How to make a fractal antenna for HDTV / DTV plus more on the cheap

Picture of How to make a fractal antenna for HDTV / DTV plus more on the cheap

This instructable is from:


and submitted by William Ruckman of http://ruckman.net

Showcased in the March 2015 issue of Popular Science Magazine:


The first thing I would like to discuss is a little history, theory, and uses for fractal antennas.

Fractal antennas are a recent discovery. First discovered back in 1988 by Nathan Cohen and later published and patented in 1995. A fractal antenna has a few unique attributes as seen in this definition from Wikipedia:

"A fractal antenna is an antenna that uses a fractal, self-similar design to maximize the length, or increase the perimeter (on inside sections or the outer structure), of material that can receive or transmit electromagnetic signals within a given total surface area or volume."

What exactly does that mean? Well, you need to know what a fractal is. Also from Wikipedia:

"A fractal is generally a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole,a property called self-similarity."

So basically, a fractal is a geometric shape that repeats and appears over and over no matter how far out or how far in you zoom magnification.

Source: Wikipedia and http://patimg2.uspto.gov/.piw?PageNum=6&docid=US007088965 Patent number: 7088965]

Fractal antennas have been found to be approximately 20% more efficient than normal antennas. Which could be useful. Especially if you want to make your own TV antenna to pick up over the air digital or high definition video, increase your cellular range, wifi range, FM or AM radio reception, and so on. Most cell phones already have built in fractal antennas. If you noticed in the past few years that cell phones no longer have antennas on the outside. That is because they have a internal fractal antenna etched on a circuit board which allows them to get better reception and pick up more frequencies such as bluetooth, cellular, and WIFI all from one antenna at the same time!

Wikipedia info:

"A fractal antenna's response differs markedly from traditional antenna designs, in that it is capable of operating with good-to-excellent performance at many different frequencies simultaneously. Normally standard antennas have to be "cut" for the frequency for which they are to be usedand thus the standard antennas only work well at that frequency. This makes the fractal antenna an excellent design for wideband and multiband applications."

The trick is to design your fractal antenna to resonate at what ever center frequency you wish to receive. Which means it will look different and be sized different depending on what you want to receive. A little math can be used to figure this out. (Or a online calculator)

In my example, I am going to make a simple one but you may want to make a more elaborate one. The more elaborate the better. I will use a spool of 18 Gauge solid core wire to make a antenna as an example but you could go as far as to etch your own circuit boards for aesthetic reasons, to make it smaller, or more elaborate with more resolution and resonance.

I am going to use the example of making a TV antenna for digital or high definition reception for over the air broadcasts. It is easier to work with these frequencies and they fall around half a foot to a few feet in length for half wavelengths of the signal. I am also going to base it off a common dipole antenna for simplicity and cheapness of parts for VHF. For UHF you may want to add a director or reflector which will also make it more direction dependent. VHF is direction dependent as well but instead of pointing directly at the TV station like UHF you want VHF rabbit ears (dipole antenna) to be perpendicular to the TV station. But there is a little more design to that. I want to keep this as simple as possible as it is already a very complex subject.

Basic supplies (cost me about $15):

Mounting surface such as the plastic project enclosure (8"x6"x3"). http://www.radioshack.com/product/index.jsp?productId=2062285
6 screws. I used steel self tapping sheet metal screws.
A impedance matching transformer 300 ohm to 75 ohm. http://www.radioshack.com/product/index.jsp?productId=2062049
Some 18 gauge solid hook up wire. http://www.radioshack.com/product/index.jsp?productId=2036274
RG-6 coaxial with terminators (and rubber jacket if mounting outside).
Aluminum if using a reflector. The enclosure above came with one.
A sharpie marker or equivalent preferably with a fine tip.
Two pairs of small needle nose pliers.
A ruler of at least 8 inches.
A protractor to measure angle.
A drill and drill bit that is smaller diameter than your screws.
Small wire cutter.
Screw driver or screw gun.

NOTE: The bottom of the antenna is to the right of this picture where the transformer sticks out.

