Daily Facts
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VHF Radiation Above the Horizon

October 7th Fact-of-the-Day

Most VHF communication utilizes direct waves rather than sky waves. Half the transmitted power will be radiated into the sky and wasted (aircraft communication is an exception) if a high VHF antenna is aimed at the horizon when using direct waves. Antennas that are directional both vertically and in azimuth can be tipped down toward the earth slightly to aim the main vertical beam at the earth where radiation can be received. The phases of radiators stacked vertically can be properly chosen to tilt the main vertical lobe of radiation from omnidirectional antennas down toward the earth. ©2004 Martek International All rights reserved.


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