I've been looking at a hex-beam ever since I saw EI7BA John Tait's post on the Internet, so last week I built a 17m version myself. Note that the hex-beam looks like two W's, one inverted over the other. One W (actually, two V's) is the driven element, while the other W is the reflector. (Please see John's notes and pix at http://www.iol.ie/~bravo/ahexbeam.htm before continuing.) In John's "rough drawing" where the insulators attach, I'll refer to those poles as the left and right spreaders, the ends of the driven elements as driven ends, and the ends of the reflectors as reflector ends; where the "V" of the two inverted V's attach, as the upper spreaders; and where the "V" of the reflector V's attach, as the lower spreaders. I bought six, skinny, 8-ft bamboo poles from a local import store, cut a 2-ft disk from heavy plywood, and dug out some 1/2-inch conduit clamps, #22 enameled magnet wire, and the Universal Adapter (duct tape) from the junk box. (All "attaching" of wire to poles was done with duct tape.) I attached the poles to the wooden disk with the clamps, much like John did with his fiberglass spreaders. I then cut the driven and reflector elements according to the formulas that John sent me (do NOT use the "520/F" that John mentions in his notes; instead, see below.) I cut the driven element in half so it could be attached to the bared core and shield of the coax, and I marked the center of the reflector element with tape. (More about this mark later.) I made sure I added extra inches to each length so my three finished elements - both halves of the driven element and the reflector - had a convenient wire loop at all ends, but still had a finished length according to the calculations. The formulas are: - Driven Element = 6180/F; - Reflector = 6262/F; - Tip Space (Driven Element) = 102/F; - Tip Space (Reflector) = 65/F; - Overall Tip Space = 145/F; ALL ANSWERS IN INCHES! The "tip space" mentioned above is the insulating gap between the driven ends (or reflector ends) and the tips of the left and right spreaders. To do this, I attached nylon string to the tip of each left and right spreader, and made loops on both ends of each string such that each string-with-loop formed an insulator whose length matched the tip space as indicated. (I could have made plastic spacers, but the string was handy.) In my case (for 17m) this was about 5-5/8 inches from the left or right spreader tip to the end of the loop for each driven end; and about 3-1/2 inches from the left or right spreader tip to the end of the loop for each reflector end. Next, I ran some 50-ohm coax up through (and attached it at) the hole in the disk, and attached the bared core and shield to the driven element feedpoints. Then, I connected the driven ends and reflector ends to their respective string "insulators" at the left and right spreader tips by un-doing the end wire loops, threading the wires through the insulator loops, and re-forming the wire loops. I also attached the middle of the reflector element (at the mark mentioned earlier) near the disk hole behind the feedpoint. Attaching the feedpoints and element ends makes the last step easy. With the wire ends (and reflector midpoint) properly attached at feedpoint and spreader tip, I pulled the left driven element up the left upper spreader until it formed an inverted "V" and began to flex the left spreader tip, and attached it to its spreader at that point. I did the same to the right driven element, and to the left and right "V" of the reflector element. To tighten the whole arrangement, I stretched nylon string between the upper spreaders to draw the driven elements straighter, and between the lower spreaders for the reflector element. VOILA! - the antenna was complete. I drew a big red arrow on the bottom of the disk for direction of radiation, and attached it with some pipe clamps & metal brackets to a 20-ft pole at the side of the shack. It turns easily by the "armstrong" method. I didn't bother with testing and pruning it, but tuned the antenna tuner for low SWR. I pointed it slightly N of East from my QTH in Boise Idaho, and answered a phone CQ by K0SRI with 100W from my Icom 730. She said I was "coming in like 'Gang Busters', 10-over-9" to Minnesota and to "keep it up". (BTW, this was my second YL contact - X or otherwise - since becoming a Novice in 1969, and my first ever on SSB. Thanks, Maryann!) Since I've never used a beam before, I didn't know what to expect; but it sure seems amazing that something this small and simple acts the way it does. Here's hoping you have as much luck! 73 … AC7UL
Thanks for your article. I saw the production version of this antenna at the Boxboro, MA hamfest. I was looking for some plans to try this antenna out, so thanks for the timely info. 73 de KB1FLR
I'm also interested in trying a homebrew "Hexbeam" and I've also looked at EI7BA's version. Any chance of seeing some photos of your version? Close ups showing construction details would be nice (for us old f**ts who have difficulty following written instructions) Rich K2CPE
more x beam. see 73 amateur today febuary 1998. page 21. it has dimensions for 10 thur 20 meter. it used 10 foot lengths of 1/2 inch residential copper water pipe with 14 gauge stranded copper wire. ed vanoverloop wa2ugt wrote this. see you steve. wb4vte @aol.com.
