Instructables
Picture of Indoors Fractal HDTV Antenna
This antenna design grew out of my attempts to build an indoor HDTV antenna using fractal patterns after  I had watched a TV show and had read a magazine article on the use of fractal patterns in cell phone antennas,  My goal was to design an antenna that not only worked well, but one that was easy to build and could be built from easiliy obtainable materials.

The result is an antenna that is somewhat omnidirectional,  and performs well receiving digital TV signals at my home from the low end of the VHF high-band (i.e Channel 7 at 174 MHZ) to the high end of the 600 MHz UHF band. (There are no channels in the 700 MHz band in my area, but Channel 51 at 692 MHz is one of the strongest signals here.)

This antenna can be used at a maximum line-of-site distance from the broadcast tower of about 50 miles for high power stations, and somewhat less for low power stations.  I'm sorry that I can't be more definite about these distances, but a lot depends upon the type of construction used in the building and the location of the antenna within the building (e.g. downstairs living room vs. second story bedroom or attic).  

So, with all that in mind, let's get started. 
 
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ahmadsadin1 month ago
stellar instructions with great results
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JennieA2 months ago

I would like to know how did you come u with the pattern? What are the parameters you considered?

JennieA2 months ago

How would the frequency affect the design? Our desired frequency is 198-204 MHz.

Firefox6753 months ago

My hardware store has 18 gauge bare, solid copper wire, would this work OK ?

tigers58 (author)  Firefox6753 months ago
Larger diameters of wire should work better at receiving signals, with the trade off being that they are more difficult to thread onto the form and to bend into the sharp corners of the fractal pattern. I have used 18 gauge wire with good results.
cyfus4 months ago

My printer refused to print the design beyond 100mm. no matter what settings I choose. what difference does this make to have it off by 50mm?

PhilKE3FL6 months ago

I see you've put this back up, sure took me a long time to realize that. I'm glad you did. My evaluation of the original is up on my blog at: http://blog.solidsignal.com/content.php/1477-Another-Home-Brew-antenna

jvavruška6 months ago

How did you measure antenna impedance? How do you know it is 300 ohms? How does it change with frequency?

Chro8 months ago

I just tried my hand at making this (wanna watch Cosmos :D)

But unfortunately I cannot get it to work at all!

I used copper wire & followed the instructions. The only think I can think of is I used a Matching Transformer to connect the antenna to an aux cable/TV

In doing this I wrapped the copper cables to the pronged ends of the Transformer cables. Might this be the issue? Do I need to strip the ends of the transformer and remove those pronged ends?

tigers58 (author)  Chro7 months ago

You don't need to remove the prongs; however, you do need to connect the antenna to the Antenna (ANT) input on your TV. The Aux/Cable inputs use different types of signals, such as those coming from DVD players, DVRs, etc., and will not work with an antenna connected to them.

c.r.h.8 months ago

I printed out the pattern for your Fractal Antenna about a year ago and just now made some time to build one. I found some thin plastic to weave the wire through and it does make a good all round general purpose antenna. Much better than the rabbit ears I had been using on our secondary TV. I assume because it is much more omnidirectional.

I was curious, since it took so long to thread the wire, if the antenna would work if I drew it using some conductive wire glue I had on hand (bought previously from Radio Shack). I drew one on cardboard this time and let it dry overnight. Sure enough, that works fairly well too. I used #4 screws and flat washers to make the connections between the carbon traces and the 300 ohm cable. Hot-melt glue works very well as the cable strain relief for the rigid antenna cable.

Some stations came in better while other not as good. That just tells you that these antenna are a little position sensitive, but of course they would be, give the size and operating frequency. One pointer, if using conductive ink, is to bend the cylinder into position before the ink sets up fully, since it is likely not very flexible and may crack when bent after it has dried. There are much better conductive ink pens out on the market and I would expect them to work much better than what I used but I was really surprised to see how well this worked too.