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Step 1: Adding the reflector

Picture of Adding the reflector
Assemble the enclosure with the reflector under the plastic cover.

Step 2: Drill holes and add mounting points

Picture of Drill holes and add mounting points
Drill small tap holes on the opposite side from the reflector in the following positions and place a conductive screw.

Step 3: Measure, cut, and strip wire

Picture of Measure, cut, and strip wire
Cut four 8" pieces of the solid core wire and strip it bare.

Step 4: Measure and mark wire

Picture of Measure and mark wire
Use a marker and mark every 1" on the wire. (This is where we are going to make the bends)

Step 5: Create fractals

Picture of Create fractals
You will repeat this step for each wire. Each bend on the wire will be 60 degrees exactly as we will be making equilateral triangles with this fractal. I used two pairs of pliers and a protractor. Each bend will be made at the 1 marks. Make sure you visualize the direction of each bend first before making it! Use the diagram below to help.

Step 6: Create dipoles

Picture of Create dipoles
Cut 2 more pieces of wire at least 6 inches long and strip them. Bend these wires around the top and bottom screws going longways and contact the center screws. So all three are contacted. Use the wire cutter and trim unneeded wire.

Step 7: Mount dipoles and mount transformer

Picture of Mount dipoles and mount transformer
Place and screw down each of your fractals to the corner screws.

Attach the impedance matching transformer across the two center screws and tighten them down.

BUILD COMPLETE! Test and enjoy!

Step 8: Testing verses store bought antenna

Picture of Testing verses store bought antenna
To see the results of the tests I ran click the link below:



Step 9: More Iterations / Experimentation

Picture of More Iterations / Experimentation
I have made some new elements using a paper template I made in Gimp (photo editor). I used small solid core wire from telephone wire and it was solid enough, small enough, and malleable enough to bend into the intricate shape required at the selected center frequency (554Mhz - as this is the mean of the digital UHF over the air TV channels in my area) and iteration of the chosen fractal design. Which is repeated triangles.

Photo attached. It may be hard to see with the photo taken in low light, the color of the cardboard, and the color of the copper with tape over it to hold it in place. But you get the idea.

At that size the elements are pretty fragile, so they have to be handled carefully.

I have also attached the template in png format. For it to print the proper size, you have to open it in a photo editor like Gimp. The template isn't perfect as i made it by hand with a mouse, but it is close enough for human hands and a needle nose for bending of the elements.

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williamruckman (author) 2 years ago
I have made some new elements using a paper template I made in Gimp (photo editor). I used small solid core wire from telephone wire and it was solid enough, small enough, and malleable enough to bend into the intricate shape required at the selected center frequency (554Mhz - as this is the mean of the digital UHF over the air TV channels in my area) and iteration of the chosen fractal design. Which is repeated triangles.

Photo attached. It may be hard to see with the photo taken in low light, the color of the cardboard, and the color of the copper with tape over it to hold it in place. But you get the idea.

At that size the elements are pretty fragile, so they have to be handled carefully.

I have also attached the template in png format. For it to print the proper size, you have to open it in a photo editor like Gimp. The template isn't perfect as i made it by hand with a mouse, but it is close enough for human hands and a needle nose for bending of the elements.

williamruckman (author) 7 days ago

Hello Everyone! I just wanted to drop in and let you all know a few things that happened with the project recently. I have attached a picture of a build I did on Plexiglas which is one more iteration smaller.

Also, this antenna was showcased in the March 2015 issue of Popular Science:


There are some more things in the making, but i will hit you with them when it is a reality!

Let's keep the wonderful collaboration going! I can't wait to see more of your designs!

gerry19462 years ago
OK I'll try this again.

I built the fractal antenna shown in the attached picture. Works great. I am 35 miles south of Milwaukee, WI and I receive 20 - 30 stations clearly. I can get Chicago stations but I must rotate the antenna.

Please comment on the circular design that I plan to build. Will it work if there are 20 fractals on the large diameter and only 11 on the small diameter. The large circle is 20 inches in diameter. The small circle is 18 inches in diameter. The fractals are approximately 3 inches tall.

