. The Bell System technical journal . use the phase shiftersoperate at the intermediate frequency of 396 kilocycles. The phase shifters are connected to the steering shaft with helicalgears of multiple ratios as shown in Fig. 15. The phase shifter shaftsmay be slipped with respect to the main shaft. After they have beenaligned so that locally supplied equiphase inputs to all detectors add inphase at the point where the phase shifter outputs are combined theyare locked. This adjustment is independent of signal is made for adjusting the gain of each of the six phase shifterci
. The Bell System technical journal . use the phase shiftersoperate at the intermediate frequency of 396 kilocycles. The phase shifters are connected to the steering shaft with helicalgears of multiple ratios as shown in Fig. 15. The phase shifter shaftsmay be slipped with respect to the main shaft. After they have beenaligned so that locally supplied equiphase inputs to all detectors add inphase at the point where the phase shifter outputs are combined theyare locked. This adjustment is independent of signal is made for adjusting the gain of each of the six phase shiftercircuits so that the differences in transmission-line loss may be com- A MULTIPLE UNIT STEERABLE ANTENNA 359 pensated and any other desired amplitude adjustments made. Thephotograph of Fig. 15 shows the monitoring or exploring branch whosesteering shaft is motor driven at one revolution per second. Before leaving the subject of phase shifting it may be well to dis-tinguish between phase shift and delay as here used. All electrical net-. Fig. 15—Phase shifting panel of the monitoring branch. Only five of the sixphase shifters are rotated for steering purposes. They are geared to the steeringshaft in ratios of 1 : 1, 1 : 2, 1 : 3, 1 : 4, and 1 : 5. works, except for certain highly distortive ones, possess a phase-fre-quency characteristic which is such that higher frequencies have theirphases retarded with respect to lower frequencies. The ratio of thencrement of phase retardation to the increment of frequency, , the 360 BELL SYSTEM TECHNICAL JOURNAL slope of the phase characteristic, is the delay. It is sometimes calledthe group delay or group transmission time as distinguished from thephase time. ^^ The delay is the only time which can be does not determine the phase shift of a particular frequency nor is itdetermined by the phase shift. A phase shifter applied to the net-work merely moves the phase curve intact up or down on thephase axis. General Description o
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