GPS External antenna

[Craig]

I have Magellan GPS and want to use it for inside a car, problem being the
car acts as a shield.
I would like to build a rf amplifier, so I can place the antenna outside of
the car.
The antenna on the GPS is sealed so I would most probably have to use a
special type of rf amp.
Any circuit digrams any one knows of.

Thanks Craig

 

[Mike Harding]

I have Magellan GPS and want to use it for inside a car, problem being the
car acts as a shield.

I have a Garmin 12XL which works perfectly proped up
on the dash.

I would like to build a rf amplifier, so I can place the antenna outside of
the car.
The antenna on the GPS is sealed so I would most probably have to use a
special type of rf amp.
Any circuit digrams any one knows of.

At a simple level you can just wrap some turns of wire
around the GPS body close to the internal antenna to
get some coupling from your external antenna.

The following is an excellent GPS site

http://gpsinformation.net/


And this gives some info on making an external antenna

http://www.landyonline.co.za/off_road/gps_antenna.htm


There is also a very active GPS newsgroup:
sci.geo.satellite-nav

Mike Harding

 

[David L. Jones]

I have Magellan GPS and want to use it for inside a car, problem being the
car acts as a shield.
I would like to build a rf amplifier, so I can place the antenna outside of
the car.
The antenna on the GPS is sealed so I would most probably have to use a
special type of rf amp.
Any circuit digrams any one knows of.

Thanks Craig

You should have no problem with the GPSr mounted on the dash.
Occasionally it takes a while to initially lock in, but once it does
you should find that it tracks well.
I know many people who use their Magellans in such a fashion.
I wedge my eTrex at about 45deg between the windscreen and the dash.

Regards
Dave

 

[John Tserkezis]

I have Magellan GPS and want to use it for inside a car, problem being the
car acts as a shield.
I would like to build a rf amplifier, so I can place the antenna outside of
the car.
The antenna on the GPS is sealed so I would most probably have to use a
special type of rf amp.
Any circuit digrams any one knows of.

A warning should go along with any recommended use of a GPS on the dash, as
some vehicles have a metallic layer in the windshield to block UV. It also
blocks GPS signals. An easy way to tell is to look at the satellite lock
screen of your unit (once it has a lock) and move it to behind your windshield.
If you see the signals dropping, you know it's the ones.

As far as external antennas go, if you're lucky enough to have a gps that
accepts an external antenna, you should buy one of those, failing that, you can
buy re-radiating GPS antennas (one end is external, and the other end is placed
in close proximity to your unit within the vehicle).

As far as DIYing, I haven't seen any re-radiating, but normal (not
amplifying) patch antennas yes. A google search should find a few instructions
on building GPS patch antennas.

 

[Mike Harding]

I wedge my eTrex at about 45deg between the windscreen and the dash.

I do the same but have a piece of adhesive velcro stuck
to the top of my GPS and a mating piece on the windscreen,
this keeps it in place on all but the most bumpy of 4WD
tracks and makes it simple to mount the GPS in a hire car
etc without leaving marks.

Mike Harding