Color and the Spectrum: UHF/VHF
Steve Beeson, Arizona State University

What does UHF and VHF mean?

Good question. UHF stands for ultra-high frequency and VHF means very-high frequency. Considering the very low energies of these waves (10-7eV to 10-5eV) which corresponds to a very low frequency, it's hard to understand why someone called them "ultra-high" and "very-high". UHF and VHF waves are essentially just a-little-higher-energy radio waves. Since their energies are so low (in comparison to the rest of the spectrum) we tend to think of them as waves instead of photons.

Your standard television antenna (the one with the horizontal metal rods, not the satellite dish) receives VHF and UHF waves from the local television stations. The reason for the long rods? Since these waves have wavelengths of a few centimeters to a few meters, the electrons in the metal of the antenna need to be able to vibrate with the same wavelength in order to "pick up" the signal. Bunny ears on your old TV set usually aren't as long as the rods on your roof-top antenna, so your reception probably isn't as good. Plus, the metal in your house tends to block and distort the signal, whereas non-conductors easily pass the waves. Humans, on the other hand, act as a good conductor for many TV waves, thus touching the antenna helps with the reception.

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Copyright &copy1995-1997
Steve Beeson, Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287