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Level 1

70 points

The great antenna test thread

Since 4.1 has given us back the ability to use Field Test Mode, we can all check the numbers for ourselves. Up until now, I've only seen two sites that were able to do testing with these kinds of results instead of just the 0-5 bars. That isn't much. One reported up to a 24 decibel reduction in signal and the other said 20.

To activate field test mode, on your phone keypad enter:

3001#12345# and press the call button. You'll get an almost blank screen - it has a refresh button which doesn't seem to do anything. The numbers seem to change without doing anything with that button. In a few seconds, your antenna signal bars should turn into negative numbers (bigger negative numbers are worse signal). Here are how the numbers correspond to the bars on the iphones since they adjusted the formula in 4.0.1:

-51 to -76 = 5 bars
-76 to -87 = 4 bars
-87 to -98 = 3 bars
-98 to -107 = 2 bars
-107 to -121 = 1 bar

I believe only the iphone 4 can go that low and still make calls. Older phones can go to -113.

I do not know how quickly the numbers change when the signal changes. I know the bars have a built-in delay so this may as well. Some testing should clarify this.

Now maybe we can get a lot of tests, like this:

1. No case, iphone 4 setting on a table or desk to minimize interference. Write down the number.

2. Pick up the phone and hold it "wrong" (cover both sides of the plastic separator on the left side). Write down the number you get.

3. Put on the case and repeat the above tests.

Keep in mind that the numbers can suddenly change anyway. I don't know all the situations, but, for example, your phone could switch to a different tower. I also read someone say that the kind of network AT&T uses will have sudden fluctuations. I know I've seen the bars change without me doing anything with the phone. Using the field test mode today, I've seen the numbers suddenly jump 10 or more, though most of the time it tends to stay about the same.

So, when testing, multiple tests would be wise to separate the odd ones from what is normal. If you run, say, 5 tests like the first two on the list and usually lose 20 db, but one time you only lose 10 or lose 30 instead, that is probably a change that is in the network and should be discarded.

I'd like to see a lot of people testing to give a better idea of how much of a problem this is and how effective different cases are.

Macbook, Mac OS X (10.6.2)

Posted on Sep 9, 2010 1:53 AM

49 replies

KC7GNM

Level 4

2,904 points

Sep 11, 2010 3:17 PM in response to dbk9999

1. No Case on desk - -85
2. No Case in death grip - -107
3. In Case on desk - -89
4. In Case in death grip - -89

This means that the case does work. I gripped it even harder than in #2 above and could not get the number to drop. Also even with death grip on phone in #2 still at the 1 bar limit just below the 2 bar.

Test confirms that a case does work on the iphone.

dbk9999 Author

Level 1

70 points

Sep 11, 2010 10:09 PM in response to KC7GNM

I went to the Apple store today and got to test some of their phones - I did four of them. All had version 4.1.

What I did was set up the field test mode on each, then laid it on the table and waited a little to be sure the number was stable (at least as stable as these things get - they can still have sudden changes) and wrote down the number.

Then I did the following on each of the four phones, tallying the numbers at each change:

1. Held finger at the connecting point of each phone (not holding the phone).

2. Went back to not touching.

3. Repeated #1.

4. Repeated #2.

5. Held the phone in death grip (though not squeezing hard).

6. Repeat #2.

7. Repeat #5.

8. Repeat #2.

Going back and forth like this, measuring the changes, gave me 4 changes between no touching and lightly bridging the antennas and 4 more between not touching and gripping normally for each of the four phones.

Here are my results, summarized:

Average changes between not holding and lightly bridging the gap on each phone:

17.25
19
15.5
14.25
Overall average = 16.5

Changes when using death grip:

27.5
29
21
17.75
Overall average = 23.81

I was surprised to see some go so high since earlier reports from expert people doing serious testing reported a change of 20-24. That fits in with my overall average though.

KC7GNM

Level 4

2,904 points

Sep 11, 2010 10:42 PM in response to dbk9999

Would have been better if you would have put the db in instead of the change. Not sure what the starting db was so have no reference point. The numbers you have are pretty much impossible to get.

dbk9999 Author

Level 1

70 points

Sep 11, 2010 11:38 PM in response to KC7GNM

I may be wrong, but I don't think the starting numbers matter since what I'm trying to get a handle on is what the common range of change is. Whether it starts at 70 or 80 or 90, does it matter?

Anyway, here are the numbers listed for each phone in this order:

On table
Touching the two antennas
On table
Touching the two antennas
On table
Death grip
On table
Death grip
On table

84, 97, 80, 99, 79, 109, 82, 108, 81

79, 99, 81, 99, 79, 108, 79, 108, 79

84, 95, 86, 103, 78, 102, 81, 102, 84

88, 100, 84, 99, 95, 104, 83, 99, 84

As I've mentioned, sometimes the signal will change even without doing anything, thus the need for multiple tests. Most noteworthy was the second phone, when switching to and from the death grip - big change and absolutely consistent numbers. The ones alternating with lightly touching are almost as consistent.

