For what it's worth on the GPS ground plane issue.......
On all the GPS antenna's I've seen the ground plane is built into the
antenna therefore there is no need for a separate ground plane. If you take
one of them apart you will see the antenna is usually a piece of circuit
board with the antenna and ground plane contained on the circuit board.
Also most of the external antennas are active, meaning they also have a
preamplifier built in for what that's worth....
So the answer is, YOU DON'T NEED ONE.
Gennerally speaking, the only antenna on the plane that you need a ground
plane for is the transponder antenna, assuming you are using the stubb
antenna.
Hope I didn't add to the confusion......
Bill
A010
----- Original Message -----
From: "Jim Brown" <acrojim@cfl.rr.com>
Subject: Re: Europa-List: Ground plane size for GPS antenna
>
> I have been watching this thread on GPS antenna ground plane for several
days. I will share my experience thus far.
>
> I have the Apollo GX 65 GPS which is IFR certified for enroute navigation.
In talking to an electronics installer, he suggested that I simply install
the antenna on a shelf made out of fiberglass behind the baggage compartment
and see what happens. I did just that, and for 500+ hours I have never had a
problem with the signal strength. It has always put me where I needed to be,
when I am on a flight plan.
>
> n3eu@comcast.net wrote:
>
> >
> > >
> > > I have an alternative suggestion.
> > >
> > > With leftover resin and 'bid' make a 4 layup sheet (150mm square
minimum)
> > > with a 25mm flange included on one side (peel ply the outer edge of
the
> > > flange). Include a sheet of tinfoil between the 3rd and 4th layers and
> > > leave a central hole in the 4th layer to enable electrical contact.
> >
> > Before doing all this work, if the GPS receiver has a means to display
signal strength etc., one can temporarily rig a ground plane out of anything
metal and likely see nothing, except for possible minor effects re proximity
to the earth and nearby metal buildings. Ground plane and GPS have to do
with a phenomenon which exists on the ground, not airborne, especially in a
nonmetal airplane. Is it really likely the avionics mfr forgot to mention a
ground plane, but their install manual contains discussion on the more
complex topic of reradiation interference?
> >
> > Regards,
> > Fred F.
> >
>
>
|