UHF Versus VHF

The idea that UHF wireless systems are inherently better than VHF systems is widespread. But while UHF does offer many advantages, itís not automatically the better choice, especially now as UHF bands become more crowded and remain mired in regulatory uncertainty. There are, in fact, a number of important factors to consider when choosing between UHF and VHF, including where and how a system will be used, the number of systems needed, and, of course, the price.

Despite the common perception, UHF systems do not hold any large technical advantage over otherwise similar VHF systems. However, interference due to electrical equipment, digital devices, computers and other electronic equipment is generally lower at UHF frequencies. This is because noise from these sources becomes less intense as the frequency increases. Also, since VHF wavelengths are longer than their UHF counterparts, enabling them to travel greater distances and pass through obstructions like walls and ceilings, all types of interference will travel farther, and thus be more problematic, at VHF frequencies. But while UHF systems are less likely to suffer interference, cost considerations tend to favor the use of VHF systems.

Still, interference and cost are just two matters to consider. There are also several application issues that can affect the choice between UHF and VHF:

  • Whether the choice is UHF or VHF, diversity systems are highly recommended. Diversity is especially valuable for UHF systems because dropouts due to multipath are more troublesome at UHF frequencies.

  • If the wireless equipment will be used in different cities, VHF systems operating on the special frequencies in the 169-172 MHz range, known as traveling frequencies, will be a good economical choice (applicable in U.S. and Canada).

  • Fixed-frequency (single channel) systems in the TV bands may not be good choices for traveling use. This is because most channels are used in one location or another, and frequency conflicts will eventually occur. Frequency-agile systems will be a better choice.

  • If the wireless equipment will be used in situations where several other wireless systems are likely to be present, UHF systems are recommended. This is because more frequencies are available, reducing the chances of interference.

  • UHF systems are good choices in situations where the smaller and less-visible antennas are highly important, such as when the transmitters must be concealed on the body. UHF may also be preferable if high-performance antennas must be used to extend range.

In summary, there are a great many situations where VHF systems will provide excellent performance at a very affordable price. As such, these are often ideal entry-level systems. But there are other situations where UHF systems are simply the more logical choice. Obviously, not all situations have been covered here and there may be additional factors and complications that must be considered. If you are still unsure of the best choice for your particular application, please contact your dealer or Audio-Technica for further assistance.

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