The signal quality of a wireless microphone directly affects the transmission distance. The signal quality (S/N) is closely related to the transmission power, the distribution of the spatial field strength, the quality of the receiver, the efficiency of the transceiver antenna and the situation of external interference sources.

(1) Receiving and transmitting antennas

The type, length and matching state of the receiving and transmitting antennas directly affect the gain and efficiency of the antenna. Efficient receiving and transmitting antennas use 1/2 wavelength omnidirectional radiating dipole antennas (half-wave dipole antennas). If the length of the antenna is not commensurate with the wavelength, it will directly affect the transmission distance. The wavelength of UHF is short, so the antenna of UHF has a shorter length than the antenna of VHF, and the antenna of the transmitter is more convenient to install.

(2) Interfering signal

The interference signal will increase the output noise of the wireless microphone, and in severe cases, the wireless microphone will not be able to work normally. The sources of interference signals include industrial interference, interference from television and radio signals, adjacent channel interference between multiple wireless microphones, and interference from other radio frequency equipment.

Industrial disturbances: including car ignitions, radios and vacuum cleaners, glow discharge lamps (fluorescent, neon, high pressure mercury). Most of their interference spectrum is in the VHF band.

TV stations, FM radio stations, information and mobile communication stations, etc. have large transmitting power and wide spectrum range, and the interference of VHF frequency band is greater than that of UHF frequency band. The solution is to first figure out the frequency range of these sources of interference, and then choose to use wireless microphone channels that avoid these frequencies.

Adjacent channel interference between multiple wireless microphones: In the use of multiple wireless microphones, adjacent channels are often used at the same time. If the harmonics of one channel fall into another channel, adjacent channel interference will occur. The solution is to choose Use channels with widely spaced frequencies. The number of channels available for the VHF band is not large, and the UHF band has many channels that are widely spaced.