The other phones had some variation, even when laying on the table (as much as 6 db). My understanding from another poster elsewhere that the ATT system will inherently have such changes.

oxydreNe

Level 1

4 points

Sep 12, 2010 4:52 AM in response to dbk9999

I realized another thing. If even I enable 3G without turning on Celular Data I still get about a -20 dbm lose. =/

I wanna know why because my brothers nokia 5800 have full signal while I only have 2 bars sometimes (-100 I'm getting sometimes)

Anyway, UPS will take it on Monday

Message was edited by: oxydreNe

dbk9999 Author

Level 1

70 points

Sep 12, 2010 2:31 PM in response to oxydreNe

I have no idea.

Does the nokia give numbers or are you going by bars on it?

Because every manufacturer decides how the bars relate to the numbers. For example, 5 bars on the iphone, before they changed the formula on 4.0.1, covered all the way to -91.

Sep 12, 2010 4:04 PM in response to dbk9999

Haha, love the thread!

Ironically, "choking" my iPhone 4 seemed to improve the downstream speed while upstream naturally suffered.

I put this little vid together to show a friend of mine how overblown the antennagate thing was...

http://www.youtube.com/watch?v=1lPX6CPAH7g

4.0.1 definitely made a difference in terms of signal bars in comparison to the 3G iPad--I believe they have not yet updated the iPad to reflect AT&T's preferred algorithm.

viewfly

Level 1

30 points

Sep 12, 2010 6:47 PM in response to dbk9999

I've had the dBm working since the 3G. It carried over to each upgrade (non-JB iPhones, 3GS and now 4). So I've been looking at IP4 dBm's since July.

I've found it does depend where you start. Also, no need to do a unrealistic 'death grip', just a light grip or single finger in the 'sweet spot' will tell you the RF map of the SS band antenna.

1. When starting out at -90dBm or worse, I can hold the phone anyways I wish, with a normal grip and see no effect...as long as I don't touch or bridge the 1mm black gap at the lower left side...as we all know. I can touch just above it, below it, or even place one finger above and another below, with no effect. Likewise touching the other black gaps has not effect in either dB's or data speeds.

But touching/bridging that 1mm black lower left gap will kill my data speeds and/or drop my signal by about 20 dB's, as others have found.

2. However, if I start at -78 dBm or better (-63, -51 dBm, etc), I found touching the lower left black band has NO effect on dBm's or data speeds. I haven't mapped carefully the area between -78 and -90. So it doesn't reduce 20 dBm al all. But from what I see above, -84dBm is still a sensitive signal area. This is the reason why some see no effect and other do not.

Can anyone else confirm this?

What this means for me is in a strong signal area (5 bars, maybe 4) I can hold the phone (normally) without any effect. For weaker signals, I can hold the phone normally, but must be careful not to touch directly the one black lower band. Touching or holding the SS band anywhere else has no effect.

A strong death grip is an unusual grip. I think squeezing that hard compresses your skin, increasing skin density and hence water area on the phone and has some effect....but mostly, the death grip involves strongly pressing part of the hand palm against the lower black band...and that is what kill the signal

dbk9999 Author

Level 1

70 points

Sep 12, 2010 7:42 PM in response to viewfly

If I understand you correctly, when you say you get no change when above -90 as a starting point, you are only measuring grips which do not cross that plastic antenna divider. I haven't even tried testing for those - I was just trying to get a handle on how bad it can get if you do.

Also, by "death grip", I don't mean a strangle hold on it, but just gripping it as some people probably do, with that left corner in the palm, thus touching both antennas. Now, when talking, I don't do that (at least not normally), but I do when using Safari so it hits me on that.

My tests also so a definite difference in effect between just placing a single finger across the plastic divider and wrapping my hand around it as I would do with Safari. One ranged from a change of 14.25 to 19. The other had differences ranging from 17.75 to 29.

Not sure what you mean by the "RF map". I have been informed that field test mode used to let you see more things, but the one in 4.1 just gives you that single number. Perhaps you are seeing something I can't access?

Interesting that at better numbers, you get no negatives een when touching the band. My starting points have never been that good though. I can only test in the stores since I don't have the ip4 anymore. If I ever see a better starting number, I'll watch for that.

