[amsat-bb] Re: Inverted-V turnstile idea

[Jonny 290]

Yes, that's exactly what I had in mind! So it very well may be a viable
design, then.

--
Matt

-jonny 290


On Fri, Feb 28, 2014 at 2:51 PM, Matthias Bopp <matthias.bopp at gmx.de> wrote:

> 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: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] Im
> Auftrag von Jonny 290
> Gesendet: Freitag, 28. Februar 2014 20:50
> An: amsat-bb at amsat.org
> 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
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