Friday, April 28, 2017

Antenna Gain. Post #1115.

Antenna Gain
(http://www.eham.net/articles/38645).
Author:  Robin Cross (W0FEN).
Accessed on 29 April 2017, 04:55 hrs, UTC.
Please click link to read the full article.

Comment:

A simple, excellently phrased tutorial on Antenna Gain/Antenna Directionality for VHF/UHF by broadcast engineer Robin Cross (W0FEN).

Robin discusses the pros and cons of having "gain" antennas for VHF/UHF mobile work.  Robin says there are times when a simple 1/4 wavelength whip will produce more contacts than the 5/8 wavelength "gain" antennas being touted in the media.  He cites several examples where a shorter antenna will often prove more satisfactory than a higher gain mobile antenna.

Robin says you can use a simple test to determine if a "gain" antenna is necessary for your mobile operation:

To visualize this, hold your hand out with the first two fingers in a V shape. Your fingers should be above and below horizontal. As you rotate your hand vertically, the limits of the main lobe of the antenna will move up and down. You signal will drop out of the repeater and then reappear. So sometimes more ‘gain’ is not better.
As I said at the beginning, an antenna cannot have gain. To have gain it would need a source of power. Amplifiers have gain; antennas do not."

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Aloha es 73 de Russ (KH6JRM).