By Cgerlach on Wednesday, October 24, 2001 - 08:42 am: Edit

does anyone know where to find these to mount on vehicles?
Chris

By jay caragay (Jcaragay) on Wednesday, October 24, 2001 - 09:01 am: Edit

Telescoping GPS Antennas?

I'm no expert, but all the GPS antennas were pod-like that were surface mounted - unlike the telescoping antennas for radios.

By Tom P. on Wednesday, October 24, 2001 - 10:02 am: Edit

http://www.gpsaccessories.com/

You can mount these to any thing steel - magnetic mount. So, your roof, roof rack etc. are good places, as are laying it on the dash or mounting it in the alpine window.

Tom Proctor
96 Disco

By p m on Wednesday, October 24, 2001 - 01:42 pm: Edit

Chris, the GPS signal frequency is 1575 MHz, with the wavelength of ~19cm. That means that the antenna need not be much longer than 1/4 of that to be efficient, one reason they don't make them telescopic

peter

By Leslie N. Bright (Leslie) on Wednesday, October 24, 2001 - 03:27 pm: Edit

Chris,

Jay, Tom, and Peter are dead on...

An external GPS antenna is usually housed in a dome or a box, and is of relatively small size.

With survey equipment, we often mount them on the end of a survey rod which can be extended up to 8-foot tall or so, but that's more for ease of handling, and to get it up higher so that nearby houses or bushes won't be in the way, as they would if we just set it on the ground.

IMHO, the 'ideal' place for mounting an external antenna on a Disco would be to mount it on the roof-rack.

FYI... to follow through with Peter's example, 1/4 of 19cm is just under 2"... that's why the antenna is usually housed inside a dome, or in a little arm sticking off of your handheld (or, running down the side of it).

Hope that helps....

-L

By p m on Wednesday, October 24, 2001 - 04:37 pm: Edit

on top of that, the polarization is circular, and the plane of rotation is horizontal. So your antenna can be just flat, made out of self-stick aluminum foil, on top of a layer of paint.

peter