Frequency, power and modulation for a long-range radio navigation system
14 June 1946
The transmission frequency or range of frequencies most suitable for the system is considered. Reception must be assured within a radius of 1500 miles from each ground transmitting station regardless of hour, season, weather, or location, to enable the navigator always to determine his geographical position. The h.f. and l.f. bands are discussed, the latter being analysed in detail. A study of experimental data and consideration of signal and static strengths and fluctuations, and aerial efficiency, indicates that, for a max. distance of 1500 miles, assured reception can be obtained with min. power input at a transmission frequency of ~70 kc/s. Power requirements for several locations are estimated, and the sizes of aerials for handling such power without corona are discussed.