Abstract :
Soon after the completion of the B.B.C.´s television transmitting station in Devon and the establishment of a full-scale service, complaints were received from coastal areas around Plymouth that the transmission was subject to rhythmic variations in amplitude. The investigations which followed these reports are here described. The variations are found to be due to phase-coherent back-scatter from the sea, and to depend on the configuration of the surface of the sea. The phenomenon is examined theoretically.