A wireless microphone, as the name implies, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Wireless microphone systems are a key component in almost every broadcast, motion picture, theatrical and sound stage production, as well as corporate, religious and educational venues.
The professional models transmit in VHF or UHF radio frequency and have true diversity reception which eliminates dead spots and the effects caused by the reflection of the radio waves on walls and surfaces in general. The VHF band is located in the frequency range between 30 MHz and 300 MHz. This is the other common band used in wireless microphone systems, but it is not used as commonly as UHF.
VHF wireless microphones are typically those of the fixed frequency type, meaning that the user has no opportunity to switch frequencies if interference is encountered. The UHF band is located in the frequency range between 300 MHz and 3 GHz and is the most common band used in wireless microphone systems. Depending on national regulations, which differ for every country, wireless microphones may operate in the range between 470 MHz and 865 MHz. These frequencies are shared with over-the-air TV broadcasts. So when selecting a frequency, the user must know what frequencies to stay away from to avoid interference.
Advantages and disadvantages of wireless microphonesThe biggest advantage of a wireless microphone system is its freedom of movement. Since a wireless microphone is not connected by any cable, the user does not get restricted by the length of the cable. Wireless microphone sends audio signals over the air, rather than through microphone cables. The microphone is attached to a transmitter and the signals are received by a receiver connected to the audio console or recording device. The user can avoid cable problems which frequently occur because of the constant moving and stressing of the cables.
Though wireless microphones are in use everywhere, they have their disadvantages too, regardless of their state of the art technology. They have only a limited operation time due to low battery life. They do not work if the user takes the microphone out of range. Sometimes there may be the possibility of interference with other radio equipment or other microphones.
Different kinds of wireless microphones
Generally they are two types of wireless systems - handheld wireless systems and bodypack wireless systems.
A handheld wireless microphone is like a normal wireless microphone, but it has a bigger body to accommodate the transmitter and battery pack.
Bodypack microphones are a small box housing the transmitter and battery pack, but not the microphone itself. It is attachable to the belt or elsewhere and has a wire going to headset, lavaliere microphone or a guitar.
Some of the manufacturers of wireless microphones offer a plug on transmitter for existing wired microphones which plugs into the XLR output of the microphone and transmits to the receiver. This offers many of the benefits of an integrated system, and also allows microphone types to be used without a cable.