Wireless microphones are a portable, versatile way to record or broadcast sounds. Without a cable connecting the microphone to a camera, recorder, or speaker, a journalist or performer can act unhampered. Wireless microphones use radio signals to communicate between the transmitter and the receiver.
You have no doubt encountered wireless microphones countless times, whether it was watching an awards show on television, attending a local talent contest, or listening to a professor's lecture. Each of these events requires that a person's voice is amplified or recorded in a way that allows them to walk, dance, point at a map, or otherwise move without the constraint of a cumbersome cord.
The technology of wireless microphones is similar to the mechanisms that make wireless headphones and speakers work. There are three components that work together to create and transmit a signal to where it can be recorded or amplified. The first part is the actual microphone. It can be very tiny and clip around your ear or onto your lapel.
The second part of wireless microphones is the transmitter. This device converts the audio to a signal either in the FM, VHF, or UHF bands of the radio spectrum. The final component, the antennae, broadcasts that signal a short distance, much shorter than the music that comes through your car radio. An antenna is fairly large, so it can be part of a self-contained microphone.
When you want a small wireless piece that clips next to your mouth, you must wear the larger antennae as an external part of the microphone. Since microphones must use short-range radio frequencies, it's subject to different kinds of interference. If you are using it on location, you may experience interference from metal poles, walls that reflect the signal, or other large structures.
Adjusting the band over which you are broadcasting can strengthen the range of the signal. You should be able to avoid anybody else using radio signals in the immediate area by choosing another frequency. The unit runs off ordinary batteries, so weak or scrambled signals can usually be fixed with fresh batteries.