Part I of this paper first describes a method of measuring attenuation and field strength in the ultra-short wave range. A résumé of some of the quantitative experiments carried out in the range between 17 mc. (17 meters) and 80 mc. (3.75 m.) and with distances up to 100 km. is then given. Two cases are included: (1) “Optical” paths over sea-water and (2) “Non-optical” paths over level and hilly country. An outstanding result is that the absolute values of the fields measured were always less than the inverse distance value. Over sea-water, the fields decreased as the frequency increased from 34 mc. (8.7 m.) to 80 mc. (3.75 m.) while the opposite trend was found over land. As a rule, the signals received were very steady, but some evidence of slow fading was obtained for certain cases when the attenuation was much greater than that for free space.
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Schelleng et al. (1933) studied this question.