Some Measurements of Height Gain at V.H.F.,
MARCONI RESEARCH CENTRE CHELMSFORD (ENGLAND)
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This paper reviews some of the published work on antenna height gain and highlights limitations of the currently available information. Comparison is then made with the results of height gain experiments undertaken in South East England at frequencies of approximately 95 MHz and 200 MHz. The variation of height gain is investigated, as is a relationship between height gain and the location variability of received field strength within a given environmental area. Experiments performed at about 95 MHz used vertical polarisation and path lengths vary from about 25 km to about 105 km. These paths were predominantly over land and were all obscured. The antenna employed was omnidirectional, and measurements were taken at many locations within each predetermined area at heights above local ground from 7 m to 30 m. Some measurements were also made on sloping ground to give effective heights of up to 60 m. The results are compared with some earlier measurements made at about 200 MHz over similar paths using a directional antenna at heights from 3 m to 10 m above local ground.
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- Radiofrequency Wave Propagation