Saturday, February 13, 2010

Fractal Koch Curve Radio Antenna

Want a radio antenna that will perform better than an antenna of similar size, and look pretty too?
Fractal antennae have been around since 1988, and can now be found in most cell phones. The basic idea is that any self-similar shape will produce better results for broad-band antenna design. See more information on this invention from the inventor himself.
This antenna is based on the koch curve, which is a special case of the DeRahm curve .
To start, download the graphic from wiki, and edit the 4th iteration to fit on a 8.5x11 sheet of paper. (I like to use Gimp, but you may have another preference.)
Print the rsult, and pin it to a cork board. Using pins, place a pin at each point on the curve. You will need to find a wire that is at least 8x((4/3)^3) + x inches long (about 18.96 + x"), x is to reach the radio, 3 feet , so make it 4 or 5 feet long. 8*(4/3)^3 represents the length of the triangle side at the first iteration, 8", multiplied by 4/3 for each iteration. Three iterations will increase the length by a factor of 4/3 to the 3rd power.
Next, you will put a pin at each point, and wrap the wire around that point. try to keep the wire exactly on the printed design. It helps to tape it down as you go to solidify your work. (I used packaging tape so the design is visible) This will take some time to complete (I took 2 hours or so...)
If you want to play around with self-similar shapes, there are some free fractal generators out there. Perhaps a 3d-fractal, a 3d printer with conductive plastic, and bam, youve got a 3d fractal antenna!