Does external antenna provide meaningful improvement?

[+gnbrotz]

I'm getting ready to order some cables for my soon to arrive Garmin 76CSx. The same ebay store owner also has external antennas for a reasonable price ($15). The listing claims "high GPS signal amplification" and claims to "Improve GPS satellite signal reception in places where high structures or buildings are experienced".

 

The thing that makes me second guess all this is that it is described as a "patch" antenna. Can this really add performance to a unit with quad-helix SiRF technology? My main purpose in considering this additional antenna is for heavy forest cover or in places where I have a limited horizon, not for in-vehicle use. I'd appreciate any technical insight, as well as your real-world experiences with this type of add-on.

[+Whittling Fisher]

I'm getting ready to order some cables for my soon to arrive Garmin 76CSx. The same ebay store owner also has external antennas for a reasonable price ($15). The listing claims "high GPS signal amplification" and claims to "Improve GPS satellite signal reception in places where high structures or buildings are experienced".

 

The thing that makes me second guess all this is that it is described as a "patch" antenna. Can this really add performance to a unit with quad-helix SiRF technology? My main purpose in considering this additional antenna is for heavy forest cover or in places where I have a limited horizon, not for in-vehicle use. I'd appreciate any technical insight, as well as your real-world experiences with this type of add-on.

 

I haven't had any real experience with the external antennas, but from what I have heard they do not help much with the new 60/76CSx. I have a new 60CSx and it is extremely sensitive and never loses satellite locks in heavy tree cover. I hike in areas with a lot of tree cover and some steep valleys and have not had any problems with it. My old etrex however is a completely different story. I think that the 76CSx would probably act the same as the 60CSx and maintain a strong signal without the need of an external antenna.

[+BlueDeuce]

Good for sub-zero caching. GPS inside the coat, antenna on the outside. Peek at the screen when needed.

[+EScout]

If you place the patch antenna on your car's metal roof (ground plane), then it will perform very well, and better than your antenna in the car. The built-in amplifier overcomes the signal loss in the coax cable. But I do not think you need it unless you have a car/truck with metallic coated windshield/windows that will block your signal (this is not common.) Your GPSr will work fine in the car.

 

However, if you have an extra $15, get it and experiment (also get the cig-lighter power cable because these antennas usually get power from the GPSr and will run down your batteries.)

[+Renegade Knight]

The patch antanea is a perfectly good version. It tends to see straight up better than the quad helix, but since all newer GPSs get better receptions than the older ones, it's got more to do with how the GPS processes the signal than just the type of antanea.

 

You should do fine without an external antanea one. If you find you have difficulty in heavy tree cover...then you can upgrade. If you know you have a vehicle wiht the film in the window that blocks signal and you will use it in the car then as was noted it may be a good idea. I've got a mini van that does that. I just set the GPS by the side window.

[+Thomas D]

Been researching this a bit also... The general feeling seems to be, Yes, it does noticeably help. It will drain your batteries slightly faster... slightly. They are well worth the low cost BUT you will probally get tired of the extra hassle of dealing with it unless you really need it.

 

http://forums.Groundspeak.com/GC/index.php...11&t=125328

 

http://forums.Groundspeak.com/GC/index.php...=144616&hl=

 

http://forums.Groundspeak.com/GC/index.php...=152021&hl=

[appletree]

I use a small external antenna with my Garmin Quest to enable me to record my entire track while hiking. The antenna sits on my hat or the back of my collar and the Quest spends most of the trip in a pocket on my belt, available for reference as needed. I rarely lose signal. I have also used an external antenna with a small re-radiator device with my Garmin Vista in the same way with the same result.

[planewood]

I'm getting ready to order some cables for my soon to arrive Garmin 76CSx. The same ebay store owner also has external antennas for a reasonable price ($15). The listing claims "high GPS signal amplification" and claims to "Improve GPS satellite signal reception in places where high structures or buildings are experienced".

