Gain degradation of a 25 m paraboloidal aerial on 2 GHz transhorizon radio paths

The apparent loss of gain referred to as `gain degradation¿, or `aperture-medium coupling loss¿, is normally severe on high-gain aerials when used on tropospheric scatter (beyond line-of-sight) radio paths. The paper reports measurements made using a 25 m-diameter paraboloidal aerial on two 300 km troposcatter radio paths at 2 GHz, compares these with data previously published, and emphasises that this gain degradation may increase significantly for small time percentages.