Dreamcatcher passive antenna

Just received my Dream catcher board. I got it set up reasonably quickly with Skylark OS. I didn’t purchase an antenna as part of the fun is building one. I live in Aberdeen Scotland and the elevation is 20.8. As I live in town this presents its self a challenge getting line of sight. My first attempt was a patch antenna. This worked marginally with only 2.5-3 dB. So thought I’d attempt a helical antenna. I used a roasting tray as the reflector and twisted brake line for the nelix. Couldn’t believe it a clean 8dB of gain!!


It goes to show you how one can take things from around their house and re-purpose them. Now that you see the basic principle works, you can make a more permanent one. There are several YouTube videos that show you how – using a PVC Pipe and a more solid reflector. Depending on the design, you might need a matching stub as well.

Yes. That’s the next step. Very satisfying throwing something together and getting very reasonable results, Glad I had that roast chicken the night before.

It’s been running all day now and received over 29000 packets with no errors. The weather app is very cool. Away to find some more permanent HW for the real antenna.

…That’s my next project! A Helical antenna for L-Band. Do you still have your dimensions?

–Konrad, WA4OSH

Use this calculator,

Diameter was 6.2cm and 5cm between spirals. The tray is about 23x29cm the last quarter turn is parallel to tray in an attempt to match.(seen this else where)

1 Like

I have tried my 10 turn helical and it has about 5 dB more gain than the active patch receiving Outernet. Have re-purposed the helical right now, for the patch is fine. Getting 8-9 dB SNR, sometimes over 10 in Los Angeles.

Don, W6RWN

1 Like

I’m surprised no one has tried to make an L-band cantenna yet.


1 Like

It would be a coffee can antenna on L-band. The diameter and distance between the driven element and the back of the can (reflector) do matter. These dimensions are for 2.45 GHz Wi-Fi.

The gain of the air gap passive antenna is about the same. This one will have better looking side lobes.

Also, remember for satellite work you need right hand circular, not horizontal or vertical polarization.

Helical antenna dimensions:

Wouldn’t using a linearly polarized antenna cause a 3dB hit?

Yes a mismatch in polarization (linear-circular polarized) will cost up to 3dB.
Crossed polarization between RHCP and LHCP can cost up to 30dB.

Here is Intelsat’s take on the subject:
Intelsat: Linear vs. circular polarization

–Konrad, WA4OSH