ii. Microwave

Microwaves are high-frequency radio waves lying roughly between very-high-frequency (infrared) waves and conventional radio waves. Microwaves thus range in length from about 1 mm to 30 cm (about 0.04 to 12 in). They are generated in special electron tubes, such as the klystron and the magnetron, with built-in resonators to control the frequency or by special oscillators or solid-state devices. Microwaves have many applications: in radio and television, radar, meteorology, satellite communications, distance measuring, and research into the properties of matter. Microwave Communications, in short, is a system to use of a high-frequency electromagnetic wave to transmit information. Microwave transmission can be described as microwave radio or microwave telegraphy. It involves receiving and resending microwave signals between relay stations. They are line of sight transmission.