Quadrifilar vs. Patch antennae

[+The Hornet]

I'm looking to upgrade from my e-trex Summit and one of the many imponderables in getting the "perfect" new unit is the performance of the different antenna types.

 

I find that the patch antenna on my current unit is not particularly good. Living in England a high proportion of caches are hidden in wooded areas and reception is often very difficult. Would a quadrifilar antenna make much difference?

[Eric O'Connor]

Actually, I'd seen many references to how much better the reception was on QH than units with an antenna in the "patch" form factor.

 

My GPS III+ (a unit renouned for it's ability to hold a signal) doesn't seem to fair much better than my Venture.

 

If I'm heading out and am not sure if I'll have time to do a cache I'll grab the Venture, the fact that it's easier to carry makes up for any difference in signal strength. YMMV

[+leatherman]

My friend has a new GPS V. I have a Meridian Platinum. We went on a cache in heavy tree cover. The final location was also in a creek gulley. In the gulley he couldn't get sattilite locks.

My quadrifiliar antenna had three to for sats. Two of them would come and go, but I still had 2D.

 

The GPS V has an external antenna. I've never seen it listed as Quad Helix like the GPS Map76.

 

Preperation, the first law to survival.

[+rdw]

quote:

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Originally posted by leatherman:

The GPS V has an external antenna. I've never seen it listed as Quad Helix like the GPS Map76.

 

---

 

The GPS V has a quad helix antenna. The only GPSRs that have patch antennas are the eTrex line. Everything else is QH. My GPS V has performed very well in bad conditions and acceptably in horrible conditions. Leatherman's story strikes me as being more exception than rule.

 

rdw

[+mikedx]

I am just a beginner but had found the following:

 

I have used a Garmin Etrex and it had problems with satellite reception under moderately dense trees. It kept bouncing around saying here, no 200 feet there, no 50 feet over there, etc.

 

I have used a Magellan 315 for about 12 hunts, and have had NO problems getting a good reception under the same conditions.

[+ApK]

quote:

---

Originally posted by rdw:

 

The GPS V has a quad helix antenna. The only GPSRs that have patch antennas are the eTrex line. Everything else is QH. My GPS V has performed very well in bad conditions and acceptably in horrible conditions. Leatherman's story strikes me as being more exception than rule.

 

rdw

---

 

My eMap also has a patch antenna, and so far it has performed as well or better (in getting a signal) than either our Meridian or our GPS V.

[+leatherman]

quote:

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Originally posted by rdw:

The GPS V has a quad helix antenna. The only GPSRs that have patch antennas

---

 

I'd like to see the referance to the Quad antenna. Where did you find it?

Even Garmin doesn't call it a quad.

 

http://www.garmin.com/products/gps5/spec.html

http://www.gpsinformation.net/gps5/g5review.htm

 

Preperation, the first law to survival.

[+Allen_L]

Like you I couldn't find anything on garmin that told what kind of antenna the V had but lots of places selling it, claim it is a quad helix antenna. Three examples (there are a lot more)

 

http://www.gpscentral.ca/products/garmin/aviationusecomparison.htm

http://www.gps4fun.com/gar_gpsV.html

http://shop.store.yahoo.com/dashack/gargpsvwaase.html

[+leatherman]

quote:

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Originally posted by AllenLacy:

Like you I couldn't find anything on garmin that told what kind of antenna the V had but lots of places selling it, claim it is a quad helix antenna.

---

 

Ok. I think I was just reading the reviews, and the Garmin specs.

THX for the referances.

 

Preperation, the first law to survival.

[+ClayJar]

quote:

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Originally posted by ApK:

My eMap also has a patch antenna, and so far it has performed as well or better (in getting a signal) than either our Meridian or our GPS V.

---

The eMap's patch antenna is (apparently) much more substantial than the eTrex patch antenna. There are still the reception characteristics* to think about, but a substantial patch antenna can get reasonable reception (but the eTrexes don't have a very substantial antenna).

 

*(A quadrifilar antenna has its best reception in the plane perpendicular to its axis -- i.e. hold it pointing up and it'll have its best reception toward the horizon. A patch antenna has its best reception perpendicular to the plane of the antenna -- i.e. hold it with the antenna horizontal, and the best reception will be straight up. In some cases, a patch can be better, but in most, the reception characteristics of a quadrifilar are more appropriate.)

[+niskibum]

Anyone else notice that the Rino has a quad? Or should I say will have a quad?