Thanks for posting you instructions for the fractal antenna. Much better than my V shaped coat hanger design.

Sorry if I get multiple images. ??????
Antenna 002.JPGIMGP0566.JPGAntenna 002.JPGIMGP0566.JPG
ku5e gerry19464 months ago

You want to design Antennas, I suggest you use a program like, MMANA-GAL to simulate it before you build it. http://hamsoft.ca/pages/mmana-gal.php
A couple of observations on your idea.
1. You have to be careful with the feedpoint impedance. Your TV equipment uses 75 Ohms. Most antennas, like the fractal and loop antenna I posted above will have a 300 Ohm feedpoint. This is the reason we use the adapter. More specifically a BalUn. In this case a 4:1 BalUn to convert 300 to 75.
2. Your design assumes that the feedpoint will be 75 Ohms, I guarantee it will not be. This is why you have to simulate it before you build it.
3. Antennas want to be balanced (in most cases), your design will be imbalanced so the feed point will have to be moved to achieve balance or a suitable feedpoint impedance.
If there is an impedance mismatch (antenna to receiver) the amount of signal present at the TV will be much lower.
For example if you connect the 75 Ohm coax directly to the feedpoint of the fractal antenna I posted (which has a 300 ohm impedance) you would experience 4.087 db loss. Every 3 dbs of loss is a halfing of the signal. Therefore, you would loose more than half your signal.
I hope this helps.

ghz24 ku5e16 days ago

Your statements are correct, but your math is wrong.

75 vs 300 ohms gives a SWR of 4 and a miss match loss of ~1.9 dB.

A SWR of 8 gives the ~4 dB loss you stated.

A point you didn't cover is that SWR of greater than 3 can interfere with the tuners ability to decode the digital symbols and resulting in a much higher apparent signal loss (signal quality ).

You are absolutely right about modeling and simulations.

AdrianC13 ku5e2 months ago


I was wondering if you could help me out with a few doubts I have.

1. Is the design (like for example the one in this instructable) dependent on the location (city/country/continent)?

2. If it is, what details do I need to find out in order to design an efficient "HD" antenna (transmitted frequencies or other stuff maybe)? If so, any suggestions on how to look them up?

3. Do I need a BalUn regardless of the design of the fractal/antenna I make or is the design dictating if I really need it? I ask cause I found a "box" design in youtube where they basically just stapled the narrow end of the antenna to the coaxial, no balun, but then you mentioned that most antennas will need it.

Thank in advance for your help! :D

gerry.friso ku5e4 months ago

Thanks for your comments. I have moved on from the circular design. It did not work as well as the rectangular design. I built a larger (More Fractals) antenna which worked quite well but it was large and not very attractive.

ku5e gerry.friso4 months ago

Gerry, I am a HAM radio Extra class operator, and have studied antenna design a lot. My hobby relies on it very much. One thing that is not mentioned in this instructable, partly because it is out of the scope of it, is that even number of elements tend to work better. Keep that in mind when creating antennas. Also when you have stacked elements it is a good idea to have half of them out of phase to the others.
What this means is that if you call one wire A and the other B, have A going to the left side of two elements and then to the right side of the other 2 elements. You can see this in the design I posted a few days ago in this forum. Good luck and have fun experimenting. That is what it is all about!

gemluvr gerry194611 months ago

The circular fractal antenna that you have showing in a diagram - did you make it yet? How did that work out?

chuckr444 months ago

Can't you paint this shape using liquid conductive paste?

ku5e chuckr444 months ago

You could, but it would be very thin. The thiness might limit the antennas bandwidth (frequency range). This antenna needs to receive from (470-698 Mhz) which is pretty wide.

