A microwave antenna is designed to receive and transmit electromagnetic radiation with wavelengths between infrared (IR) radiation and radio waves. Microwave radiation can travel through the atmosphere or space; the antennas pick up those signals in broadband, a specified band, or single frequency. The technology comes in many sizes and shapes, linking voice and data wireless transmissions for applications such as radar, radio astronomy, and telephone networks.
Microwave antenna applications vary from radio, television, and data communications to radiolocation along the ultra-high frequency (UHF) and military super-high frequency (SHF) bands of the electromagnetic (EM) spectrum. As such, these antennas come in a wide range of shapes and sizes. These can include small helical antennas such as the type found on automobiles, and wireless fidelity (WiFi) antennas for computers and cell phones.
Others are designed in compact lozenge shapes. Larger WiFi antennas are placed on telephone poles and rooftops around cities, universities, and commercial and residential properties in order to transmit data where mobile computing is required. Parabolic dish antennas are high-gain reflectors used to transmit massive amounts of data for media transmission, radio astronomy, and radiolocation (radar).
One type of common microwave antenna is used in cell phones. This mobile communications device transmits in microwave frequencies by radiating energy in every direction. A base station receives the transmission and sends it through relays in a telecommunications network until it reaches its destination. Signals can include data that carry voice, video, and text. Weather effects can influence the performance of the signal, including all types of precipitation, atmospheric conditions, and even physical obstructions that prevent line of sight communication with relay links.
Other factors influencing the utilization of microwave technology include security and casual snooping. Another problem can be channel pollution, that is, commercial competition for limited bandwidths. Additional factors include hardware designs, range, and piggy-backing onto other parties' network subscriptions.
Whatever size or shape of microwave antenna, these powerful transmitters emit radiation in various states of intensity. This includes WiFi and Bluetooth® antennas within networked hot spots often found in public areas. For cell phones, research has shown that these transmission signals are strongest in the initial connecting process, but emit continuously while the phone is powered. Other similar radiating devices include microwave ovens and cordless telephones; these units consistently emit signals. Today's wireless inhabited area continually exposes people to a continuous low field of electromagnetic radiation, with varied degrees of potential health risk.