Ionospheric influences in television reception

A review is given of the circumstances and characteristics of ionospheric reflections of v.h.f. waves, with reference to their effects on television reception. It is shown that sustained v.h.f. propagation via the F2 region may occur for limited periods during a defined phase of the cycle of solar activity, whilst irregular and intermittent ropagation via forms of sporadic ionization in the E region may be experienced during certain months each year. The range of frequencies affected embrace those currently in use for television services in the United Kingdom and elsewhere. A summary is presented of the circumstances under which interference effects to the reception of these services may be expected, owing to the use of common frequencies for remotely-situated short-distance v.h.f. services.