Detailed building instructions with lessons learned, proof and video available here:
http://www.radioforeveryone.com/p/easy-antenna-for-outernet-l-band.html
Antenna costs about $1, takes less than 30 minutes to build.
Many thanks to Outernet!
Akos
radioforeveryone.com
Very nice… Can’t wait for the pipe version…
You say you used “Outernet preamp”, is that the NooElec produced LNA?
Nice work.
AKOS this is really interesting and I congratulate you on achieving a $1 antenna. I feel this is clearly were Outernet needs to head if it is to get into the poorest parts of the world.
This is awesome. I do agree that the $1 price point is where we need to be. But we’ll likely get there with a ceramic patch.
High Gain $1 antenna possibilities.
The spec for the Ceramic says.
1.575GHz GPS Ceramic Patch RF Antenna 1.573GHz ~ 1.577GHz 3.3dBic
Is 3.3 dBic enough gain? We need with the current patch antenna and LNA a health 9db at the RTL dongle to have enough gain for fade, attenuation, etc.
The advantage of the Helix/helical coiled home made antenna, assuming you can make it bigger. Ie more coils more gain. If we could add enough coils to increase the gain to say 25 db then the poor people would not have to by a a $19 Low Noise Amplifier. So the only thing they would need, in theory, would be a
$9CHIP
a $9.00 Chinese RTL 2832U dongle
$3 Coax.
$1.00 Helical Coiled High Gain Antenna.
Total $22.00
The generic DVB-T dongles use a very high PPM crystal, as opposed to the TCXO with stability of 1PPM that we more or less require. A software update in the future may allow us to support higher drift/offset, though.
An antenna with 25dBi of gain would be very difficult to point. About has hard as a Ku-band dish. But it would be really cool to see!
The goal is to increase the power so that lower gain antennas can be used. This will take some time, but it’s definitely the goal. We will eventually get to a retail product that is just under $20. It will take some time to get there, but some day…
Got a 3D printer? Try these antennas I found on Thingiverse …
By printing enough of the arms you can create a guide that will hold the electrical wire at the correct spacing and angle. I might give one of these a try. I have a Robo3D printer.
Right now, an antenna for wideband LNA is the challenge.
I’m on it, and tonight I managed constant 3dB with two antennas I built. LNA4ALL Bias-T with v.3, double 10 turn helixes. 2nd was LHCP 4 turns and chicken wire.
Don’t ask how and why, I need to replicate antennas two-three times to figure it all out.
PhD thesis level resources only simulate in NEC, I build by trial and error, monitoring SNR (get the nerds to make it accessible by tapping on signal level).
Getting there, I raised the stake to $3. Total cost.
@ Mark whatever, go to Angola. See people fight for empty plastic bottles. Go to Soyo, refuse a child, then give all money and water to parent who beats a whimpering girl. Go to Malabo. Then go home and start thinkin’ on 3D.
I agree with getting a super low cost. I think it is an Honorable quest. Plus experimentation is where Outernet has to be right now. I like your energy.
Excellent Idea Mark. Are any of these antennas L-Band Hi Gain Hemispherical?
“@ Mark whatever, go to Angola. See people fight for empty plastic bottles. Go to Soyo, refuse a child, then give all money and water to parent who beats a whimpering girl. Go to Malabo. Then go home and start thinkin’ on 3D”
Erm … what?
I’m not sure where you are going with this statement.
One of the reasons that I’m trying this is because I’ve been to Angola and other places. I’ve done the Cold Trail. I went with Live Aid to Ethiopia. I’m loosely involved with Ears To Our World whom are an NGO bringing information to the 3rd world…
3D printing may not be available to the 3rd world but it is available to us. Lets face it, we’ll be the ones creating the kits that will get sent to the schools in the Upper Ubangi. We’ll be partnering with groups like OLPC to enable classrooms to get access to this resource. 3D printing is one of the many ways in which we can add to this project by making and testing designs of all sorts of stuff. In turn the successful designs will get pressed into production. R&D of this type will significantly reduce Outernets costs and time to deployment.
My sentiments exactly.
@Mark_Philips,
I apologize right away, I assumed that you’re trolling with 3D, in a forum which says homebuilt. Mea culpa, I was wrong.
3D printing is great, I’d love to assemble a kit which only needs wire. That would cut down on shipping, leading to cost savings, money which could be used for more kits.
A suitable kit could be built for $2 on a larger scale, so only a $2 dongle and $1 worth of coax be needed.
A $10 Outernet station would be possible with 10,000 units or more on an industrial scale. Who’s got that much?
Updated post with new video after making some changes: 17 by 17 cm cookie top, in a different location, got 7-9 dB constant SNR and no packet failure count over 500 packets.
Seems like a larger ground plane get a better result, so the wife is asked to eat more cookies. Let me just say I’m not the only one delighted with Outernet Bottle Helix Mod 2 in the household 
The goal remains: Chip, $8 dongle, antenna. One step at a time, but progress is progress.
This is great progress.
The reflector should be at least a full wavelength across.
How hard was it to align?
168x168 mm.
“Should be” doesn’t work in real life. Sources say 0.75 thru 0.5 up to 1.5 lambda, but all simulated in NEC.
Aligning was no bother, high gain compensated for pointing errors.
I hope I can do more testing tomorrow, was pissing rain here, right now testing 6 turn double.
Trial and error, so many variables. Built wooden frame for 20 turns, doesn’t work reliably. That’s 2 hours, so I go back to max with 4 turns, then 6, then double up.
It’s fuc$#@ing grey area, then you got salad bowls, then reflectors, but I’ll get there.
I am really interested in what you are doing.
I agree 3-d printing is a wonderful way to create things.
But if we can just take a Pringles can and make a wifi cantenna. People who don’t have 3d printers and plastic filament can still make something.
If we can recycle or re-life something into a high gain L-Band antenna we have cut $30 (Ant + Shipping) of the cost of a remote user setup.
That’s why use I use trash. No cost.
Pringles can doesn’t work, it’s a waveguide with a receiving element. Good for 2.4 GHZ, but not for 1542. 9cm outside diameter is too much.
I reluctantly think more and more I should add the fact to the webpage that I’m a college-educated radio officer, who knows what he is doing. People will maybe believe me.
In this field, we’re treading a new path. Nobody has ever done this before in real life, lab simulations don’t count. Go out, build antennas.
I won’t say I got a solution. I fuck up. Every day. Then every day, with every ten failure, I got one success, more and more closer to my goal.
