Trying to get back into satellite radio from the early 2000s, I wonder what happened to circular helical antennas. Are they out of fashion now?
73,
Jerry AB5R
EM12kh
My experience with the M2 eggbeaters left something to be desired. The 70cm antenna was deaf without a gasfet preamp. I use the 2m one as my local repeater and simplex antenna now.
I've read other comments here about limitations, but I'm still not convinced circulars are a bad thing.
That's about all the advice I can render.
73 Dave N4CVX
Sent from my iPad
On Aug 12, 2016, at 13:40, Gerald Payton gp_ab5r@outlook.com wrote:
Trying to get back into satellite radio from the early 2000s, I wonder what happened to circular helical antennas. Are they out of fashion now?
73,
Jerry AB5R
EM12kh _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Noting wrong with "circulars". Whats wrong is expecting to hear a weak signal on the horizon using no gain.
Eggbeaters are great antennas that give good circular polarization at all elevation angles to cover the whole sky and are great for non-tracking ground stations listening to strong signals from space (the ISS for example). But by definition, you cannot hear "all of space above the horizon" without giving up gain everywhere.
Space tracking satellites is not homogeneous. You need TEN times the gain down near the horizon compared to overhead. Any antenna designed to hear everywhere upwards equally is going to be ten times worse on the horizon where it needs gain the most. And satellites spend more than 70% of their time below something like 22 degrees.
Please see: http://aprs.org/LEO-tracking.html
Bob, WB4APR
On Fri, Aug 12, 2016 at 5:14 PM, Dave Mann cwo4mann@comcast.net wrote:
My experience with the M2 eggbeaters left something to be desired. The 70cm antenna was deaf without a gasfet preamp. I use the 2m one as my local repeater and simplex antenna now.
I've read other comments here about limitations, but I'm still not convinced circulars are a bad thing.
That's about all the advice I can render.
73 Dave N4CVX
Sent from my iPad
On Aug 12, 2016, at 13:40, Gerald Payton gp_ab5r@outlook.com wrote:
Trying to get back into satellite radio from the early 2000s, I wonder
what happened to circular helical antennas. Are they out of fashion now?
73,
Jerry AB5R
EM12kh _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
We used the M2 eggbeaters as our back up ARISS antenna system; because of a technical issue at the last minute we actually ended up doing the ISS QSO on the eggbeaters vs. the tracking yagi with polarization switching, phew! With 600 some odd kids sitting behind us when the astronaut answered we were pretty relieved. Probably knocked a minute or so off the Q&A period but the audience never knew the difference. Talk about sweating bullets for a few moments!
73 - Dino KL0S
On Aug132016, at 1249 PM, Robert Bruninga bruninga@usna.edu wrote:
Noting wrong with "circulars". Whats wrong is expecting to hear a weak signal on the horizon using no gain.
Eggbeaters are great antennas that give good circular polarization at all elevation angles to cover the whole sky and are great for non-tracking ground stations listening to strong signals from space (the ISS for example). But by definition, you cannot hear "all of space above the horizon" without giving up gain everywhere.
Space tracking satellites is not homogeneous. You need TEN times the gain down near the horizon compared to overhead. Any antenna designed to hear everywhere upwards equally is going to be ten times worse on the horizon where it needs gain the most. And satellites spend more than 70% of their time below something like 22 degrees.
Please see: http://aprs.org/LEO-tracking.html
Bob, WB4APR
On Fri, Aug 12, 2016 at 5:14 PM, Dave Mann cwo4mann@comcast.net wrote:
My experience with the M2 eggbeaters left something to be desired. The 70cm antenna was deaf without a gasfet preamp. I use the 2m one as my local repeater and simplex antenna now.
I've read other comments here about limitations, but I'm still not convinced circulars are a bad thing.
That's about all the advice I can render.
73 Dave N4CVX
Sent from my iPad
On Aug 12, 2016, at 13:40, Gerald Payton gp_ab5r@outlook.com wrote:
Trying to get back into satellite radio from the early 2000s, I wonder
what happened to circular helical antennas. Are they out of fashion now?
73,
Jerry AB5R
EM12kh _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Hi, Jerry
I'm guessing here that you mean the "bed spring on a stick" kind of normal-mode helix antenna that you point at the bird, rather than some other *omnidirectional* helical antenna like a Quadrifilar Helix Antenna, aka "QHA"
Well, I'm not really sure if they were ever "in fashion". They're pretty easy to build, pretty broadbanded, and are quite forgiving of minor errors in construction, but seeing as they have no way to switch polarization, which can be pretty handy at times, they're pretty limited.
I've built a couple, one for 1.2GHz, and another for 70cm, and they work quite well for being so simple.
One for 2 Meters is quite a bit bigger, and they start to get cumbersome to rotate.
Other than the two I built, I've never seen an Amateur Radio version "in the wild", although I have seen numerous ones for commercial and military use.
73, Jim KQ6EA
On 08/12/2016 06:40 PM, Gerald Payton wrote:
Trying to get back into satellite radio from the early 2000s, I wonder what happened to circular helical antennas. Are they out of fashion now?
73,
Jerry AB5R
EM12kh _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (5)
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Dave Mann -
Dino Papas -
Gerald Payton -
Jim Jerzycke -
Robert Bruninga