Distance dependence, fading characteristics and pulse distortion of 3000-MC trans-horizon signals

Statistical analysis of signal recordings at 10 cm wavelength has given the following results. The distance dependence of the half-hour signal medianF_{m}over a sea path corresponds to a scattering parameter which is approximately inversely proportional to the height. BetweenF_{m}and the surface value ofMa correlation coefficient of 0.62 is found, and betweenF_{m}and the dew point 0.55. A unit increase ofMseems to be followed by a signal increase between the limits 0.3 and 0.8 db. The fading range, as defined between the 10 per cent and 90 per cent of time levels, is 12-14 db, and the fading frequency mostly about 2 c/s for a 300 km path. Over a 260 km land path the pulse broadening was normally0.1-0.2 \mus which corresponds to a scattering parameter varying inversely as the first to second power of the height. A severe pulse distortion caused by selective fading is found to be very common. Some other propagation characteristics are also discussed.