ku5e made it!4 months ago

Here is my version 8 elements. After building it I found that I had poor reception in the HI-VHF (7-13 {174-216 Mhz} area. While there are not that many DTV channels that use this range, here in Orlando, Fl, one of the major channels is Channel 2 and it uses DTV Channel 11 (198-204 Mhz). The frequency is not quite UHF, in fact it is very much VHF. This Fractal antenna is designed as a great performer in the UHF range (470-698 Mhz), but not so much n the lower frequency range.
In order to remedy this I added a full wave loop designed around 195 Mhz, which also the center frequency of the HI-VHF range. I then connected it to the end of the phase lines. This works because at UHF frequencies the loops impedance is so high it does not effect (much) the UHF part of the antenna. And the same is true for the UHF's section impedance when using VHF frequencies.
I put it together and tested it and all the channels listed on antennaweb.org were viewable.
This antenna works almost as good as the huge Grey-Hoverman/Cat Whisters I presently use.
Pictures attached.
1. Antenna on my jig board
2. My design on paper with loop dimensions
3. My Cat Whisker Antenna

AnithaG17 months ago

hi friends,

Am going to do research in fractal antenna can anybody say what recent problem in fractal antenna? and how to find recent problems in fractal microstrip patch antenna?

davidbarcomb8 months ago

Very nice instructable, clear and concise.

AaronW39 months ago

I got a 6' coax for $4 and the transformer for $3 off of ebay, both shipping quickly from the US.

JeypiB10 months ago

I'm late reading this blog but I find it a good and helpful. I cant wait to do this It is a good thing I've read this <a href="http://rcaantennas.net">How to Install Antenna</a! I can't wait to do this!

burnerjack0110 months ago

Making a jig on a board using small nails or screws would make this go very quick and very repeatable. I can't wait to do this!

gemluvr1 year ago

Holy CRAP! This is COOL!!! I want to try and make this stuff! I'm finding it's answering questions I've had when reading all the posts. This is GOOD!!!

MrEggsalad made it!1 year ago

I took some copper wire and an old coat hanger to create my fractal antenna. It works really well, certainly far better than a standard ~$15 antenna and references suggest it works as well as the best of indoor antennas and even a decent amount of outdoor antennas. I did notice that initially my reception was lower than anticipated, but I upgraded the cable used to connect the antenna to my TV and that fixed those problems which were likely due to poorly shielded cables.

Dalmo2 years ago
Hy guys! May I do the Fractals with 12AWG wire? Because this wire we have!
SpikeG792 years ago
Just made 2 of these 'fractal stars' design that is in ToriAmos' post to add to my original Ruckman design antenna and gained about 5-10% signal strength on all channels. Very impressed :). I added them to the screws that held the transformer terminals. The 5 major network channels now come in @ 80-100% from 70-90%. One new local lower powered station strength went from 50% - 65-70% and is now watchable. I made them with 20 inch lengths of coat hanger wire so there's about 1/2 inch between bends, they take up about 5 inch x 5 inch square area. If I would have made them 10"x10" square area you would need about 40 inches of wire and 1 inch between bends. Hope this info helps.
SpeakerBoy2 years ago
I've made a version of this using ¼" adhesive-backed copper foil tape (the kind used by stained-glass hobbyists) applied to a sheet of acrylic, (without a reflector) and the results were both beautiful (think "Copper Snowflake Sun-Catcher") and impressive. By printing out your template and lining it up with match lines I put on the backside of the acrylic sheet, I was able to apply my strips of foil directly over it in the appropriate places. The adhesive is NOT conductive, but a few well-placed needle pricks soon cured that problem. Once I found the "sweet spot" in my bedroom window, it was performing just as well as my Gray-Hoverman (with reflectors!) while taking up a fraction of the space. It's an elegant little solution for apartment dwellers! I can't thank you enough!
jschwab4 years ago
I've modified the design to increase fractals, adding another set of fractal "whiskers" giving 3 sets per side and iterating the fractal shape several more times, while still fitting into the same compact space.

bending the wires is a little time consuming, but in theory it should add more stable reception. i thought it might be helpful if anyone else was curious about increasing the fractal bends.

Attached here is a pdf for use as a guide / template.

