For amateur radio operators, the quest for the perfect antenna never seems to end. Perhaps that’s because our requirements are always changing. We never quite seem to get to one design that can do everything. This copper-foil Yagi antenna might not do everything, but it really seems to tick off the boxes for gain and directionality along with ultra-portability.
If you’ve been following [Ben Eadie (VE6SFX)]’s trip down the rabbit hole of lightweight antenna building, you’ll recall that he’s already knocked off a J-pole antenna and a stealthy mobile slot antenna using little more than copper foil tape. Both of those designs performed great, but [Ben] had bigger fish to fry: he wanted to build a directional antenna for the 2-meter band and go for distance. The traditional Yagi-Uda is generally the preferred design for beam antennas, but they tend to be bulky and cumbersome. But with a roll of copper foil tape [Ben] was able to lay out a three-element Yagi on a sheet of Tyvek wrap. Reinforced with some packing tape and stiffened with a couple of fiberglass rods attached to a 3D printed handle, and it was ready to go.
[Ben]’s field test results were most impressive. Not only was he able to open up repeaters up to 90 km away, but he was getting good signal reports to boot. He was even able to reach a repeater 150 km distant, just barely though. Still, that’s mighty impressive performance from something that looks like a Union Jack and rolls up to fit in a pocket.
I was imagining something that unfurls like an umbrella. I guess that’d be the next generation of the concept. Cool work, just not quite as cool as I thought at first.
I like your umbrella idea! “Golf” umbrellas can get pretty big. Makes me wonder how much a yagi’s gain and/or directionality degrade if the elements are curved (i.e. when the yagi element pattern is projected onto a sphere, with the umbrella’s handle acting as a mast). Someone should try this, or at at the very least run this geometry through a simulator. Hmm, there is the matter of those pesky metal “ribs.” Carbon-fiber composite anyone?
Umbrellas are curved because that is a good shape for stopping rain, there is no reason an umbrella like mechanism can’t produce a flat surface instead.
Yes, true. But umbrellas, even large quiet ones, can be bought off the shelf, and fold nicely into a portable package. A compromise is to fashion a stretched-planar “floor” under the curved dome.
My technical question is more straightforward than I originally thought: do yagis have to be planar to preserve their famous properties of high directionality and gain?
Instead of an umbrella how about one of those windshield type umbrella ; the windshield screen that opens up like an umbrella is rectangular and flat
PERHAPS a reversible Golf Antenna with a possible Signal booster combined… For Distance!
I really don’t see the advantage of the tape. A 2m Yagi with threaded elements that screw to the boom is extremely portable and can be set up in a couple of minutes. It would have far less wind resistance and could have more than three elements. I guess cheap is the biggest advantage of the tape approach, but otherwise it isn’t the most practical … and he already has to use fiberglass rods to support it. Those rods could have been the elements.
It might simply be because it is super easy to experiment with.
Not really. I’s FAR easier to model wires or tubes than tape. At 146 MHz, wires and tubes mounted on 3D printed sliders can be moved along a boom to change spacing MUCH easier than lifting tape and hoping it sticks again in the new position. Wires and tubes hold their position while you’re doing the testing, versus the floppy pillow case shown in the article.
I’ve never understood the advantage of a “pocketable antenna” in the first place. None of the other gear that the user would bring along fits in a pocket so they’re going to be carrying a bag or backpack anyway. Having something relatively bulky in your pocket (compared to things that usually go in your pocket) just makes things needlessly awkward.
I’m sure it’s fun to experiment with tape antennas and that’s great, but pretending they actually have an advantage seems like a big stretch to me. And no, they don’t have a significant bandwidth advantage. The tape is oriented wrong for that.
At scale, there are things like https://www.cubic.com/inflatable-satellite-antenna
Well for those of us in Search and Rescue having a HT and a pocket Yagi is a huge advantage. strapping the poles to my pack is easy. The foil is more manipulative than any wire I know of and with the width it is the equivalent 1/4″ diameter copper tube given the skin effect. Anyhow this is obviously not your thing and that is cool. But don’t dismiss something so quickly. There is some great learning to be had on these antennas using foil
I built a 7 element 2M yagi with a 2 section boom and the elements gets assembled in place with elastic bands or zip ties as retainers, much easier on sota days than lugging a 7 element up a mountain😂
Hi,
Could you drop me the 3D print file?
