VHF

144–148 MHz: Ama­teur radio 2 Meters band

Very high fre­quen­cy (VHF) is the ITU-des­ig­nat­ed range of radio fre­quen­cy elec­tro­mag­net­ic waves from 30 MHz to 300 MHz. Fre­quen­cies imme­di­ate­ly below VHF are denot­ed high fre­quen­cy (HF), and the next high­er fre­quen­cies are known as ultra high fre­quen­cy (UHF).

 

These names refer­ring to fre­quen­cy usage orig­i­nate from the ear­ly 20th cen­tu­ry, when reg­u­lar radio ser­vice used the terms LF (low fre­quen­cies), MF (medi­um fre­quen­cies), and HF (high fre­quen­cies). These names were stan­dard­ized by the Inter­na­tion­al Telecom­mu­ni­ca­tions Union (ITU) and extend­ed to high­er fre­quen­cy ranges.

 

Com­mon uses for VHF are FM radio broad­cast­ing, tele­vi­sion broad­cast­ing, land mobile sta­tions (emer­gency, busi­ness, pri­vate use and mil­i­tary), long range data com­mu­ni­ca­tion with radio modems, ama­teur radio, marine com­mu­ni­ca­tions, air traf­fic con­trol com­mu­ni­ca­tions and air nav­i­ga­tion sys­tems

VHF prop­a­ga­tion char­ac­ter­is­tics are ide­al for short-dis­tance ter­res­tri­al com­mu­ni­ca­tion, with a range gen­er­al­ly some­what far­ther than line-of-sight from the trans­mit­ter (see for­mu­la below). Unlike high fre­quen­cies (HF), the ionos­phere does not usu­al­ly reflect VHF waves (called sky­wave prop­a­ga­tion) so trans­mis­sions are restrict­ed to the local radio hori­zon less than 100 miles. VHF is also less affect­ed by atmos­pher­ic noise and inter­fer­ence from elec­tri­cal equip­ment than low­er fre­quen­cies. Whilst it is blocked by land fea­tures such as hills and moun­tains, it is less affect­ed by build­ings and oth­er less sub­stan­tial objects than UHF fre­quen­cies.


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