Turnstile 137MHz (145MHz)


What is the right spacing between the passive and the active elements? My antenna has a lot wider spacing as the antenna I saw here in the SatNogs project. Ok. My antenna was build in 2008 or 2009 and I can’t find the site for this again :joy_cat:.

Where can I find the building instruction for a very good turnstile antenna?


I use this type of antenna: https://www.diegorispoli.it/images/articles/antenna-turnstile-noaa.jpg

I don’t have build it myself, but the dimensions are nearly the same,
it’s from the small but nice “Winkler Antennenbau”.


Also the dimensions of the l/4-50Ohm-delay-line and the 2x75 Ohm // matching-line are nearly the same as in in the link. The distance between reflector and radiator is 45cm.

Hi Alex.

Thank you. Ok. There’s a 45cm spacing. Lot less as at my antenna. Is there a calculation formula for this spacing out there?

Or: Has @satnogs a building scheme for a turnstile?

https://wiki.satnogs.org/Antennas does not show build instructions for a non-rotator-antenna. There’s a link to https://en.wikipedia.org/wiki/Turnstile_antenna.

I don’t think, there is a formula for calculating the space between reflector and radiator.
It’s experience, with this spacing of lambda/5 you get a lifted diagram in the vertical.

You get the most gain for satellites with low elevation, the higher the elevation of the satellite becomes, the lower the antenna-gain becomes, but this compensated because the satellite get’s nearer.
The lowest gain of the antenna is, when the satellite is direct above you.
Sorry about my english, i hope it’s clear what I mean.