You can find it here for free on this Patreon post https://www.patreon.com/posts/ultra-portable-92110079 but version 2 is on the horizon and much better, lighter etc…
G
I wonder if his body is acting as a second reflector.
Yes to a certain degree. But this is tru with any hand held Yagi
Large diameter elements give an antenna slightly greater bandwidth than thin elements. If those wide pieces of foil act like large diameter elements, that would be another advantage.
The repeated mention of tape is making me somewhat curious, but my gut, which is well known as a completely scientific instrument for simulating antennas, says even thin wire with otherwise good properties and good connections and geometry would not be left in the dust by a bit of taped-together stuff just because the tape is wider in one axis (but thinner in the other one). I am becoming somewhat tempted to hook a nanovna up to a representative antenna of each sort and judge the shape of the plot though.
Do it! Write it up and submit it to the Hack-a-Day tip line! I’d love to see the results of such an experiment.
I’d do it myself but lack the equipment.
I’ll keep that in mind!
Yes please do! I will be doing some tests like this in the future and it would be good to have confirmation or bias for that matter. It helps us all understand
Element dimensions are certainly relevant in mag loop antennas.
A nanovna will give you return loss, but not radiation efficiency.
They don’t always happen to peak at the same time.
Better still, point it at a distant source (e.g. a repeater) and measure RSSI.
Sure. Well, it’s better than that in this case because of the part where it can plot the vector instead of just the VSWR / return loss. The missing power that isn’t reflected or radiated must be dissipated as real power (heat) in a real resistance somewhere.
So I would look away from the real part of the vector, and expect a higher or lower bandwidth to be visible in how quickly the imaginary part becomes excessive across the frequency sweep. For a plain old dipole around its normal operating frequency and far enough away from complicating factors, it seems like it’d give the right answer. Testing for signal strength at a distance would add in how well it matches a radio which is a separate though valid question.
Years ago I had the idea of making a similar antenna for WiFi by using the same copper tape but inside a laminator sheet which makes it also waterproof and easy to carry in a pocket, but never went further to realize it. With a big enough laminator one could make antennas for much lower HAM frequencies; I’m not sure they do exist though.
Used to be that laminating film came or rolls. Nowadays i suspect the car wrap people have really big materials
Love the idea of showing up to one of these shops with a roll of copper tape and asking if they handle non-car jobs…
Next Stop, a umbrella Version.
Interessting idea, if i hand sew copper wire in the umbrella fabric in a antenna shape. In this way i can sew several Antenna shape in one portable umbrella. And for conneting i need a pair of clamps.
Would a kite version not a better idea?
Noted :) Might try that in the future
Niceeee :)
I’m thinking about doing a dual band version of this for satellite work.
YES! Please contact me via my videos and let me know how it works for you.
I was unable to find how many watts he was transmitting with in this article unless I missed something.
I will assume it was a handie talkie with maybe 5 watts?
73’s
Wouxun uv8r is about 5-6 watts out max so yes a safe assumption is 5w
Put me on your contact list when you come up with a kit
Happy to wait until you come out with an improved vs.2. Thanks
Love to. The best way for that to happen is to get on my Patreon (Join as a free member) and then when it comes out you will know. Thanks for the interest! 73
This is along the lines of what I’ve thought of. I’d call it roll-up not “pocket” sized. Rolled it’s still able to be flattened out rather than two way folding which just wrinkles it all up. Keep the whole sheet of fabric no need for nationalism unless it’s for windy sites. Over here that flag shape gets political.
Now as to the width and bandwidth factors let’s think next about metalized Mylar and inflatable antennae, or foil on plain Mylar. Air deployment, no rods.
Awesome ideas thank you! 73
metalized mylar balloon inflated with helium and tethered via rg400 to your HT thru an antenna tuner?
While kites have been used forever to put up antennas, you could make the yagi into the body of the kite itself… roll it up and let it fly. Doesn’t take much of a skeleton to make it stiff enough to use on the ground also.
A Yagi antenna is really not bulky. It’s not bulkier than the design realized here. Look into Arrow antennas.
I’ve used copper foil for years to build dxing TV antennas in my attic. My truss ties are nearly perfect for turning my attic into a massive vhf yagi with directors