Friday, April 23, 2010

The Amazing KGD

On the WSPRnet website DM1RG posted some results obtained using a 30m dipole 1.3m long, the "Kurz Geratener Dipol". His 5W signal made it all the way from Germany to Australia. He finds the KGD to receive only 3 to 5dB worse than his "big vertical antenna."

I tried translating the article about the KGD using Google but it didn't make enough sense for me to understand how to make one. Perhaps someone will figure it out and publish a better explanation. It looks to me to be an interesting idea for anyone with antenna restrictions or simply wanting a second antenna so they can run WSPR or monitor a band while they operate somewhere else.

4 comments:

M0JEK said...

Have looked at the KGD sometime ago myself. QRPproject.de used to sell a version, but discontinued it for some reason.
From the reports I have read, the coils can get very hot, so hot that if you use PVC formers, they will soften. :-)
If I get the time, I might try and make one, I have found English notes somewhere, just need to find them again!

M0JEK said...

Have you seen this page Julian?

http://www.nonstopsystems.com/radio/frank_radio_antenna_KGD.htm

Might be a help.

73

g4ilo said...

Thanks! The page in English is much easier to understand! Mind you if the coils get hot, it suggests the antenna isn't very efficient. And the need for a very high voltage capacitor presents a constructional difficulty. But it might still be useful as a dedicated antenna for low power WSPR use or similar.

Anonymous said...

I'm currently experimenting with a derivate from the KGD-antenna. I could not find precise building figures (coil turns and capacitor value). So I went on my own and build a 40m prototype dipole made of a central coil covered by a coupling coil (no capacitor).

Due to severe antenna restrictions I use this as an indoor antenna, QRP only. Of course, under those circumstances I noticed no coil warming up problems.

I made some nice QRP QSO from Belgium (Moscow, Bucarest, Belgrad).

I build also a serie of MicroVert DL7PE antennas (80, 30, 20m).

These are all compromises, but allow me to put some sigs out...

CU on the air...

73 de Jake