Do I want a hamburger or a chicken sandwich? The biggest question I face when I order at fast food restaurants. Not necessarily fast food, but you may have to choose between VHF and UHF frequencies. In this blog we will explore the differences between VHF and UHF and where it might fit in your operation.
Frequency – Defines the oscillation rate of a radio wave, how fast it goes up and down. This frequency rate is called Hertz.
VHF – Very High Frequencies. Radio waves that oscillate between 30 megahertz (MHz) and 300 megahertz.
UHF – Ultra High Frequencies. Radio waves that oscillate between 300 megahertz (MHz) and 3 gigahertz (GHz).
Going back to the fast food comparison, do I really need a UHF radio when a VHF radio will do just fine? Aside from the definitions, both VHF and UHF have different characteristics.
VHF in Short
VHF radios use line-of-sight to talk with other radios, they generally work better than UHF over long distances. A radio’s output power also affects the transmission range, so naturally a 5W radio can transmit farther than a 2W radio. Generally, if you are within range on a flat ground without any obstruction, you can easily talk to another user as long as the distance is not too great. For example: if you have a radio and your friend is standing 80 feet away from you in an empty field, you can easily talk. However, if there is a mountain or a large building between you and your friend, it might disrupt communications.
But that doesn’t mean that VHF radios cannot operate in buildings or around cities. Plenty of businesses use VHF radios because the worksite or operation isn’t huge. Or the buildings aren’t large enough to lose connection.
Marine radios use only VHF radios due to the environment in which they are used. Since they are designed to be used in open waters, most of the time there are minimal obstructions. The same working environment applies to aircraft and open skies.
UHF in Short
UHF radios also use line-of-sight communications. However, UHF signals are higher in the frequency spectrum. This means that the frequencies can more easily work in building structures and other obstacles. Hospitals, large education campuses, parking garages benefit from UHF’s shorter wavelength. Radio waves are determined by wavelength, the longer the wave the farther it travels. UHF radio’s wavelengths are shorter but they do penetrate objects much better than VHF.
Typically, you would find UHF radios in more indoor applications, but that’s not to say they don’t work perfectly fine outside either. They can serve as an alternative frequency band for businesses if the frequency spectrum licenses are filled.
Weather
As amateur radio enthusiasts know, the weather plays a factor in radio transmissions. You can still use radios in any weather, just expect ranges to be shorter when the weather is inclement.
For example, when it rains, each rain droplet takes up space, the radio waves must pass through the drops. The rain may absorb or scatter the radio wave, thus weakening the signal. This is also known as attenuation, when the wavelength energy is diffused.
Which Should I Choose?
Your choice depends on how you expect to use the radio. Here are a couple of examples to help drive your decision.
Indoors: If you work in a smaller space, less than 250,000 square feet or so without plenty of thick concrete walls such as retail stores or restaurants. Either frequency band would work, but UHF would be best for areas with lots of corridors and sectioned off areas such as parking garages.
Outdoors: With VHF radios, they work well over long ranges outdoors. Open construction sites, road crews, transportation, or outdoor events. UHF radios work just as fine outdoors, however with the shorter wavelength, the overall range for long distance communications is not ideal.
