The Effect of the Earth's Curvature on Ground-Wave Propagation

U.S.A. National Committee Report, Fifteenth URSI General Assembly, Munich, September 1966: Commission 2, Radio Propagation in Nonionized Media; Progress in Radio Propagation in Nonionized Media

“…Experimental results obtained by using microwave model techniques have shown good agreement with Wait's formulation, particularly with regard to the nature of waves reflected from coastlines [Maley and O~tesen, 1964;King and Maley, 1965]. Some simplified procedures for obtaining shadow-zone attenuation and height gain at VHF for a homogeneous earth were developed by Burrows [1964] as an e:xten" sion of his earlier work on the subject. The interest· ing effects which result from vertical stratification of the ground have been discussed by Vogler [1964] using previously developed formulas.…”

IEEE Standard Test Procedures for Antennas

“…For each radial set the line marked Òunattenuated Þeld strengthÓ in Fig 67 is extended until it intersects the standard distance (such as 1 kilometer or 1 mile), and the value of Þeld strength is read off. The resulting pattern of unattenuated Þeld strength versus azimuth angle for the standard distance may be used, in conjunction with well-known propagation formulas and published curves [127]Ð [130], to estimate the Þeld strengths at greater distances, where effects such as the curvature of the earth become important.…”

“…Such a pattern is often plotted in terms of contours of equal Þeld strength[103, Section 10. ],[126].When certain conditions exist, a relatively small number of measurements can be used, in conjunction with wellknown propagation formulas and published curves[127]Ð[130], to estimate the Þeld strengths at various other points throughout the coverage area. For antennas operating below approximately 5 MHz the useful component of the ground wave is usually the surface wave because the space-wave component cancels out near the ground [103, Section 10.]…”

The Analysis of Experimental Deployment of IGLUNA 2019 Trans-Ice Longwave System

“…Frequencies used for these transmissions belong to the upper part of the low frequency band (30-300 kHz), designated internationally for longwave (LW) radio broadcasting services. The propagation of these frequencies can be described by many formulas [25][26][27], among which the purely theoretical ones possess significant amounts of inaccuracies and remain barely useful for practical implementations [26]. The solution to these issues is the choice of formulas based on long-lasting experimental research on the RF propagation and reception, which include the natural (and difficult in simulation) characteristics of the terrestrial propagation environment.…”