Commemorating 60 years of radio-ralay transmission, this text provides an insight into the history, evolutionary development and technology of radio-relay systems and highlights applications where radio-relay transmission is more effective a solution than satellite or cable networks. The author details the latest technology, helping the reader to understand the performance of radio-relay systems and gain an insight into propagation, the frequency spectrum and its international co-ordination, modulation, radiation and the coexistence of radio-relay and satellite systems.