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GPS antenna?

2006-08-25 19:10:27.095662+00 by Dan Lyke 5 comments

Okay, Eric, I'm doing some mental masturbation on the ultimate bike computer, and wondering what you know about GPS antennas. The devices I'm looking at have an SMA mount and are set up for a passive antenna, although they could be modified for an active one. Power consumption is, however, an issue.

What are the trade-offs?

[ related topics: Maps and Mapping Bicycling ]

comments in ascending chronological order (reverse):

#Comment Re: made: 2006-08-26 18:03:14.290002+00 by: TheSHAD0W

If you're out in the open, even in a wooded area, you shouldn't need an active antenna. If you're between tall buildings, an active antenna might help *a little*. Frankly, I don't think it's worthwhile having one.

#Comment Re: made: 2006-08-26 18:49:36.233467+00 by: Dan Lyke

Yeah, as I look a bit further I'm realizing that I could probably account for 5mA, but not the 35+mA or so that the better antennas want. And the active antennas are heavier.

What I think I really want is a little 6" long whip antenna on the handlebars, but I'm not finding the "here's the part number you want" anywhere.

#Comment Re: made: 2006-08-26 19:34:20.696661+00 by: TheSHAD0W

I don't think whips will work well for GPS. The ones I've seen are little domes. Here's a guide to building one...


And here's the only passive antenna for sale I've been able to find easily:


#Comment Re: made: 2006-08-26 19:48:21.575221+00 by: Dan Lyke

Cool. That ARRL page probably answers most of my questions.

#Comment Re: made: 2006-08-28 03:01:13.120976+00 by: ebradway

Shadow has you working along the right lines. Microwave antennae are "patch" or "dome" style - not whips. The GPS signal is coming pretty much straight down from the heavens. You want a large surface parallel to the surface of the earth. And passive works as well as active, in my experience.