GPS antenna questions.

I'm new to GPS and recently bought a WorldNavigtor 3100. So please forgive
the stupid questions.

I am interested in the idea of using an external antenna (or at least an
antenna that is detached from the unit) -- not just for the WorldNav but for
other GPS's too. Here are my thoughts and questions:

Are the "antenna" and the GPS sensor unit 2 different things? On the
WorldNav there is an approx. 1"-by-1" square that gets flipped up to face
the sky. It looks like a small solar panel (which I know it isn't). So, is
that the GPS sensor that gets the signal? If I wanted an external or remote
antenna, would the antenna that "sees" the satellites contain a GPS sensor?

Do any GPS's come with a detachable sensor or antenna where, if I wanted to,
I could place the sensor or antenna on the dashboard and keep the unit
itself down low on a car seat or wherever (in a location where it would not
ordinarily be able to receive a satellite signal)? If so, any suggestions
of models that do that? What I would specifically like to be able to do is
create a location to place the GPS unit that is not on the dashboard and the
antenna or sensor on top of the dash or elsewhere.

Another thing I would like to be able to do is have a permanently mounted
and internally-wired external antenna (or sensor?), and be able to just plug
the GPS into a power source and plug the antenna into the GPS when I want to
use it. I am thinking of this for a commercial vehicle. Any ideas on doing
that or where to get more information about that type of setup?

Thanks. Any thoughts or suggestions would be welcomed.

BETA-32 wrote:

I'm not familiar with that particular model, but it sounds like it uses
a "patch" type of GPS antenna located in that square piece. That would
just receive the microwave signals from the satellites and pass them
along to the radio receiver circuits inside the main box.

Yes, some models have a connector for attachment of an external antenna
- usually either a BNC or an MCX connector. A number of Garmin models
have such connectors and also some from other makes such as Magellan
and Lowrance.


If yours doesn't have a connector for an external antenna, you can
still use a "re-radiating" antenna. These units include an amplifier
and a second antenna that you place close to the internal antenna on
your receiver. See
http://www.pc-mobile.net/gpsant.htm for one example that's
battery-powered and there are various makes that take 12 VDC vehicle
power.

Thanks. I'm checking out the link for patch type antennas and will look for
other similar websites.

BETA-2K wrote:
connector for attaching an external antenna. To find out which
antennas would be compatible you need to find out what type of
connector it has and also whether it supplies a voltage for powering
the external antenna on that connector. Many external antennas include
a small amplifier and therefore need to be powered by the GPS receiver.
www.gpsgeek.com is a good source for external antennas that work with
Garmin and Magellan units that have BNC or MCX powered connectors. But
you need to find the specs for the connector on your WorldNavigator to
see if they'd be compatible.

BTW, most external antennas are of the patch type, but another syle
such as quad-helix would work as well - it wouldn't have to be the same
type as what your receiver has internally.

posted on 19 Nov 2006 07:36:43 -0800, peter wrote: Begin


I have an older external quadrifilar helix magnet base antenna with the
BNC connector that I have to adapt to and can't find any reference to it
anywhere. It's about six inches tall, about one inch in diameter and the
base is about two and a half inches diameter, I don't have it in front
of me now to give more precise figures, does anyone happen to remember
the model number for it?
I think it used to be the only external antenna Garmin offered back when
the 45 and 12xl were in their heyday.
BTW: It works very well with the 76CS

--

Bart