Patch Antenna V Quad Helix

[zcoyote12]

I noticed the etrex legend has a patch antenna and the 60C has the quad helix. What is the difference and is one more accurate than the other?

[+Airmapper]

I have two GPS units, one has a pach, the other has quad helix. I don't notice much difference in accuracy, but it might differ a little. With a quad helix you have to hold the unit so the antenna pionts straight up to get a better signal. The pach isn't quite as picky, but you do need to hold it so it faces the sky.

I did a side by side test of my two units, not much difference, my Airmap did a little better because I had an amplifying antenna on it but both did well.

[peter]

Both designs can work very well and both can be executed poorly, so the quality of the particular antenna is more important than the type. A practical difference is that the patch antenna is most sensitive in the direction above the flat surface of the patch while the helix antenna is most sensitive in the direction along the axis. So the 60c will work best when held nearly vertical and the Legend will work best when almost flat. But the reception patterns of both a very broad, so exact orientation isn't critical. Usually the reception of the patch type falls off a bit more rapidly for signals coming in at large angles (i.e. near the horizon when the antenna is oriented properly). That can result in slightly worse reception when those signals are also passing through dense foliage, but it also reduces the susceptibility to false multi-path signals that can otherwise reduce accuracy.

 

But in practice I've noticed very little consistent difference between the models I have with patch vs. helix antennas other than the preferred orientation.

[+IVxIV]

I noticed the etrex legend has a patch antenna and the 60C has the quad helix.  What is the difference and is one more accurate than the other?

That specific combo is an unfair test to compare. The black&white eTrex's patch antenna is an old design, and has been reported countless times for causing frustration, losing sigal expecially under tree cover. That and, it is extremely sensitive to how it's being held.

 

If you really want to compare apples-to-apples, use either an iFinder or Explorist as an example of what a MODERN patch antenna is capable of. Even a newer eTrex (a color Legend or color Vista) is vastly superior to it's older B&W ancestors.

[Neo_Geo]

The difference is noticeable in thick foliage - the unit with the quad helix would maintain a lock better than the Legend in the woods. The new color eTrex models (LegendC and VistaC) have the patch antenna, but they seem to do better than units that have a quad helix.

[zcoyote12]

I am looking at either the 60C or Etrex legend C. I like the small size of the legend C since it will be in my pack durng hunting outings and not used that much. But I do not want to sacrifice performace for size. In checking out the specs there is not a lot of difference except antenna and storage capacity.

[peter]

Additional differences are the 60 series support of external antennas and an RS-232 compatible port which means they can be used with devices that require NMEA messages like chartplotters, radar units, auto-pilots, and GPS-compatible EPIRBs and VHF radios.

 

Whether those matter to you depends on your applications.

[+EScout]

I think the better question than accuracy is the ability to get signals and keep a position fix. The sensitivity of the radio receiver and the quality of the signal processing is more important than type of antenna in a handheld. The most recent models such as the eXplorists with patch antennas have excellent reception. With the trend to smaller models, most future units will probably have patch antennas.

[zcoyote12]

Good point. Nicxely put.

[+Renegade Knight]

Good point. Nicxely put.

Before all the new GPSs came out it was fairly cut and dry what the differences were. AFter the new ones came out and the patch antaneas improved their reception over the older ones it wasn't cut and dry.

 

In the old GPSs quad helix worked better under tree cover than patch and patch better in canyones, near rock faces (urban jungle as well) than a quad. However it wasn't by a large margin either way. It still wasn't cut and dry then. Quad over patch in tree cover by a small margin but an external antanea was the way to drastily improve reception under the trees. The funny thing was even though the quad had the edge the external antaneas were patch.

 

Improvemetns made to both have made both perform better.

[+jwahl]

While mostly an experience thing, I have two receivers that are pretty much the same except for the antenna. The GPS48 has a vertically rotatable quad-helix. The other is a GSP12CX that has a patch antenna. I find that in any given situation one does better than the other, but can find no real correlation with that and what is happening. For example, in the woods sometimes the 48 does better, sometimes the 12CX does better. They both seem to do about as well or slightly better than the 60C. The GPS76 is supposed to have a helix, but it seems like it must be horizontal and it never seemed to be as sensitive as my older Garmins.

 

- jlw

[Prof. Y. Lupardi]

I think the better question than accuracy is the ability to get signals and keep a position fix.  The sensitivity of the radio receiver and the quality of the signal processing is more important than type of antenna in a handheld.  The most recent models such as the eXplorists with patch antennas have excellent reception.  With the trend to smaller models, most future units will probably have patch antennas.

I do fully agree with this. In my opinion the helix <-> patch is for the most part an advertising gimmick.

When Garmin switches over from its own chipset to the SiRF III you will see a much better signal reception. Then the question of who is better: patch or helix is moot..