Jim,
The key words here are "noise floor." Omnidirectional antennas can work for satellites when you have a low noise floor and short runs of very good coax (and/or a preamp).
As an example, I've listened for SO-50 a couple of times from here in Washington, DC with my Baofeng UV-3R+ and Nagoya NA-774 telescopic whip. I can hear the satellite a bit, but still quite nosily, above 45 degrees. Back in August, I was in a field in the middle of nowhere and heard it very well from 5-7 degrees above the horizon.
Another example is that some people report decent telemetry success from AO-73 (when in high power mode) using nothing more than 1/4 wave whip. I've never been able to decode a single packet with that type of setup here in the city.
Most people live somewhere between the two extremes I've presented here of "field in the middle of nowhere" and "apartment building in a major urban center" so your mileage may vary. Just keep in mind that in any receiving system, you are looking for an optimal signal to noise ratio. If you have no noise, you don't need much signal and omnidirectional antennas might work fine. If you have a ton of noise, you are going to need a lot of signal from the satellite, which means a beam with decent gain.
73,
Paul, N8HM
On Tue, Mar 15, 2016 at 12:46 PM, Jim Walls jim@k6ccc.org wrote:
I built one about a decade or so ago and was grossly underwhelmed with it. I built it to use for a sat igate. I was able to decode maybe one or two packets per day. Everything else was lost in the noise floor.. Only had about 20 feet of RG-214 cable to the receiver.
Jim - K6CCC
From: "Joe" nss@mwt.net Sent: Tuesday, March 15, 2016 9:37 AM To: "amsat-bb@amsat org" amsat-bb@amsat.org Subject: [amsat-bb] Homebrew Up-Dated Eggbeater Antenna Has anyone built this antenna, and what are your opinions? Meet all the claims being made?
http://wb5rmg.somenet.net/k5oe/Eggbeater_2.html
Joe WB9SBD
Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com _______________________________________________ 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