IIRC we used to use large coffee cans as a feed horn when I did the old analog weather satellite stuff. Maybe we should look at that too?
If bragging is in order I can claim to be an Extra Class ham radio operator with licenses in 7 countries. I have a degree in RF Engineering from Val Pariso Tech (can you guess how old I am?) and I also have a RoSPA Cycling Proficiency Certificate.
What about a yagi? Easier to make than a helical of equivalent gain?
I think the holy grail is a trace antenna.
Back in the days of BSB (later to become BSkyB and then defunct) we used to use a âsquarialâ.
It was RCHP, had a preamp and if you wanted to hack it for use with the French satellites you had to take it apart and reverse the antenna inside. The âantennaâ was lots and lots of dipoles printed in foil onto a clear film similar to that used on overhead projectors.
BSB was KU Band but I donât see why we cannot try one for L-Band?
Yagiâs are simple to make. The issue would be to get the co-ax phasing harness cut correctly. We can have it made professionally to exacting standards but homebrewing is very hit-and-miss. At 440 and 145MHz itâs somewhat trivial.
The phasing harness (for those that donât know) will create the correct phase or (handedness) to the antenna. It creates a delay in the reception (or transmission) of the wave as it travels through the antenna.
I looked at dimensions and figures and quickly adandoned the idea of a yagi.
Anyone ant ideas for a phasing harness for quad helicals? in theory, double helicals will get down to 70 ohm, but then? Read somewhere that 7/4 lambda should do the trick, any ideas?
sidenote: I think outernet is really exciting for all, I got âHey man, thatâs coolâ in the park when I test antennas. from 6 year olds.
Erm ⌠Should we be worried about this? 
I decided to attempt a home made antenna, with the requirement that I had to use whatever I could find in the garage and junk box.
After Googling the dimensions for a proper helix, I had a tough time finding anything the right diameter to support the wire and then discovered an old paint roller was the right size. Used the bottom of an old foil pan for the reflector. It was too flimsy, so I used some spray adhesive to attach it to hard cardboard for support. Used an old SMA male to male coupler by cutting one of the nuts off, pushing it through the cardboard, and soldering the center conductor to the wire. Made sure the outside made a good connection with the foil pan. Then I used hot glue to keep it all together. The wire was stiff enough that it stayed in place on the roller with no help.
The piece of wire that I used, which was already cut, resulted in six turns with the last 1 1/2 extending past the end of the paint roller. Itâs not perfect, but I was getting a 6+SNR with a spare E4000 dongle and NooElec LNA which I have not tested with a proper patch antenna. That was also while trying to aim through openings between trees and branches.
I had to try. Itâs not pretty, but it works! Junk box engineering succeeded. But, my second Outernet Patch Antenna should arrive tomorrow anyway. The patch is much easier to aim.
@Abhishek @zoltan Youâve got to see this.
Iâm surprised that it would be harder to aim this, assuming that is provides similar gain, then beam width would be the same.
In real life, Iâve found that the patch is happy if it is just pointed in the general direction of the sat. My helix had a much more severe signal drop if just slightly off aim.
@syed, The difficulty in pointing the antenna is due to the radiation patterns. Helical antennas have a very strong pickup at the center (0 degrees) but quickly fall off when off axis. Patch antennas support more off axis pickup with the sacrifice to a center (0 degree) gain.
The opposite, They were asking what I was doing, and bright-eyed that I was receiving satellites.
I hope youâre hungry.
Rtlsd4everyone: âInteresting. A friendly greeting in the West. A cruel taunt in the Sudan. Itâs a lesson in context.â
I tried the L band spiral antenna RG58 zip tied to a broomsitck the outer braid connected to ant and the cardboard and ultra heavy aluminum foil ground plane to grnd of the LNA. I was down around 1.5dB snr, not enough for Outernet packet rx.
I kludged my RTL dongle and ripped off the ant trace when I desoldered the connector and had to do microsurgery to connect the SM cap to the center connector of my coax, and the outer mount pads to the braid.
I have one of the $25(sold out) integrated Outernet USB-SDR-LNA-antennas coming in the mail but I prefer to have the option of hacking my own equipment. I also have more LNAs, RTL-SDRs, connectors and bulkhead SMA connectors for more DIY attempts.
I would like to see more easy to make DIY antenna hacks discussed.
I have found cantennas are easy to measure out back in the early wifi hacking days though probably too low gain and wrong polarization, DIY patch antennas difficult because sourcing large enough cheap solder-able brass or copper sheet, this is also a limitation of the groundplane on the OPâs spiral&cookie tin antenna.
We also need to include cheap well documented and drawn antenna and receiver designs in the satellite feed, perhaps some highly compressible animated video. Most valuable would be requesting form the amateur and academic communities a variety of designs including the most easy to understand line art and instructions for using and modifying the cheapest Realtek DVB-T dongles available at many TV, computer, and phone shops or hardware stores, using and making LNAs, soldering bias-T connections on various SDRs and LNAs, and especially making the easiest L-band antennas.
A goal of the 3D printing movement are printers which can themselves 3D print many of hard to source parts excluding the electronics and motors.
Outernet, whoâs main income is from donation not selling bespoke hardware at or below cost, should be in the business of proliferating functional Outernet receivers from whatever a user can easily acquire locally even if the official hardware is out of the price range; in order to increase the number of humans receiving benifit and thus increasing the total value of every donation and donation request.
We need to create a situation where one Outernet earth station can proliferate more Outernet earth stations in as many official and tested DIY configurations as possible using as much cheap appropriate technology as possible.
I can put 100 small Realtek DVB-T SDRs in a beltpack or wrap in a sleeping bag, maybe 50 SDR and LNA combinations. A similar number of connectors and a spool of coax or direct connectors. Easily that many CHIPs or R-Pis fed over USB to a computer or tablet running the decoder but antennas for L-band are small, but not as small as a RTL-SDR and LNA.
