Hi Matt,
are you referring to a turnstile antenna like the one available from WIMO here in Germany ?
Please see the following link: http://www.wimo.de/download/ta1.pdf
Best regards
Matthias
www.dd1us.de
-----Ursprüngliche Nachricht----- Von: [email protected] [mailto:[email protected]] Im Auftrag von Jonny 290 Gesendet: Freitag, 28. Februar 2014 20:50 An: [email protected] Betreff: [amsat-bb] Inverted-V turnstile idea
I had an idea pop in my head for a simple turnstile antenna, and am not finding much info on what I want to do via Google searches I wanted to bounce this off the list and see what people think.
My idea consists of three main points:
-Antenna elements being conventional (non-folded) inverted V dipoles, tuning the length for resonance and angle to set at 50 ohms each -1/4 wave 50 ohm phasing line between the sets of dipoles -Feed via DK7ZB match using a 1/4 wave paralleled 2x75 ohm line section (37 ohms), transforming the 25 ohms back up to right around 50 ohms for final feed
This approach would give the following advantages:
-Lower SWR than standard 75-ohm parallel turnstiles -Dipoles could be individually tuned via direct 50 ohm feed during construction -DK7ZB match is constructed out of inexpensive 75-ohm coax -Phasing line length would only affect phase, instead of phase and impedance.
My main question, though is: With dipole elements canted down roughly 35 degrees from vertical (what I'm ballparking to get them down to 50 ohms), am I going to see noticeably degraded performance, especially regarding the polarization?
Thanks for any tips or discussion!
--Matt KC4YLV _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb