The International Telecommunication Union (ITU) has classifications for several frequency wavelengths; this article is considered with explaining two frequency ranges that account for a majority of the communications devices we humans use on a daily basis, either in our daily lives or in the work of certain career fields. And to start off this discussion, we’ll begin with defining them.
- UHF, short for Ultra High Frequency, is the ITU name applied to radio frequencies between the ranges of 300 MHz to 3 GHz*. UHF is also known as the decimeter band as it ranges between frequencies of 1 meter to 1 decimeter.
- The IEEE, short for Institute of Electrical and Electronics Engineers, designates UHF as wavelengths ranging between 300 MHz and 1 GHz. Furthermore, while its designation of L band is used to denote frequencies between 1 and 2 GHz, its S band designation is applied to frequencies between 2 and 4 GHz; the ITU classifies any frequency above 3 GHz as “SHF.”
- VHF, short for Very High Frequency, is the name applied to radio frequencies between the ranges of 30 MHz to 300 MHz.
Applications and Common Usage of VHF
VHF is commonly used in:
- FM radio broadcasts.
- Radio-controlled vehicles.
- Two-way communication devices employed by the private and military sectors.
- Long range data communication via radio modem.
- Marine communications. To clarify, this refers to maritime communications systems and not just the United States Marine Corps.
- Vehicular comms systems, like the CB radio systems used by truckers.
- The communications systems used by air traffic controllers to prevent mid-air collisions between aircraft. This also applies to the system used by pilots to make an informed decision on when and how to land in less than ideal conditions.
- Professional-tier wireless microphones.
- Amateur or “ham” radio.
Applications and Common Usage of UHF
UHF is commonly used in:
- Cellular communications and cordless telephones.
- Satellite-based endeavors like Global Positioning Satellites.
- Wireless and Bluetooth connection to the internet.
- Digital radio broadcasts.
How the Frequencies Overlapped on Television
The television is one of the few devices where both UHF and VHF are employed. From 1938 until the digital set-top box transition of the early 2000s, the analog signal of VHF wasthemeans by which people were able to watch programs. With the rise and eventual complete transition to cable television, television channels are now broadcast through UHF signals.
Limitations between the Two
While both of these frequencies are useful in a variety of fields, they are not without limit. VHF broadcasts are limited to no more than 100 miles along the radio horizon and UHF signals attenuate, or degrade, far more acutely than VHF signals, when passing through heavy rain or storms. UHF signals are also greatly impeded when they do not have line of sight to their source. These problems with UHF transmissions are especially common issues for people who receive their cable via some sort of satellite dish.