 

The thing that makes me second guess all this is that it is described as a "patch" antenna. Can this really add performance to a unit with quad-helix SiRF technology? My main purpose in considering this additional antenna is for heavy forest cover or in places where I have a limited horizon, not for in-vehicle use. I'd appreciate any technical insight, as well as your real-world experiences with this type of add-on.

My testing has shown that an external antenna definitely improves reception and accuracy especially in areas of tree cover or heavy cloud cover or high humidity.

 

But, get either the Garmin antenna or the Gillson antenna. Do NOT get the other one that is advertised on eBay a lot. Basically a piece of junk that will fail the first time you drop it and the seller will not honor the so-called warranty. Better to get a longer cable and coil up what you don't use.

 

For auto use, you should get a plug in adapter to power the unit. Or, make one like I did. 12V works fine as the Garmins have a voltage regulator inside.

[+embra]

I use a small external antenna with my Garmin Quest to enable me to record my entire track while hiking. The antenna sits on my hat or the back of my collar and the Quest spends most of the trip in a pocket on my belt, available for reference as needed. I rarely lose signal. I have also used an external antenna with a small re-radiator device with my Garmin Vista in the same way with the same result.

My thoughts (devoid of direct experience in this matter) would echo appletree's. Although my GPS seems to maintain a lock hiking under foliage, I usually have it in a pocket or case such that my body is typically blocking signal from some angle and thus the quality of the lock is not so hot. Carrying the thing in my hand helps, but that gets old before long. I've often thought about trying an external antenna perched on a hat as means of reducing self-imposed obstruction. Someday...

[+NightPilot]

An external antenna on your head or somewhere works well. You can use a large washer up there, or a pocket in the hat, or whatever works. You don't get the problem of your body blocking some signals, along with wet leaves, trees, etc, so you will almost always get a better signal.

[appletree]

An external antenna on your head or somewhere works well. You can use a large washer up there, or a pocket in the hat, or whatever works. You don't get the problem of your body blocking some signals, along with wet leaves, trees, etc, so you will almost always get a better signal.

 

No need for a large washer. I use a small, flat steel clip, but I have used a paper clip and an alligator clip as well with good results.

[+NightPilot]

Yeah, whatever works. It depends a lot on the antenna magnet, and the thickness of the hat, as well as the size and composition of the metal inside. Whatever works, and lots of things work. I just happened to have some washers lying around handy.

[Grasscatcher]

Did anyone ever think that "whatever works" might be "nothing additional" ?

Just put the antenna between your cap/hat and the top of your head. Works great and signals aren't blocked.

 

If you MUST attach , or are wearing more substantial headware like a helmet, use a small piece of velcro.

 

The main reason to use an external antenna? It frees up both hands for other uses.

[+PDOP's]

Can this really add performance to a unit with quad-helix SiRF technology?

 

From the comments above I think it's a matter of the external patch antenna having a better view of the sky vs being better than a quad-helix. Also the SiRF technology is the chipset which is a separate issue from the antenna.

 

FWIW I like using an external antenna with my 76C while in a vehicle as the unit doesn't have to be positioned at the windshield and can be passed around if passengers want to have a look.

[planewood]

Everyone needs a walking stick on the trail, right? So, just affix a steel washer to the top of a walking stick. And, if you want, rig up a deal to hold the GPSr at about eye level onto the walking stick. Or, just carry it in your breast pocket.

Edited January 7, 2007 by planewood

[+NightPilot]

Yes, nothing additional can work. There are hats sold with pockets on them which will hold the antenna, or you can just put the antenna inside the hat. That's not optimal, though - I've tried it, and it's a PITA having the antenna slide around over your head. A hat with a pocket may be the best way to go, but it requires buying one, if you don't already have one. If you're cheap, and want the antenna to be somewhat stable, whatever piece of ferrous metal of the approximate size you have handy is by far the easiest. I often use a regular hard hat, which protects my head from briars and branches, and with a washer attached to the top with heavy-duty mounting tape, it also holds the antenna very securely. It may not look supremely cool, but it works.

Edited January 7, 2007 by NightPilot