Also, this can easily be mounted to cardboard, pexiglass etc and placed INSIDE the project box, to conceal the antenna.
On the 2nd design fractal antenna. The distance between the bends is much less that the 1" on the 1st design. What should the distance between the bends be on the 2nd antenna?

Are there a couple of segments missing from the free end of each loop? It seems like there should be 5 small identical loops within each main loop. I have a modified version and would really appreciate it if someone could tell me if I have done it right.
for this design do you use all 6 fractals or could you use four like in this ible?
At what size should I print this template to achieve the same center channel as the one from the main instructable?
I printed mine at the default printer setting for a full 8.5 x 11 page. hope this helps.
So, does the image take up the whole page?
If you print with no scaling it should take up a little more than half the page. mine came out centered on the sheet of paper, with the longest edge measuring around 6 inches.
Thanks for the help, and thanks for an awesome Instrucable.
Using this design, how would I attach the dipoles and transformer
you would attache dippoles the same way as the original, at the apex or top of the fractal "star" pattern.
I used your increased fractal design. I got very good reception from an 8x10" surface area. I did not get notably better reception than this design: http://uhfhdtvantenna.blogspot.com/

but the fractal design is smaller and safer (no pokey bits sticking out).
Both designs are electrically the same. One design just happens to take up less space, which will let you cram more antenna into the same space--which makes them work better. More antenna == more gain == better reception
jschwab jschwab4 years ago
update: the original design gave me 56 channels.

with increased fractals (like the pdf above) i now get 88 scanned channels (southern california). that's a pretty significant improvement.
jkunken jschwab4 years ago
I have used DIY homemade antennas within the last two years to receive HDTV with no complaints. Decided to try out this new antenna model for kicks and giggles. With the increased fractal resolution, along with a reflector, we were able to pick up channel 38.1 beaming from Santa Barbara, CA directly from San Diego, CA, over 170 miles away. Signal strength and quality were both > 50%.

With the reflector and this type of antenna, directionality is key. By shifting the antenna's azimuth by only 12 degrees East, we lost Santa Barbara and began picking up Mount Wilson's signals (pretty much all Los Angeles channels), also from San Diego (only 100 or so miles away); still damn good, however, reception is tightly locked, though also *very* stable. Sans reflector, there is an increase in the number of channels from adjacent broadcast antennas, with additional stability introduced from the fractal design.

Great job.
Hi jkunken. Your input on the Fractal antenna caught my eye since I live in the San Diego area as well. If I may ask, on these channels your getting from Santa Barbara and LA area, is your antenna still the same size (perimeter) as the one shown being made here with just more fractrals? And is it mounted outside and elevated? You could be in a vary good spot for reception. Since I want to make one of these as well, I'm waiting with antisipation. Thank you. Garrison
Hi garrison111,
we used the increased fractal design as a basis (same perimeter). We then mounted the antenna on the focal point of a Dish Network satellite dish, with the dish facing North, from San Diego. The dish sits on our balcony; second story, though we also have trees in the way. It has been several months since the system was put in place and we still receive 50+ channels, mostly from Los Angeles, though we also receive adjacent channels from San Diego.
Thank you for replying jkunken. I'm sorry I didn't get back sooner. My Mother is recovering from surgery. Using the focal point of the Dish Network sat dish was brilliant! Because of the dish being a parabolic shape, it means everything being reflected is hitting the antenna. Great Idea! I have several questions if I may ask. Where would I look to get get a used sat dish? Is the antenna still mounted in a vertical (up-right) position or is it turned 90 degrees on it's side as shown in one of these photos that someone did? Are you able to get any lower band channels, say 2 ~~ 13?
I few years ago, I bought and put up the most powerfull antenna that Wineguard makes. I live a little way down from the top of a hill in National City. The antenna, 9 feet by 14 feet was raised 48 feet from the ground. I was able to get a lot of channels out of LA as well but they were unstable coming in out all the time. The wind from a storm in Dec of 09 blew my telescoping pole system in half. And that was the end of that. But you managed to do the same thing with far less. Are your LA channels and beyond stable? Thanks for your input jkunkin and waiting your reply. garrison 111
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