Troposferische voortplanting van VHF- en UHF-radiogolven ver voorbij de horizon en enkele praktische toepassingen

This paper deals with the well-known topic: Long distance tropospheric forward scatter transmission. In the introduction the reader is made familiar with some of the conceptions of the forward scatter principle. By using
large transmitter powers, high-gain antennas and extremely low noise receivers it has been possible to establish reliable communication systems bridging distances of 400 kms or more in one hop. The Booker and Gordon theory relating to the mechanism of propagation is clearly represented. Among the other theories of Carroll, Feinstein, the frequency dependent scatter model of Villars-Weisskopf seems to provide the best fit to the experimental measurements. After a short historical review in chapter 2, in which particularly is referred to the early work of Marconi, chapter 3 contains a short indication of the recent extensive research executed in the United States.
Chapter 4 is mainly devoted to the research on troposheric longdistance propagation carried out by the Laboratoty of Physics, Netherlands National Defence Research Council, since 1950. The propagation measurements extending over a range of 20-600 kms in different directions over Western Europe were performed with the kind co-operation of the Dutch P.T.T. and the help of a number of Belgian, Dutch, English, French and German radio amateurs. The condensed result of these investigations is shown in fìg. 5 which is a plot of the median path-loss (expressed in dB below the free-space loss) versus distance. ln this chapter also the problems and phenomena concerning fading, diversity reception, antenna height and degradation of antenna-gain are being dealt with. Chapter 5 is devoted to the practical application of forward scatter etc..