Does anyone have a copy of above mentioned issue (73 amateur today febuary 1998. page 21.) that they could photocopy and mail to me? I'm willing pay reasonable copying fee and postage. Email reply direct to : rckchp@comcast.net Thanks.
WB4VTE: an 'x beam' similar to the one you mention is also covered in the '92 ARRL Handbook (page 33-15); and Mr. Cebik covers them pretty well at his extensive and knowledgeable site here. However, my experiment was with a hex beam, a different kind of animal. Please see John Tait's site mentioned in the original post, and you'll realize it looks (and acts) differently. AC7UL
@Rich I can mail you zipped fotos of my first installations with lots of details or even a powerpoint file with fotos and details to build a 5 band version (20-10m). But each of the 2 files has about 800 kB. Send me an mail to holger@9h3m.com Holger
Hi: Interesting comments about the similarity of the M-beam and the Traffie Hexbeam. The Traffie Hex-Beam has 60 deg angles while the M-beam, etc. don't. It makes a difference. Mike states that he came up with the configuration on his own. If anyone knows where a Traffie-like "hex-beam" is documented that preceeds Traffie, please send me a reference. Tnx and 73, Tom, NØYD
The Raibeam has a good F/B dip in the rear but only over a narrow range of frequency. I suggest a variable Xc in the center of the reflector like about 250 uufd connected to a selsyn on the mast. You have to make the reflector a bit longer. This will allow you to tune the F/B dip all over the band--or for max gain. The Rr of the Hex beam is around 32 ohms. I suggest a 1/4 wave stub of a 75&92 ohm coax parallel for a 41 ohm stub to match it. I'd add toroids to prevent RF spill over down the coax shield. I have a matching sytem I developed for the Hex beam. It has like all 2 element beams a broad vertical pattern that makes it ideal for low heights and there is a reason for it. It will work higher also. It doesn't require the tower strength etc that the bigger berms do. Many self supporting towers will work for it. It lends itself for stacking and the optimum spacing is around 1/2 wave. I can see no reason to build one as you can't really improve it. It will costs you more $$$ and time to do so. Just buy and install it. One person and do it all by themselves--I can. Big cranes are needed for the rest. I'd like to stack 2-40m beams. I have a switching harness for a coax switch (equal length feedlines to each beam) that allows me to select either beam or both for 3 different angles of radiation and retain 1:1 SWR and more bandwidth for both. It's good beam that serves a nitch about 40' high and will do a great job for it's simplicity. It needs a matching system however. k7gco
I spent quite a bit of time toying with the hexbeam a couple of years back. I found out a couple of interesting things of interest to the homebrewer. The close spaced geometry and the loading effect of the shape, make exact measurements more critical(if building to some formula). Very small changes in the geometry of the hex can cause the resonant frequency to shift. This is MUCH more pronounced than with an ordinary 2 element Yagi(with reference to element spacing). Cebik comments on this to some extent, but I found it difficult to easily reproduce an antenna based solely on the length of the elements. The geometry and element spacing are also critical. If a homebrewer wants to build this antenna from Cebik's design, you might need to use EZNEC to get all dimensions, then make sure the element to element, wingtip to wingtip, and all angles are as near to the model as possible. This is an interesting job too. After you actually build one, you can have fun moving the resonant frequency by varying the angles within the hex(keeping tip spacings and wire lengths fixed). This will also certainly move the gain and f/b ratio characteristics as well. My comparisons on receive showed this to be the case. I used this as an easier method of tuning a monoband hex. By pulling the "side" tips of the hex support structure up a bit, or letting them down a bit, you can vary the angles between the wires. This allows you to fine tune the low SWR point for a decent match(in my case somewher around 30 ohms) without triming the wire. This is more fun to do with a real antenna than the computer model. I spent quite a bit of time figuring this out, as I was fiddling with it before Cebik wrote up his piece, and before I bought EZNEC. Also, I'd suggest someone start with a monoband version first. There are just too many variables with multiband versions, but you can also make it work that way. If you like experimenting, it is a barrel of monkeys. If you get frustrated easily.....buy one.....or consider a yagi. 73 W4KAZ
Another point to consider is when trying to duplicate this beam is this. There is a greater degree of and a critical coupling between the tips of the reflector and DE. This requires a a more critical adjustment of lengths and tip spacings. The F/B dip may very well not be where you want it. Your ability to make the proper measurements and adjustments may be limited. I can do it but as I suggested in my previous post, adding a series variable Xc in the center of the reflector near the mast driven by a selsyn on the mast is a very simple solution. You have to make the reflector a bit longer using the series Xc. You can tune the F/B dip or for max gain anywhere in the band. Only one commercial beam has this feature now done another way. I still say it will cost you many times more of $$$ and time to try and build it yourself and you may never get it right. Buy it and have it up in one day all by yourself. k7gco
