[amsat-bb] Ground plane vs. Eggbeater vs. best omnidirectional antenna?
ka1rrw at yahoo.com
Mon Feb 11 07:07:13 PST 2008
A Zero Gain antenna is a Zero Gain antenna.
Lets Talk 440 for a second.
A Half wave Vertical is approximately 1.06 feet (0.32
All Half-wave antennas = 0 dBd (or 3 dBi or Salesmans
invented number 6 db)
A Vertical or an Eggbeater style antenna is a good
affordable way to get into Terrestrial and Satellite
operations. However you will be limited to orbits
that are close to your house and times when the
satellite is not too busy with other stations on the
An Eggbeater style may have a slight edge over a
Vertical for high elevation orbits, this is because
the Satellite Antenna polarity may change 4 times
during a single orbit pass.
Example: A few years ago someone did a test and story
about the Shuttles ham signal analysis during a
mission in the 1990s in QST. The shuttle was running
a Vertical antenna on 2-meters. From memory, they
monitored the down link signal and recorded how the
signal dipped 4 times as the polarity of the Shuttle
and Earth antennas became crossed. These dips are
more noticeable if the Earth station is using a Linear
antenna verses a circular polarized antenna.
If you do get bitten by the Satellite bug or want to
extend your terrestrial range, then you need More Gain
(dBds) and coax thicker than 0.405 inches (RG-8
Example: If you switched from a 1 element Vertical to
an 8 element beam, assuming your transmitter put out
50 watts, your ERP would go from 50 Watts ERP to 400
Watts ERP (assuming zero coax loss, and an approximate
9 dBd of antenna gain)
How much power do I need.
Always use the minimum.
73 and have fun WF1F
--- Anthony Monteiro <aa2tx at comcast.net> wrote:
> At 10:26 PM 2/9/2008, Bill Dzurilla wrote:
> >Homebrewed a K5OE Eggbeater II and tried it out
> >but did not notice much, if any, improvement over
> >1/4 wave ground plane I had been using. Both were
> >high, 50' of 9913, no mast-mounted preamp. Can
> >AO-51 OK but can barely hear AO-27 with both
> >Is this as good as it gets with an omnidirectional
> >antenna? Can AO-27 be heard well with the M2
> >eggbeater? With a mast-mounted pre-amp? Is there
> >better omni than the eggbeater?
> >I hear AO-27 much better with an HT and an Arrow.
> >73, Bill NZ5N
Never miss a thing. Make Yahoo your home page.
More information about the AMSAT-BB