Abstract :
A description is given of measurements made to compare the propagation of v.h.f. signals over paths in Cardigan Bay and the Irish Sea, some of which involve transmission over high mountain ridges. Comparisons are made, based on simple knife-edge diffraction theory used together with published propagation data, between the expected and measured field strengths at various distances beyond the Isle of Man mountain ridge. The results of the second series of experiments are applied to confirm that interference between co-channel television stations at Winter Hill, Lancashire and Black Mountain, Belfast should be at an acceptable level.
