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This instructable is from:
http://ruckman.net/archives.htm#FEATURED
and submitted by William Ruckman of http://ruckman.net
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.
http://ruckman.net/archives.htm#FEATURED
and submitted by William Ruckman of http://ruckman.net
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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Signing UpStep 1Adding the reflector
Assemble the enclosure with the reflector under the plastic cover.
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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.
but the fractal design is smaller and safer (no pokey bits sticking out).
Thanks
with increased fractals (like the pdf above) i now get 88 scanned channels (southern california). that's a pretty significant improvement.
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.
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.
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
yes, the satellite dish increased the gain quite a bit. The antenna is mounted vertically, not on its side, and in fact, most of the stable LA channels the antenna receives are in the VHF range (2 - 13), in addition to a variety of foreign language channels in the UHF range, of course. This is remarkable since DTV reception is based on the UHF range, afaik. One of the keys to stability is minimizing the use of splitters, since the signal can drop by several dB, as well as keeping coax cable lengths to a minimum; the longer the cable the greater the reduction in stability, say, if the cable is moved around. I believe tripods and satellite dishes can be purchased for around $100 from companies selling OTA receivers.
Good luck with your project.
It's great that this antenna can pick up both UHF and VHF bands. On the loss of db, if an amplifier is placed close to the antenna, that should compinsate for line loss.
On the dish search, I jsut remembered. I believe and have seen them being sold on craigs list pretty cheap.
Thanks again and waiting your reply. ~~ garrison111
http://www.kwarc.org/ant-calc.html
Thanks for the instructable! It is really cool. I came across your design the other day and decided to try it out this past weekend and it worked pretty good, just in my living room and with no reflector. My antenna is made with 8 dipoles instead of 4. I sort of combined your design with the bowtie design. I was able to pick up all the same channels as my two uhf only antennas from Radio Shack. Granted I had to rotate the antenna to aim it in the right direction and not all signals came in as strong.
The antenna is not totally finished. It's still missing a reflector. I've read on some other sites that wire mesh might work better as a reflector, as opposed to a sheet of aluminum. What do you think? Also, is the distance between the dipoles and the reflector important? My dipoles are on mounted on 1/2" plywood stick. If I put the reflector on the opposite of the plywood, would it be too close?
I am going to try to add this antenna with my existing two in the attic and combine all the signals into one to see if it will improve my reception. I plan to point all three in slightly different directions to be able to pick up all the stations. I don't have a rotator.
Thanks again for the cool design.
.
There is probably a way to print it with conductive ink... then you could glue it onto about any (insulating) material you have handy, connect the terminals to a tranformer or a cable connector and plug it in! ,
If it gets damaged or worn print out a replacement! Even print several copies and build an array.
.
Tin foil or a matel screen (strainer, etc.) makes an excellent reflector. Suggest you experiment with tin foil, scissors and scotch tape.
BTW your average log periodic (fishbone-looking) antenna is also a fractal.
My problem is, I live about 45 miles from the towers (Beaver dam to towers in Madison wi), I get awesome reception with this except for 2 stations that I want.
I was wondering if there was a way to boost reception other than adding an amplifier and without making it bigger. As you can see from the pictures I added a couple elements to the original design to get a better reception.
Aluminum paper on reflector ? can I add straight elements going out of the ones in ?
Thanks for the help!
PS: yes I used a cookie cooling rack I had laying around :)
Next, you're using the cookie rack horizontally polarized and the antenna elements vertical, so the signal isn't going to bounce off the back but go right through it. Also, the signals are horizontal, so turn your elements 90 degrees from the picture and you've got it right.
Doubling your antenna size will get you less than 3 dB so there's a diminishing returns. Better to try to get it higher, especially above any obstacles such as houses or trees.
I forgot to mention, I used the 1" setup, I have a piece of 2x4 (aka 1.5" between elements and reflector or however it's called :)
Do you think that you might consider this Idea for the future?
Thank You. Nice project.
Has any reader written a nec description file so this antenna can be modelled using the xnec2c antenna software program?
xnec2c is a Linux antenna modelling program. There are similar programs for Windows.
What a fine accomplishment in bringing the recent development of fractal antennas down to a practical and build-able level.
Wouldn't the bending go a lot easier if you just pounded a nail into a board, then marked off a dot @ 1 inch on one side then 2 more @ 1 inch after the bend for 60 and 240 degrees?
This works as good or better than the $50 clearstream micron i purchased from best buy.
I am also interested in more iterations on the fractal design, but i cant imagine id be able to tell the difference as i already get 50+ channels with this. if only 40 of them werent in foreign languages. :)