I'm still struggling to figure out the best antenna configuration for me. I was originally planning (and now own) to use a Gulf Alpha dual band fixed at 15* elevation, but I am now having 2nd thoughts. Being limited to 1 roof top tower it might be prudent to get as much use out of the single mast as possible. If I go with 2 horizontally polarized linear antennas on a cross boom(1 ea. 2m and 440) could I use them for both satellites and weak signal work? Is there a downside to proceeding this way?
One concern that I have is that the horizontal antennas seem to have a somewhat limited frequency range, and I'm not sure of the impact. Also, is it prudent to go with separate azimuth and elevation rotators to allow for future expansion (6m etc...), although the separation required between booms is height prohibitive with 6m?
Is anyone running a setup similar to this? Are you happy? Any thoughts, opinions etc... would be appreciated,
Zach N4ERZ
Horizontally polarized beams will not work very well for satellite use. For maximum utility, I'd get crossed yagis set up to switch between horizontal, vertical, and circular polarization. Use the circular polarity to work the sats, horizontal polarity to do weak signal work, and vertical polarity to pull in those weak repeater and FM simplex signals.
The az/el rotor set up will work best and give you maximum flexibility in your set up with the least impact on your above roof aesthetics.
73, Jeff Moore -- KE7ACY CN94 On Fri, Mar 18, 2011 at 6:40 AM, zach hillerson [email protected] wrote:
I'm still struggling to figure out the best antenna configuration for me. I was originally planning (and now own) to use a Gulf Alpha dual band fixed at 15* elevation, but I am now having 2nd thoughts. Being limited to 1 roof top tower it might be prudent to get as much use out of the single mast as possible. If I go with 2 horizontally polarized linear antennas on a cross boom(1 ea. 2m and 440) could I use them for both satellites and weak signal work? Is there a downside to proceeding this way?
One concern that I have is that the horizontal antennas seem to have a somewhat limited frequency range, and I'm not sure of the impact. Also, is it prudent to go with separate azimuth and elevation rotators to allow for future expansion (6m etc...), although the separation required between booms is height prohibitive with 6m?
Is anyone running a setup similar to this? Are you happy? Any thoughts, opinions etc... would be appreciated,
Zach N4ERZ
On Mar 18, 2011, at 4:13 PM, Jeff Moore [email protected] wrote:
Horizontally polarized beams will not work very well for satellite use
I disagree, at least for 2m. For several years I've used a 2m7 or cushcraft 10 element horizontal yagi on 2m with fine results. Being horizontal allows me to play on terrestrial as well as meteor scatter where the extra gain from polarity makes a huge difference. Sat links are generally good enough that it doesn't matter much at least on 2m. Obviously there is some compromise in this setup, but it hasn't been a problem yet.
73, Drew KO4MA
+2 with what Drew says. I've been using my M2 2M7 and 420-50-11 like this for years. When I first had them on the roof at my apartment, they were on a single mast, with azimuth only rotation. I had to carefully choose my passes for low elevation so the satellite didn't rise out of the pattern, but they worked fine. Now I have them on a Glen Martin 9' tower mounted on a small Harbor Freight trailer, with a G5400 rotor set, and an unknown manufacturer fiberglass cross-boom. I use a Fox Delta ST2 controller, and SatPC32 running the rotor and my FT-847. I can work the satellites even better, as I now have an SSB Electronic preamp on each antenna. And I still get to do weak-signal work, though not as well, as the antennas are no longer on the roof of a large two-story commercial building. Don't be afraid to try horizontally polarized antennas. Yes, you'll get some fades (sometimes), but if it's what you have, use it. You'll be surprised how well they work, regardless of what some people may say. 73, Jim KQ6EA
On 03/18/2011 08:42 PM, Andrew Glasbrenner wrote:
On Mar 18, 2011, at 4:13 PM, Jeff Moore[email protected] wrote:
Horizontally polarized beams will not work very well for satellite use
I disagree, at least for 2m. For several years I've used a 2m7 or cushcraft 10 element horizontal yagi on 2m with fine results. Being horizontal allows me to play on terrestrial as well as meteor scatter where the extra gain from polarity makes a huge difference. Sat links are generally good enough that it doesn't matter much at least on 2m. Obviously there is some compromise in this setup, but it hasn't been a problem yet.
