Study Group 5 studies on propagation in non-ionised media

CCIR studies in recent years of the non-ionised medium have been in four main areas. Two of these have been on the radio-science aspects of: (i) the effects of the Earth´s surface and terrain features (e.g. hills, buildings, trees, etc, according to the frequency of interest), and (ii) the effects of the atmosphere (e.g. refractive index changes, precipitation, etc). This paper contains some broad descriptions of the work of Study Group 5, as well as picking out some of the specific areas currently of importance. The author has concentrated on the UK contributions and certain European COST projects, with a view to further developments