One thing for sure, being able to access these numbers reveals a lot more than being limited to the bars would allow!

viewfly

Level 1

30 points

Sep 13, 2010 6:26 AM in response to dbk9999

dbk9999 wrote:
If I understand you correctly, when you say you get no change when above -90 as a starting point, you are only measuring grips which do not cross that plastic antenna divider. I haven't even tried testing for those - I was just trying to get a handle on how bad it can get if you do.

Also, by "death grip", I don't mean a strangle hold on it, but just gripping it as some people probably do, with that left corner in the palm, thus touching both antennas. Now, when talking, I don't do that (at least not normally), but I do when using Safari so it hits me on that.

My tests also so a definite difference in effect between just placing a single finger across the plastic divider and wrapping my hand around it as I would do with Safari. One ranged from a change of 14.25 to 19. The other had differences ranging from 17.75 to 29.

Not sure what you mean by the "RF map". I have been informed that field test mode used to let you see more things, but the one in 4.1 just gives you that single number. Perhaps you are seeing something I can't access?

Interesting that at better numbers, you get no negatives een when touching the band. My starting points have never been that good though. I can only test in the stores since I don't have the ip4 anymore. If I ever see a better starting number, I'll watch for that.

One thing for sure, being able to access these numbers reveals a lot more than being limited to the bars would allow!

I've found that when having a better signal than -90 dBm, you can hold the phone in any manner, death grip or not, single finger on the lower left band...and you will see NO dB attenuation. So yes, it includes grips that bridge the black band. I found signals to go as high a -41dBm in Boston.

The 'death grib' really is just the first way the problem was discovered. As I found, and others before me, the real problem is the little 1mm band on the lower left side. It only takes a single light touch finger, 'bridging' that gap to produce the 'death grip' problem. The left handed (you never see the right handed version) death grip just allows one's palm to bridge that same region. In fact you can place your finger just a few mm' above or below the band...and no effect. As I found, better than -90, and there is no negative effect anywhere...the antenna works fine.

By 'map out' I just mean run your finger along the SS band to see what areas are sensitive. It is only the lower left band; the top black band (near the phone jack) also bridges the two antennas...but unlike the the other...it has no effect whatsoever on the 3G signal/data or Wifi ( a bit of a mystery!). The lower right black band is a 'dummy' it is only cosmetic...beneath it the SS is one continuous piece.

Yes, it is much better that Apple restored the dBm meter.

Sep 13, 2010 11:06 AM in response to dbk9999

The lower left "band" is where the antenna is physically connected to the cellular radio. It's where the radio "squirts" or "pushes" the signal onto the antenna.

I'm curious as to why Apple removed the "Field Test" app in the first place, only to end up adding it back.

Did they know about the larger-than-average signal drop when touched, and removed the app just to see if no one would notice?

Had Apple changed the bar "algorithm" before selling the phones, I don't think people would have known about it. There still would have been a problem with dropped calls and loss of internet connection when touched in weak signal areas, but frustrated customers would not have been able to so confidently blame Apple. Might not have received free cases either.

dbk9999 Author

Level 1

70 points

Sep 13, 2010 11:24 AM in response to viewfly

Well, all I can say is in my tests on four phones at the Apple store, all of which started at better that -90, touching the antenna connecting point on the left caused a noticeable reduction. Holding it with that left corner in the palm caused it to change even more.

Sep 13, 2010 11:48 AM in response to dbk9999

Thanks dbk.....this alone demonstrates why "AntennaGate" was blown waaaaaay out of proportion.......

dbk9999 Author

Level 1

70 points

Sep 13, 2010 12:58 PM in response to lobsterghost1

Well, I think the antenna thing is sort of a big deal but, yeah, not as bad as initial complaints made it out - unless you don't want to use a case on the ip4!

I think they should have realized that putting that sensitive spot where they did was not a good idea and I suspect they could have moved it a little and made it better for at least more people. Maybe can't make it perfect for everyone, but that was almost the worst possible place!

Maybe also put that section under a coating or even part of the case while leaving the rest exposed.

I'm thinking of trying the phone again - get it before the end of sept to be sure I have 30 days and no restocking fee. I can work around any antenna issue, especially since I'll use a case. I'll put the free bumper (arrived just after I returned the other phone) first and then, if all works out, I'll have time to find a better, more protective, case like I have on my 3G.

I just hope the PS issue and bluetooth problems won't hit me again! Can't work around those in any practical sense.

Sep 13, 2010 1:02 PM in response to dbk9999

Well, I think you'll be happy with the phone. I've never had the PS issue and while we've both read that many are not happy with the improvement provided by 4.1, there are just as many who report it's a complete fix for them. And while the antenna was likely not completely thought out in terms of where they placed it, there probably is no other location that would have been better either. With a case (and let's be real, a glass device should be in a case), there really is no antenna issue.

So, I hope you are happier this time around........

The great antenna test thread