Diurnal changes in UHF propagation over the English Channel

Transmissions at 2 GHz over sea paths of 21, 33 and 49 km between the British Channel Islands show enhancements in received signal strength for approximately 6% of the time for the 33 km path and for 9% of the time for the 49 km path. The occurrence of these enhancements peaks in the late afternoon, and is more prevalent during the summer months. This diurnal variation is related to local weather conditions and may be evidence of a sea-breeze/land-breeze oscillation, or changes in air temperature at the sea surface. Whatever the cause, the diurnal variations in signal strength are sufficiently large that it may be appropriate to account for them in system planning.