I found old plans for a quagi that uses copper for the Reflector and Driven Element and any 1/8" metal available for the directors. The general recommendation for antennas is: no steel for the DE. Is it OK to use for the directors, and OK to 'mix' the metals in an antenna? I'm very new to building and ham in general. I might be able to find something besides steel but so far everything non-steel around here is larger than 1/8".
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$\begingroup$ The DE is probably copper because it is easy to bend and form. 8 AWG wire is close to 1/8", and should be available at most hardware stores. Pull it to make it straight. $\endgroup$– Phil Frost - W8IICommented Oct 12, 2016 at 0:04
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$\begingroup$ The original plans were actually for the 'original' quagi (I guess) but they used #12 copper wire for the REFL and the DE and anything 1/8" for the directors. They worked on this for months (pre-home-computer) so they could have used anything. Why they chose this = unknown. I'm thinking I'll put their numbers in some design program that I need to set up and learn, and tweak from there. I guess I don't have to build this tomorrow. Thanks for the answers/comments. $\endgroup$– Mein TenahCommented Oct 12, 2016 at 6:10
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1 Answer
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It's probably OK to use a different metal for the directors than the driven element, as long as you don't have dissimilar metals touching that would create a galvanic corrosion problem. But steel is a lousy conductor that would make your antenna less efficient. If you wanted to know exactly how much less efficient, then you could model the antenna in EZNEC or 4nec2 to find out.
If you're just making an antenna to better reach the local repeater, and you're not concerned with every decibel, then go ahead and try it! If you're intention is to use the antenna for moonbounce work, in which case you would be concerned with each and every dB, then you're probably better off finding copper, brass, or aluminum rods to use for the directors rather than steel.
My guess would be that the 1/8" diameter recommendation reflects what the antenna designers had on hand; I wouldn't think that a larger diameter would change the specifications of the antenna much. I don't have much experience building VHF/UHF yagis though.
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$\begingroup$ I can get 3/16" aluminum, local and cheap. I am aiming for long(ish) distance simplex use. Thanks! $\endgroup$ Commented Oct 11, 2016 at 20:47
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$\begingroup$ I would use 3/16" aluminum without a second thought. By the way, if you like my answer, please consider accepting it. 73, and have fun building the antenna! $\endgroup$ Commented Oct 12, 2016 at 19:07
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$\begingroup$ I miswrote...I can get 1/4", which I'll still probably use, 'cuz I'm probably going to not stick to the original plan very much. I do appreciate your answer and I did accept it, as far as I know (I'll recheck), but since this is my first question I can accept it but it doesn't show...that's what the little side-box said....until I get X # of somethings; a higher ranking. Thanks for the suggestions! $\endgroup$ Commented Oct 13, 2016 at 3:18