 - The term microwave refers to electromagnetic energy having a frequency higher than 1 gigahertz (billions of cycles per second), corresponding to wavelength shorter than 30 centimeters.
Microwave signals propagate in straight lines and are affected very little
by the troposphere. They are not refracted or reflected by ionized regions in the
upper atmosphere. Microwave beams do not readily diffract around barriers such as
hills, mountains, and large human-made structures. Some attenuation occurs when
microwave energy passes through trees and frame houses. Radio-frequency (RF) energy
at longer wavelengths is affected to a lesser degree by such obstacles.
The microwave band is well suited for wireless transmission of signals having large bandwidth. This portion of the RF electromagnetic radiation spectrum encompasses many thousands of megahertz. Compare this with the so-called shortwave
band that extends from 3 MHz to 30 MHz, and whose total available bandwidth is only 27
MHz. In communications, a large allowable bandwidth translates into high data speed.
The short wavelengths allow the use of dish antennas having manageable diameters.
These antennas produce high power gain in transmitting applications, and have
excellent sensitivity and directional characteristics for reception of signals.
| LAST UPDATED: |
06 Nov 2006
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