erste Schaltkreisbuchse und die Einstellung des Abstimmkondensators ^^ W. A. Harris, Superheterodyne Frequency Conversion Systems, Proc. I. R. E., VOL 22, S. 279-294, April 1935. EIN MULTIP
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. The Bell System technical journal . mpedance, between cathodes ^®by means of the distributing system of equal length coaxial lines shownin Fig. 11. This distributing system gives equiphase beating oscillatorinputs to all detectors and makes requirement (2) attainable by havingnominal similarity in the remaining parts of the six circuits. Requirement (1) is met by feeding a test oscillator of 78 ohms im-pedance into the first circuit jack and adjusting the tuning condenser ^^ W. A. Harris, Superheterodyne Frequency Conversion Systems, Proc. I. R. E., vol. 22, pp. 279-294, April, 1935. A MULTIPLE UNIT STEERABLE ANTENNA 355 and the coupling condenser (Fig. 10) alternately until the maximumsignal voltage appears on an indicating meter in one of the three inter-mediate-frequency branches. The three-terminal coupling condenseris an aid in this procedure since varying the coupling imposes only aslight variation in the capacitance across the coil. When the indicatinginstrument is a square-law vacuum tube voltmeter with the main. Fig. 11—Close-up view of high-frequency panel with cover removed. The beatingoscillator supplv line originates in the upper right-hand corner. It supplies the sixdetectors withequiphase and equiamplitude voltages. Plug-in coils fit into thecompartments covered by the six circular doors. Micrometer heads which are usedto adjust the six tuning condensers appear. The coaxial patch cords appear at theextreme left. 356 BELL SYSTEM TECHNICAL JOURNAL current balanced out and the remainder indicated by a 30-micro-ampere meter, the sensitivity is more than sufficient to tune the circuitscorrectly. The criterion of correct tune is the degree of suppression of standingwaves on the transmission lines. To determine whether or not themaximizing adjustment insures an adequate standing wave sup-pression, a standing wave detector was incorporated in the experi-mental design. This is shown in Fig. 12. It consists of about 16meters of 78-ohm coaxial line arranged