Was curious to know how you came up with the pattern? More specifically the inside pair of traces?

tigers58 (author)  c.r.h.8 months ago

Thanks for the good comments and the report on using conductive wire glue. I spent some time thinking about ways to mass produce the antenna, and it seemed that some form of printed circuit using conductive ink would be the best way to mass produce the antenna. I got busy with other things and never got around to experimenting with conductive inks, so I really appreciate your report.

After seeing a TV program about the fractal patterns used in cell phones to give them a very wide bandwidth, I went on line and did a search for 'fractal patterns' and found the Koch Snowflake as an example of a fractal pattern. I had only been aware of fractal patterns like the Mandelbot (SP?) patterns that were used to generate the incredible patterns is some screen savers years ago, and I couldn't imaging using something like that to make an antenna. So, I choose to experiment with the snowflake because it is so easily reproduced in wire. The inside traces were just an attempt to improve the antennas lower frequency response and were a lot easier to add than the effort that would have been required to punch all the holes and lacing wire that further duplication of the outside pattern would have required.

dpleticha8 months ago

I made mine from some left over Cat 5 wire and an USPS Priority Mail box instead of poster board. If you cut the box right you don't even need tape as you can use the box's adhesive strips for that!

tigers58 (author)  dpleticha8 months ago

I hope the Priority Mail box has previously been used - those things are expensive. :-) I designed a form using poster board and double sided tape that worked really well, but decided that the slots and tabs with a little ordinary cellophane worked just as well, and more people already had cellophane tape in a drawer somewhere.

tyzh made it!8 months ago

I tweaked it a little, wrap directly onto the case, making it a little more geeky looking. However, it does not work well. With just 6 inch of copper wire directly onto coax cable, I can get 50-60 channels, maybe 1/2 of them are watchable (some barely). With this design, it only gets about 20, and the signal is no better.

Did I miss anything? Does removing the cardboard break the design? Thanks

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tigers58 (author)  tyzh8 months ago

The plastic case should work as well as, or better, than the poster board. ????

froze8 months ago

Made two of these so far. Great idea, thank you. The first was made with insulated cat 5 wire (22 or 24 awg). The wire was sewn into a piece of poster board and rolled into a tube. Worked reasonably well. The second was made with the same wire but stripped bare and sewn into a 3-liter soda bottle. That worked better. Not sure if it was from the bare wire or from the slightly expanded template (scaled up a few percent to fit the bottle). I think the clear plastic bottle and the copper wire looks quite a lot better than the poster board version. TA

tigers58 (author) 8 months ago

Thank you for your comments, and I am so happy that it is working so well for you. I believe that taking the extra time to make all the bends in the wires as sharply and uniformly as possible pays extra dividends in the performance of the antenna.

ataylor65 made it!8 months ago

This is a REALLY, REALLY EXCELLENT DESIGN! I have made this, and it works beyond even my most optimistic of expectations. The roof aerial for my ground floor flat with no line of sight to the transmission antenna failed in a recent storm. This tiny antenna is now it's replacement and miraculously receives I think almost every London digital TV signal, including the high definition stations and the obscure +1 stations. Well worth the 3 evenings I ended up spending making this.

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probetox9 months ago

Amazing! good job!

jkuner1 year ago
Success! Thanks again for the instructions. Way more channels than the old rabbit ears. I just used the 75 ohm transformer and soldered the leads to copper wire from the crafting store.
tigers58 (author)  jkuner1 year ago
Thanks for the comment. I'm glad that the antenna is working well for you.
Zoldak1 year ago
Thank you for the excellent instructions for this Indoors Fractal HDTV Antenna! Just made one tonight and am now getting a total of 25 stations.

I cut the cable cord recently and needed an option to watch football this upcoming season. This is going to do the trick for all the local games. Thanks again for sharing your idea!
philip421 year ago
how is different from your previous magic fractal antenna?
tigers58 (author)  philip421 year ago
The word "Magic" no longer appears in the instructable.