4. What Frequency?
Wireless mics operate within a specific band of radio frequencies which varies from country to country. This is to avoid interference with other devices which have different bands of the spectrum set aside for them, for instance television and radio networks, mobile phones and WiFi routers. Depending on the frequency bands they use, wireless systems are classified as either VHF (Very High Frequency) or UHF (Ultra High Frequency). UHF systems have higher output transmission power and so are less susceptible to interference they can also carry higher bandwidth audio signals than VHF.
Any wireless system must conform to government regulations. As often as not, this will be a problem for the manufacturer to sort out, as the products you buy in any given country will likely conform out of the box. But with more sophisticated multiple wireless systems designed for international use, you may need to apply for a licence. Radio systems designed for sale and use in the UK are available in both VHF and UHF wavebands. Systems in the VHF range 173.800 MHz to 175.000 MHZ and the UHF range 863.100 MHz to 864.900 MHz are free to use, but youll need a license for anything that falls outside these.