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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
![](https://secure.gravatar.com/avatar/98de8edd700caab9c3cbb2daeb4e2c58.jpg?s=120&d=mm&r=g)
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
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I have 2 of the ELK antennas which I mount at 90 degree angle to each other and switch between as the satellite rotates. My question is:
Could I feed the two ELK antennas which are 4 feet apart, on the same boom and at right angles to each other, in quadrature phase and achieve circular polarization or perhaps decent elliptical polarization?
Thanks,
Doug K9DLP
![](https://secure.gravatar.com/avatar/01fa6a6884b2a8d632405a6dcc7e7d2c.jpg?s=120&d=mm&r=g)
Yes, it can be done. The "Satellite Experimenters Handbook" describes it. I have done it with Arrow antennas.
Here are a couple pictures from our 2005 setup: http://www.w0wtn.org/img_browse.php?i=/images/field_day_2005/p0000016.jpg http://www.w0wtn.org/img_browse.php?i=/images/field_day_2005/KK0SD_Sat_Ant.j pg http://www.w0wtn.org/img_browse.php?i=/images/field_day_2005/p0000017.jpg
It worked very well.
73, Joe kk0sd
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Douglas Phelps Sent: Friday, February 28, 2014 3:14 PM To: [email protected] Subject: [amsat-bb] circular polarization of antennas not on same axis
I have 2 of the ELK antennas which I mount at 90 degree angle to each other and switch between as the satellite rotates. My question is:
Could I feed the two ELK antennas which are 4 feet apart, on the same boom and at right angles to each other, in quadrature phase and achieve circular polarization or perhaps decent elliptical polarization?
Thanks,
Doug K9DLP _______________________________________________ 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
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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 [email protected] 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: [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
participants (4)
-
Douglas Phelps
-
Gary "Joe" Mayfield
-
Jonny 290
-
Matthias Bopp