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Directional Antennas
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by VE3RCN on November 2, 2004
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So its time to think about building a beam...but why always one reflector and multiple directors? Before I try it for fun, any input on an antenna with 2 directors and 2 reflector...or even 1 director and 3 reflectors? Maybe I have just too much time on my hands to think of stuff like this!
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RE: Directional Antennas
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by K8GU on November 3, 2004
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The use of multiple reflectors is quite uncommon. This topic was discussed briefly on the TowerTalk reflector. This post pretty much explains how a Yagi works in plain language:
http://lists.contesting.com/archives//html/Towertalk/2001-02/msg00034.html
Most introductory antenna engineering texts have a similar discussion should you wish to delve deeper.
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RE: Directional Antennas
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by VE3RCN on November 12, 2004
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Thanks. Also, someone at the local club compared it to a telescope...in that you have one mirror and many lenses. I guess is doesnt hurt to think outside of the box and ask a question! 73, Kevin
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RE: Directional Antennas
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by K8DO on November 22, 2004
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Two reflectors mounted one behind the other, will be a waste of one reflector.. The closest reflector will have enough leading phase angle to pretty much shield the second reflector from significant coupling...
If the two, or more, reflectors are in broadside, then they can be tuned properly and will work... I suspect that the 'advantage' will be a few percent at best, to a large negative number at worst...
I had a 4 element 160 vertical array that consisted of a driven element and three reflectors, with elevated radials... It took a bit of time with Elnec to design it, and then lots of time to actually tune it up and get it to play... It did play enough to work VK0 - Heard Island, on 160 without needing to use a receiving beverage, and this was from mid Michigan area...
Denny - K8DO
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