73, Drew KO4MA _______________________________________________ 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
Like Drew, I've had great results with linear antennas. I use either a linearly-polarized Elk antenna (for portable ops), or a home az/el setup using a 2M7 (vertical) VHF yagi and a 15-el Diamond (horizontal) UHF yagi. Both systems work just fine for me on the FM and SSB sats.
73 de Dave KB5WIA / CM88
On Fri, Mar 18, 2011 at 1:42 PM, Andrew Glasbrenner [email protected] wrote:
On Mar 18, 2011, at 4:13 PM, Jeff Moore [email protected] wrote:
Horizontally polarized beams will not work very well for satellite use
I disagree, at least for 2m. For several years I've used a 2m7 or cushcraft 10 element horizontal yagi on 2m with fine results. Being horizontal allows me to play on terrestrial as well as meteor scatter where the extra gain from polarity makes a huge difference. Sat links are generally good enough that it doesn't matter much at least on 2m. Obviously there is some compromise in this setup, but it hasn't been a problem yet.
73, Drew KO4MA
Hi Jeff, KE7ACY
If the satellite transmit and receive in circular polarization RHCP or LHCP then using horizontal polarization on the ground station is no bad both for the uplink and downlink because you loose only 3 dB in signal strenght but your linear antenna system is not complicated at all.
By the way if the satellite transmit in linear polarization then circular polarization on the ground station is mandatory otherwise receiving with linear polarization when the satellite and the ground polarizations are opposite you loose at list 20 dB into the QSB
Since the most part of actual LEO satellites uses circular polarization both receiving and transmitting then a horizontal polarization at the ground station is fully satisfactory in uplink and downlink for satellite work and as well for weak signal work particularly for a beginner satellite user.
Obviously switching polarization between H-V-RHCP and LHCP for the uplink and for the downlink is much better but it is a lot more complicated.
About the use or not of a elevation rotator with the actual LEO satellites a fixed elevation of 20 degres is a good compromise because when the satellite is overhead the attenuation decreases and the most part of the time in wich a LEO satellite during a pass is above 45 degrees elevation is very small.
73" de
i8CVS Domenico
----- Original Message ----- From: "Jeff Moore" [email protected] To: [email protected] Sent: Friday, March 18, 2011 9:13 PM Subject: [amsat-bb] Re: more antenna discussions....
Horizontally polarized beams will not work very well for satellite use. For maximum utility, I'd get crossed yagis set up to switch between horizontal,vertical, and circular polarization. Use the circular polarity to work the sats, horizontal polarity to do weak signal work, and vertical polarity to pull in those weak repeater and FM simplex signals.
The az/el rotor set up will work best and give you maximum flexibility in your set up with the least impact on your above roof aesthetics.
73, Jeff Moore -- KE7ACY CN94
On Fri, Mar 18, 2011 at 6:40 AM, zach hillerson [email protected] wrote:
I'm still struggling to figure out the best antenna configuration for me. I was originally planning (and now own) to use a Gulf Alpha dual band fixed at 15* elevation, but I am now having 2nd thoughts. Being limited to 1 roof top tower it might be prudent to get as much use out of the single mast as possible. If I go with 2 horizontally polarized linear antennas on a cross boom (1 ea. 2m and 440) could I use them for both satellites and weak signal work? Is there a downside to proceeding this way?
One concern that I have is that the horizontal antennas seem to have a somewhat limited frequency range, and I'm not sure of the impact. Also, is it prudent to go with separate azimuth and elevation rotators to allow for future expansion (6m etc...), although the separation required between booms is height prohibitive with 6m?
Is anyone running a setup similar to this? Are you happy? Any thoughts, opinions etc... would be appreciated,
Zach N4ERZ
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 (6)
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Andrew Glasbrenner -
David Palmer -
i8cvs -
Jeff Moore -
Jim Jerzycke -
zach hillerson