Some models use antenna diversity (two antennas) to prevent nulls from interrupting transmission as the performer moves around. FM modulation is usually used, although some models use digital modulation to prevent unauthorized reception by scanner radio receivers these operate in the 900 MHz, 2.4 GHz or 6 GHz ISM bands. Cheap units use a fixed frequency but most units allow a choice of several frequency channels, in case of interference on a channel or to allow the use of multiple microphones at the same time. Wireless microphones usually use the VHF or UHF frequency bands since they allow the transmitter to use a small unobtrusive antenna. Wireless microphones are widely used in the entertainment industry, television broadcasting, and public speaking to allow public speakers, interviewers, performers, and entertainers to move about freely while using a microphone without requiring a cable attached to the microphone. Most bodypack designs also support a wired instrument connection (e.g., to a guitar). The bodypack is connected by wire to a "lavalier microphone" or "lav" (a small microphone clipped to the user's lapel), a headset or earset microphone, or another wired microphone. In another type the transmitter is contained within a separate unit called a "bodypack", usually clipped to the user's belt or concealed under their clothes. In one type the transmitter is contained within the handheld microphone body. The other audio equipment is connected to the receiver unit by cable. Also known as a radio microphone, it has a small, battery-powered radio transmitter in the microphone body, which transmits the audio signal from the microphone by radio waves to a nearby receiver unit, which recovers the audio.
Singer Cody Simpson using a wireless microphone headset in a 2013 concert in MontrealĪ wireless microphone, or cordless microphone, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated.
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