Fractal fail. This one wins the most-annoying-home-project-ever award. I found some online instructions for a "fractal" HDTV antenna on Instructables. [here] On first glance it looked more simple than the Bowtie model I made a few weeks ago. Flush with spare coat hangers and scrap wood from that prior project; I gave it a go. It started off very simple. Cut some plywood...
...Sand and prime it.
...Sand again, and paint it.(This part ain't rocket science)
Then measure and mark out all the holes... cut the 8" lengths of wire for the aerials. I won't rehash all the instructions, it's not wildly different than the home-brew antenna I made late last month. [here] I didn't stop until I got partway through the instructions. Then something went wrong. With a fractal antenna the idea is that you are shaping the aerials with self-similar patterns, the angles and lengths are very specific.You'll probably see it right off, but I just wrote down the numbers and made my cuts and bends.
For the record, fractal antennas are a very recent discovery. They were first discovered in 1988 by boy genius Nathan Cohen and patented in 1995. The fractals resonate to tuned frequencies and make the antenna much more effective. Most manufacturers just print fractal designs directly on circuit boards. That allows them to make smaller and more intricate fractal designs without the changes in resistance you get bending wire. The antenna gets more sensitive the more self-similar repetitions occur within the design. The one I messed up was actually quite simple. Next time I get some scrap copper wire I'll take another shot at this.
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The picture looks off, the bend in the middle of the wire is not 60 degrees acute or obtuse. Cell phones make great use of Fractal Antennas. The theory is simple enough, I just think this guys instructions are not that great. Try this one, it has a good way to make a template, which is easier than using a protractor.
ReplyDeletehttp://www.bobmc.net/doku2/doku.php?id=hdtv_fractal_indoor_antenna
I know that real fractal antennas really work. What screwed me up was just writing down the measurements and angles on scrap paper then building it. If I'd stopped to think about it for a sec,I'd have realized they can't all be 60 degrees. The result was mangled coat hangers and nothing that resembled a real fractal antenna.
ReplyDeleteNext time I get a bit of scrap copper I'll try again with that diagram. Looks simple enough. I wish a had a better handle on the math. Now understanding the concepts better I think I could build something much more complex.
I know this is an old post but the easiest way to make the designs is to create your own template. You just have to print out the design, place the paper on a scrap piece of wood, nail in headless nails at the points of the design. Follow the design on the paper and shape the wire around the nails.
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