Extenral Antenna

[+user13371]

Once in a while I see Gillson and competing antennas on eBay/elsewhere. They're tiny, just a couple inches across, and they weight almost nothing. Indeed, the total weight of the product is given in ounces, and the bulk of that is the cable.

 

With a delivered/resale price in the $20-$30 range, there can't be more than a couple dollars of material in such an antenna.

 

SO... why don't GPS manufacturers build such an antenna into their units?

 

Based on my experience, they already do.

 

Been using GPSRs for a few years; for hiking, biking, and driving. I currently have a Lowrance iFinder H2O, and have previously owned Magellan Merdiians and SporTraks. I could count the number of times I've lost lock on one hand - and those were very extreme conditions. These days I often copy the tracks from my GPS into Google Earth, and it confirms my belief that the built-in antenna is as good as it needs to be.

 

SO... marketing hype aside, who really needs an external antenna? I've only heard two reasonable suggestions:

 

1) Drivers of vehicles with metallized windshields - just so you can put the anteena out of the car.

 

2) Owners of GPSRs with lousy built-in antennas - although as I noted above, I haven't had one of those yet.

 

SO... what antenna do you have, and what GPS are you using it with?

[+Airmapper]

I have the Lowrance AirMap 500, similar to I-finder Pro, excellent patch internal antenna, holds lock well.

 

I use an RAA-3 Remote Amplifying Antenna, I use it in the vehicle, for my attempts to survey, and occasionally under tree cover, although I'm finding the difference is minimal when hunting a cache. I use it sometimes when placing a cache.

 

When I do plug in the external antenna all the bars on the satellite status page take an upward jump, followed by an immediate drop in EPE, usually bottoming out at around 15-18 foot with WAAS. I have had locks inside concrete parking garages with it.

[Neo_Geo]

I'll add a 3rd reason to use an external:

When using it in the cabin of an airliner. It really sucks to have to hold the GPSr up to the window to maintain a lock. So, using a window suction mount, an external antenna allows for greater flexibility in placement of the GPSr within the cabin! With it, I can sit in an aisle seat, place the unit on my tray table, and still get good tracking data.

 

So far I've used it in that capacity with an eMap and a 60C, and it's worked brilliantly every time I've done it. I just got a 60Cx, and will use it (with external antenna) on a plane trip in a couple of weeks.

[planewood]

Take a look at the first and last chart in my post down below. "So ya like numbers......"

 

It shows the two extremes. Under heavy cover without an antenna and under clear skys with an antenna.

 

I use my Gillson all the time. My experience has shown me that the better the reception, the better the accuracy. But, i'm a firm beliver in the democratic process - everyone should make up their own mind!

[peter]

SO... why don't GPS manufacturers build such an antenna into their units?

 

Based on my experience, they already do.

Based on my experience with my Gilsson antenna and my eMaps, I agree with that statement.

 

But it's not very convenient to always have the eMap in an optimum position for best reception. When hiking I get an excellent tracklog while keeping the eMap in my pants pocket since the Gilsson antenna is tucked inside my cap. That's more convenient than having to worry about how the eMap is oriented and whether the internal antenna has a good enough sky-view. Similarly when I'm driving, the internal antenna of the eMap usually works fine, but in marginal reception areas like Yosemite Valley, Manhattan, or the SF financial district it can lose lock due to all the external obstructions combined with that created by the car roof. Putting the Gilsson on top of the roof gives me a much better chance at maintaining a good position lock under those circumstances.

[stevethecache]

Do airlines allow you to use your gps while in flight? that'd be so sweet if they did!

[peter]

Do airlines allow you to use your gps while in flight? that'd be so sweet if they did!

Most do when you're above 10 kft (same as other electronics like laptops), but some do not. There's a list of airlines with their current GPS policies at:

http://gpsinformation.net/airgps/airgps.htm

 

Of course, getting into an argument about it with the cabin crew is never a good idea.

[+budd-rdc]

I'm really curious about this, because on the outside, the size of the antenna between the Garmin 60c and 60cx looks the same, both quadrifilar helix antenna on top of the unit. Yet, they use a different chip (SiRF III for the 60cx) and there's a significant difference in reception.

 

However, I've seen firsthand how the 60c performs much better in a forest with a Gilsson external antenna...

 

I've used many units: Garmin eTrex Summit, Geko 201, Magellan GPS Companion, and Lowrance iFinder GO. For the latter two units, external antenna is not necessary.

[+Skeets_de]

With a delivered/resale price in the $20-$30 range, there can't be more than a couple dollars of material in such an antenna.

 

SO... what antenna do you have, and what GPS are you using it with?

 

Obviously you don't know what's in that blob of of plastic at the end of the cable.

 

It's NOT just a bit of wire. It's actually a helix antenna followed by a very sophisticated low noise amplifier (that's what the power from the GPS is for).

 

Actually you should be amazed that they are as cheap as they are.

 

I have a Gilsson and use it with my Garmin GPS 60cs, and when you connect it you immediately see the difference.

[alpamayo]

With my "old" 60CS the Gilsson antenna was often vital while hiking under tree cover or through canyons.

Now with my new 60CSX, though I carry it along just in case, I actually never felt the need of it and the unit never lost sat reception in such conditions.

[Twilight Error]

I use the antenna while backpacking and mountainbiking. My 76 is in a pouch at my waist, out of the way and the antenna is mounted to the top of either my backpack or camelbak. On the bike, I don't like handlebar mounts because of the potential for crash damage, I feel its much safer in the padded carry pouch I've made. It also allows me to use my external battery without running wires everywhere.

 

The pouch itself is an old camera case that I lined with two layers of metallized bubblewrap. The point was to provide crash protection (beyond the padding in the case) and insulation for winter use. The downside is the metallized insulation completely blocks the signal and requires the use of an external antenna.

[+kb7sei]

I have an H2O as well. I find the internal antenna acceptable, but nowhere near what my Gilsson can do. I get 2-3x more signal, particularly in difficult conditions. Under heavy tree cover the internal can lose signal while the Gilsson can still pull in enough signal for a 30ft EPE. I also get faster locks from a cold start. I like it so much I don't leave home without it. It's velcroed to the top of my H2O and the 3ft wire is coiled and held down on the back of the unit with a little more velcro. It's a nice compact package and it works VERY well.