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It is a truism
On 11/14/2014 3:49 PM, Ralph Mowery wrote:
"Jerry Stuckle" wrote in message ... On 11/14/2014 12:34 PM, wrote: You ignore the fact this is an idealized environment. That is NEVER the case in a real installation. I have WAS on 75 SSB (from Iowa) with an inverted Vee. The top was only 50' in the air. And late at night in the wintertime I had pretty solid communications over much of the continental U.S. (back in the late 70's and early 80's). Antennas NEVER work "as predicted" - and anyone who claims they do does not understand antenna operation. Antennas 'always' work as predicted. People just don't always factor in everything in the prediction. Just as I worked a station on 432 MHz with 25 watts to a 1/4 wave ground plane that was about 1000 miles away. Nice bit of tropo that day. The problem is - taking into consideration EVERYTHING which could affect it. Well nigh impossible - even the neighbor's chain link fence could have an effect, for instance. That's why AM commercial radio stations plan their antenna phasing for the desired pattern - but then have to measure it almost always tweak the delay lines to get the exact shape they want. For instance - I remember one I worked at back in the 70's. It's pattern was directly affected by moisture in the air and, to a certain effect, ground. You could see the difference in tuning for the transmitters between a very foggy night and a clear one. This also caused a change in the radiated pattern. Fortunately it was still with the limits set by the FCC, or we'd have to rephase the towers with every change to the weather. BTW - the main cause was the ground plane (circles of wires around each tower with radials from the tower out - and silver soldered where ever the wires crossed) was pretty old, and subject to changing weather conditions. I bet I could put up a g5rv at 30 feet on some rare country and get loads of 5/9 signals no mater how many times the calls had to be repeatd. I highly suspect you could! --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
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