Radio frequency bands for wireless mics — VHF (30–300 MHz) is legacy, prone to interference; UHF (300 MHz–3 GHz) is modern standard, stable, dominates professional production.
Wireless microphones only work if the transmitter and receiver operate on the same radio frequency—and this is where the wheat is quickly separated from the chaff. VHF and UHF are the two frequency bands that play a role in film production, and your choice determines reliability, range, and susceptibility to interference on set.
VHF — The Older Standard
VHF operates in the 30 to 300 MHz range and was the standard system for wireless microphones for a long time. The frequencies are stable over distance and penetrate walls relatively reliably—sounds good, but that's the problem. The wavelengths are longer, which is why VHF systems are larger and quickly experience interference in densely populated areas or on sets with many electronic devices. A mobile phone network, an LED light, or the neighboring building's radio mast can destroy the signal. Furthermore, fewer channels are available on VHF today, as many frequency ranges are now reserved for television broadcasting and mobile communications. In Europe and North America, VHF is effectively dead for new applications.
UHF — The Professional Standard
UHF uses the range from 300 MHz to 3 GHz—significantly higher frequencies, shorter wavelengths, more compact hardware. The decisive advantage: there are many more channels available, allowing you to use multiple wireless microphones simultaneously without them interfering with each other. The higher frequency also means better selectivity—sources of interference have less impact. UHF systems are the backbone of modern productions. Whether it's a feature film, documentary, or live event: UHF is the standard. The disadvantage is marginal—the range is slightly shorter with UHF than with VHF, and massive steel structures can weaken the signal. However, on professional sets, you always work with repeaters and well-maintained radio infrastructures.
Practical Use on Set
If you buy or rent a wireless microphone system today, it will be UHF—there is no serious alternative anymore. During soundcheck, you check frequency utilization with a spectrum analyzer to avoid collisions with handheld radios, headphones, or TV stations. UHF systems in the digital standard (2.4 GHz) are even more robust, but also more expensive. You will only find VHF devices in used equipment cases—for nostalgia and historical reconstructions, not for professional productions.