Saturday, September 06, 2008

The QFH (Quadrifilar Helix) antenna

...Another day, another antenna.
For an long time I was wanting to receive weather images from satellites but lack of time had placed in standby my desire.

After getting the first images with the Kenwood TM-D700 it was time to get an dedicated receiver. Checking the available options including building one I opted buying one from Miroslav (OK2UGS) at his website
"Miro" was at the Ham fair in Germany so it took some more time to send me the receiver but as an compensation he sent me one pcb board for an DRM receiver (I have now another project in standby, hi)
After completion of the receiver (was a matter of putting it on an box, it come allready built).

I decided to make some tests with different antenna designs I saw at the web. Soom I arrived the conclusion the for the right job the right tool so on to make an QFH antenna.
The best (best relation between instructions/cost/easiness of construction) design I saw was the one at: although for a total understanding of connections the schema at is more clear (he has an nice use for some ready available materials, hi)

The antenna was build with ready available materials ;electricity tube VD16 and VD32, RG58 cable and electrical isolation tape and some more self amalgam tape. Total cost was around 15 Eur I think, excluding my time :)
The dimensions you can get from the above sites and the images are bellow.
I am quite satisfied with the image quality but still trying to improve. I use wxtoming software running in Linux. Please read the wxtoimg FAQ if you are not getting nice quality (I had some problems by not reading the FAQ).
At the moment I am putting the images received at:

The antenna during build process.

Some measurement:

And this is my "radio" horizon from South (left side of image) to North (right side of image).

73 de CT2GQV

p.s. Are you an English native? Probably you can correct my lousy English, we are allways learning so all comments are welcome!