What Are Short Electromagnetic Waves?

A microwave can be defined as a short electromagnetic wave (longer than infrared but shorter than radio waves); used for radar and microwave ovens and for transmitting telephone, facsimile, video and data. The electromagnetic waves having frequencies between and 300 GHz can be called as microwaves. The microwaves are unidirectional in nature. When an antenna transmits microwave waves, the waves can be narrowly focused. This means that sending and the receiving antennas need to be aligned. This unidirectional property of microwaves has an obvious advantage. A pair of antennas can be aligned without interfering with the other pair of aligned antennas.

Microwave propagation is the line of sight. Since the towers with mounted antennas need to be in direct sight of each other, towers that are far apart need to be very tall. The curvature of earth as well as the other blocking obstacles does not allow two short towers to communicate using microwaves. Repeaters are often needed for a long distance communication. Very high frequency microwaves can not penetrate into walls. This characteristic can be the disadvantage if receivers are inside the buildings.  The microwave band is rather wide, almost 299 GHz. Therefore wider sub bands can be assigned, and very high data rate is also possible. The use of the certain portions of the band requires permission from authorities.