RF field intensity meters are used measure the strength of an electromagnetic field. These instruments or receivers are used to detect buried or hidden piping, equipment, and ferromagnetic ores. They are also used to detect cellular phones, remote cameras, audio surveillance or bugging devices, and other products that use radio frequency (RF) transmissions. For example, RF field intensity meters that detect cellular phone transmissions are often used in hospitals, medical centers, military installations, and sensitive manufacturing facilities.
RF field intensity meters can scan a wide range of frequencies. Some handheld models can scan from 50 MHz to 6.0 GHz with varying levels of sensitivity. Others can scan a broader part of the electromagnetic spectrum. Small RF field intensity meters may be equipped with alarms and worn on a person’s belt. Larger devices are suitable for control room facilities.
RF field intensity meters include a category of devices known as very low frequency (VLF) receivers. A VLF receiver detects a radio frequency between 3 and 30 KHz. Submarines use VLF receivers for communication purposes when they are near the surface of the water. VLF radio frequencies are also used for radio navigation beacons and to broadcast time code signals. A VLF receiver can pick up low frequency radio waves that are naturally occurring, such as signals coming from the earth’s magnetic field. These VLF receivers can record these signals and convert them to audio frequencies that sound like chirps or whistles. In this way, research organizations can use a VLF radio receiver to listen to signals from the ionosphere or to record lightning strikes.
Suppliers of RF field intensity meters are located across the United States and around the world. They follow a variety of regulatory requirements and quality standards. In the United States, commercially available devices much conform to guidelines from the Federal Communications Commission (FCC).