[+Gimpy]

quote:

---

Originally posted by ApK

 

My eMap also has a patch antenna, and so far it has performed as well or better (in getting a signal) than either our Meridian or our GPS V.

---

 

I too believe that the patch antenna on the eMap is more sensitive than that of the eTrex series. I sold my eTrex Vista, because up here in the NorthEast, I had a heck of a time holding a lock on sats under tree cover. I loved the units size & features, but could not justify keeping it. The eMap seemed to perform better under adverse conditions.A nice feature of the eMap is the ability to add an external antenna if needed. Not an option with the eTrex series. I also really like the fact that with the eMap, memory is not a problem. Like with my Street Pilot, I run off a 64 mb. data card. Holds a whole lot of maps. My Street Pilot, V, III Plus & MAP76 all have the Quad helix design antenna, & all do a far superior job over what the Vista did for me. Just my experience in my little corner of the world.

 

"Gimpy"

[+Gimpy]

quote:

---

Originally posted by ApK

 

My eMap also has a patch antenna, and so far it has performed as well or better (in getting a signal) than either our Meridian or our GPS V.

---

 

I too believe that the patch antenna on the eMap is more sensitive than that of the eTrex series. I sold my eTrex Vista, because up here in the NorthEast, I had a heck of a time holding a lock on sats under tree cover. I loved the units size & features, but could not justify keeping it. The eMap seemed to perform better under adverse conditions.A nice feature of the eMap is the ability to add an external antenna if needed. Not an option with the eTrex series. I also really like the fact that with the eMap, memory is not a problem. Like with my Street Pilot, I run off a 64 mb. data card. Holds a whole lot of maps. My Street Pilot, V, III Plus & MAP76 all have the Quad helix design antenna, & all do a far superior job over what the Vista did for me. Just my experience in my little corner of the world.

 

"Gimpy"

[The Shadows Know]

This is from a May 28, 2002 product review on http://joe.mehaffey.com/ regarding a Magellan GPS with the quad helix antenna.

 

Receiver Accuracy and Sensitivity: [/b]

The Sportrak Pro GPS appears to represent a significant step forward in WAAS enhanced GPS position accuracy. In experiments the Pro was able to achieve 95% confidence accuracy of less than one meter on two out of the three tests we made in the open. It also achieved its specification accuracy of 3 meters 95% of the time under moderate tree cover on all tests. No other consumer handheld GPS we have reviewed has achieved this accuracy.

 

Other tests show that this stationary accuracy is not achieved at the expense of position lag at highway speeds or in overshoot on sharp turns. We consider the Sportrak Pro to be the most accurate consumer GPS receiver that we have reviewed. Magellan Engineers have confirmed that our results are consistent with their data though they do not GUARANTEE accuracy to the level we have experienced in our review unit. Subjective evaluation of the sensitivity would be that it's above average. The most dramatic results of the Pro's performance was under moderate tree cover. Magellan seems to have overcome this general problem with hand-held receivers as can be seen in these plots (HERE)

 

See http://www.gpsinformation.net/mgoldreview/sportrak-pro-rev.html for the entire review and comparison to other GPS units.

 

Quad helix is the only way to go.

[The Shadows Know]

This is from a May 28, 2002 product review on http://joe.mehaffey.com/ regarding a Magellan GPS with the quad helix antenna.

 

Receiver Accuracy and Sensitivity: [/b]

The Sportrak Pro GPS appears to represent a significant step forward in WAAS enhanced GPS position accuracy. In experiments the Pro was able to achieve 95% confidence accuracy of less than one meter on two out of the three tests we made in the open. It also achieved its specification accuracy of 3 meters 95% of the time under moderate tree cover on all tests. No other consumer handheld GPS we have reviewed has achieved this accuracy.

 

Other tests show that this stationary accuracy is not achieved at the expense of position lag at highway speeds or in overshoot on sharp turns. We consider the Sportrak Pro to be the most accurate consumer GPS receiver that we have reviewed. Magellan Engineers have confirmed that our results are consistent with their data though they do not GUARANTEE accuracy to the level we have experienced in our review unit. Subjective evaluation of the sensitivity would be that it's above average. The most dramatic results of the Pro's performance was under moderate tree cover. Magellan seems to have overcome this general problem with hand-held receivers as can be seen in these plots (HERE)

 

See http://www.gpsinformation.net/mgoldreview/sportrak-pro-rev.html for the entire review and comparison to other GPS units.

 

Quad helix is the only way to go.