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I'd like to build this antenna (modified cubical quad), but am sort of confused, because in the original writeup (www.thefsb.org/misc.html), two versions are illustrated. Version 1 is the diagram on the web page, and version 2 is shown in the click-up rotating 3D display. I've sketched both versions and posted them on my website at http://home.att.net/~dmva/wsb/html/view.cgi-photos.html-.html.
Can one of you antenna experts tell me which is the correct version? They aren't identical, although both use the same total length of wire. Are they equivalent, despite appearances?
Also - cubical quad antennas normally use a reflector - none is mentioned in the article. Was that a mistake, or is this one intended to be used without a reflector? I believe this would make the antenna more efficient, and much more directive, right?
Dale
Follow Ups:
I compehend from the original article that the 3-D animation is included simply because the 2-D drawing is not so visually clear. IOW there are not 2 antenna versions, just 2 drawing attempts (BTW, your 2-D representation is better than the visually-challenged author's 2-D attempt). Use the 2-D drawing for dimensional application & the 3-D for actual construction. The last paragraph of the text explains that the Modification (vs a normal Cubical Quad) is to the feed that permits 3dB gain when receiving circular-polarized signals, so that would explain why no reflector was included in this very simple project & why text instruction was given to trial various alignments of the antenna to the station direction. As to wire guage to use for the antenna proper, use any normal insulated hook-up wire not to exceed ordinary lampcord in size. A local RadioShack or Hardware store are sources for the wire & 300-ohm TV twin-lead.
dimensonally, depending if you wish to center tune to the lower FM band, or if you wish to 'broadband' the arrangement. Great, if you have 2 antenna inputs, like Dynalab owners.The use of 300ohm twinlead is, IMNSOHO, archaic; unless you're into vintage stuff. Seems like attaching a balun at the feedpoints is the way to go.
Regardless of the cut frequency, the manner of construction remains an outer loop with an adjacent inner loop of continuous wire. The 3dB gain is achieved via the 300-ohm feed, hardly seems worthwhile to reduce that.
ee right version is forssell.karlsson@telia.com
Ron,
Thanks, I had a hunch that would be the case, Version #2 is it, makes more sense. Addition of a reflector couldn't hurt, though, and might improve performance. I'll do a little experimentation along those lines, probably after Christmas. Kind of hectic now, haven't even started decorating or getting presents for my 7 grandkids, etc. I'll let you know how it comes out. Merry Christmas.
Dale Meyn.
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