The Receiving System For Long-Wave Transatlantic Radio Telephony¹

Abstract

Transmission considerations and practical limitations indicate that in the lower frequency range, frequencies near 60 kc are best suited for transatlantic radio‐telephone transmission. A radio receiving location in Maine gives a signal‐to‐noise ratio improvement over a New York location equivalent to increasing the power of the British transmitter about 50 times. Various types of receiving antennas are briefly discussed. The wave‐antenna is selected as being most suitable for long‐wave radio telephony. The various factors affecting wave‐antenna performance and methods for measuring the physical constants of wave‐antennas are discussed in detail. High‐frequency ground conductivities determined from wave‐antenna measurements are given. Combination of several antennas to form arrays is found to be a desirable means of decreasing interference. The use of a wave‐antenna array in Maine decreases the received noise power by an additional 400 times. If the receiving were to be accomplished near New York using a loop antenna, we would have to increase the power of the British transmitting station 20,000 times to obtain the same signal‐to‐noise ratio. Comparisons of calculated and observed directional diagrams of wave‐antennas and wave‐antenna arrays are presented and discussed. The transmission considerations governing the design of a radio receiver for commercial telephone reception are outlined. Mathematical discussions of the wave‐antenna, antenna arrays, quasi‐tilt angle, and probability of simultaneous occurrence of telegraph interference are given in the appendices.