ABSTRACT
To appreciate the impact of communications using RF waves, one has only to recall that before 1895, the British Admiralty, employing the best available technology, communicated with its fleet in the English Channel by using telescopes, flags, and
flashing lights. This visual communication system functioned over that limited range as long as the weather was clear, but it was defeated by fog, which unfortunately was a common occurrence in the English Channel. Contrast that with the situation a century later when RF waves traveling through space without wires or cables carry voice, data, and picture messages between points on Earth separated by thousands of miles in any type of weather and even carry commands from Earth to spacecraft at the outer edges of the solar system.
