Design of Communication Receivers for the Naval Service with Particular Consideration to the Very-High-Frequency and Ultra-High-Frequency Ranges

This paper points out some of the unusual requirements of naval shipborne receivers which result from their operation on antennas which are necessarily placed in close proximity to numerous transmitting antennas, and the further requirement that numerous receivers must, in some cases, operate from the same physical antenna. In many cases, the entire shipboard antenna system for both transmitters and receivers may be considered electrically as a single antenna with various degrees of coupling between its several parts. This condition places severe requirements on preselector design if cross modulation, spurious responses, and first-oscillator radiation are to be minimized or avoided. At the beginning of the war, the Navy´s standard receivers, covering up to about 30 megacycles, incorporated designs that were quite acceptable in these respects. Little progress, however, had been made in the provision of receiving equipment possessing these characteristics for the higher frequencies. The development described in this paper resulted in models which were closely copied in production and gave comparable performance in the very-high-frequency range to that realized at the lower frequencies. It also provided a design which is adaptable to a wide range of frequency coverage by the simple expedient of providing preselectors for the desired ranges together with change of intermediate-frequency transformers as may be required for specific applications. The sectionalized construction makes this a possible field alteration.