Is Apple silently fixing the iPhone 4 antenna issue?

July 13, 2010 Hardware — Kyle Wiens

Reports started surfacing today that Apple may have quietly revised the iPhone 4 to add a nonconductive coating to the metal band on the sides of the phone. This would fix the sudden signal drop from electrically bridging the antennas by touching the band in the bottom-left corner with your hand.

We got an independent report of a similarly updated phone from a member of our community, so we decided to investigate. We exchanged one of our units (that had been experiencing unrelated problems with its Bluetooth connection) to see if Apple has changed the manufacturing process since their initial production run.

The serial number on the unit tells you the manufacture date; our original phone was manufactured in mid-June (week 25). The replacement unit we got was made in early-July (week 27), apparently too soon for a manufacturing change.

The serial number also identifies which factory it was made in. (We don’t have a mapping of numbers to physical factories, but we can tell if two phones came from the same plant.) Apple has always done this, and we’ve occasionally had fun comparing Macs to see if they were birthed in the same place. A fun aside: I once had a Mac made in Apple’s Elk Grove, California factory. This information may be useful if Apple is rolling the production change out to their factories one at a time.

The iPhone 4 serial number is easy to decode! It’s in this format:

aa = Factory and Machine ID
b = Year
cc = Production Week
ddd = Unique Identifier
ee = Colour
f = size

Our serial numbers:
85025xxxA4S (16GB unit we took apart)
86025xxxA4T (32GB test unit)
86027xxxA4T (32GB replacement)

Apple has so many iPhones out in the field that it’s very hard to get a feel for what’s going on. They may have just switched to their new process at one of their factories, or they may be rolling it out slowly, or this may be an internet myth. The only way to find out is to check a number of units that have just shipped from the factory.

We need your help! If you got an iPhone in the last few days, check the serial number. If the production week is bigger than 27, try checking the impedance of the metal frame with a multimeter. If you hold the leads about an inch apart, the resistance should be less than one ohm. If it’s substantially higher, you may have a unit with the new coating. (Accuracy of multimeters varies dramatically, but we’d expect a nonconductive coating to have a very high impedance.)

How to measure the resistance of the iPhone 4's metal edge. Our phone reads 0.6 ohms, or eseentially no resistance.


  1. Week 32 iPhone 4
    0.3 ohms

    Comment by filmfrog — August 18, 2010 @ 9:27 pm

  2. 7T033****4S

    i can reproduce the antenna issue, but never goes less than one. and doesnt have the problem often, its pretty rare

    Comment by Montreal — August 19, 2010 @ 7:31 pm

  3. Forget about it:

    Got a T-Mobile Germany 32GB here,production-week 33, death-grip works as expected (going down to 1.5 bars)

    However, since I’m alsways using a case (actually a neat black-only-one from art-wizz), death-grip doesn’t affect the iPhone at all.

    My 2 cents:

    Install Apple’s app “case program” and order your free case, and you’re all set.



    Comment by Gregor — August 26, 2010 @ 9:54 am

  4. Hi ifixit team,

    Have just received my iPhone 4 on Monday 30 August, Serial No 85033—-4T. I measured the resistance as discussed at 1.3 Ohm. My unit does not show any antenna attenuation problems even when the carrier signal is only 1 bar.

    Regards/ George

    Comment by George — August 31, 2010 @ 10:57 am

  5. How much of a different would be required to see. The most recent comment says 1.3 Ohm and the very first one is 0.1 Ohm. Is that considered a large enough difference?

    Comment by Mark — September 1, 2010 @ 9:52 am

  6. Hi!
    I received my Iphone yesterday after I ordered it in the french apple online store.
    I was hoping that it would be a unit with a changed hardware, which it obviously is not.

    It shows a signal drop of almost -20dB (field test mode from ios 4.1)

    Resistance: 0.5 Ohm, wherby I have to say that a 4-wire measurement would be required and the result is very much dependent on the kind of probe you use.
    serial: 84036….

    I’m going to return it next week.

    Comment by Marc — September 11, 2010 @ 9:35 am

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  8. Ok just got my replacement phone in the mail and YES the metal feels slightly different it is not as smooth as my original one and I have them side by side the one I got is 80033xxxxxxx so manufacture week is 33. Ive applied the death grip and although it drops the bars it doesn’t drop a call nor lose the signal completely. On my old one if I give it the death grip with a few seconds it goes to No Signal.

    So I can’t tell you for a 100% Apple has fixed the issue on the newer phones but A. the metal feels slightly rougher and B. the death grip will not drop my calls


    PS I requested the Apple support rep to mail me a replacement phone so there was a $29 shipping cost and they will put a $599 hold on your credit card until they receive your old phone back they will waice the $29 if you have a protection plan but I spoke to the tech at 7pm last night and received the phone 9am so I didnt mind paying the $29

    Comment by Ruben — September 21, 2010 @ 10:42 am

  9. Received my iPhone today: 84035xxxxx (35th week of production).
    Antenna is really conductive… around 1Ohm.

    I did not test the attenuation problem. I just saw that touching the antenna did not alter wifi performance.

    Comment by Hugo — September 21, 2010 @ 2:58 pm

  10. I have checked my Iphone4 which I have ordered it as unlocked from CANADA
    The serial Number is: 85034xxxA4T
    it is still has the antenna when you hold it with death grip, the OHM figure is 0.6 Ω which is means that it is conductive.
    However, everyday use I do not have any issue plus I anyhow use a transparent cover to protect the phone and preserve the look (even if there wasn’t antenna problem I will still use cover)

    Comment by Adil — September 22, 2010 @ 6:11 am

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  13. I just received a Week 37 iPhone 4 today. Measured the impedance and it’s 0 ohms, so there is no new coating to prevent conductance. That said, I have tried the “death grip” over and over and I have seen absolutely no loss in signal by reference to the signal bars.

    Comment by Tookay — September 24, 2010 @ 3:12 am

  14. A friend of mine got an early iPhone 4 and said he could make the bars drop. He later returned the phone due to proximity sensor issues. He recently bought the iPhone 4 again and this time no problems. He is unable to make the bars drop. I talked to a couple of people at my work place with iPhone 4s and they’ve never had any problems. One had gotten his iPhone 4 on release day.

    So I finally jumped on board and got an iPhone 4. I can’t make the bars drop. I watched a YouTube video on how to make the bars drop, and couldn’t do it.

    So I think it was more a quality control issue. A small set of iPhone 4s were just a bit defective coming off the assembly line. The overall design was fine. Apple has probably just improved it’s manufacturing by testing each iPhone for antenna or proximity sensor issues before allowing to pass QA.

    Comment by Wilson — September 25, 2010 @ 6:02 am

  15. One of my friends got an iPhone 4 on launch day in Sydney, I was able to do the death grip thing on his phone.. But another friend received her iPhone 4 2 weeks ago, upon talking about the apparent reception issue I tried to do it on her phone to show her, and to no avail! It dropped 2 bars from full signal and didn’t cut out at all. Even when doing it on a phone call to test it, no drop out from it :)

    Comment by Tom — September 26, 2010 @ 11:30 pm

  16. […] 27  hanno molte probabilità di avere il problema risolto; inoltre sul suo sito-web alla pagina vengono effettuati dei test aggiuntivi come la misurazione della resistenza, essa appare di 0.6 […]

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  18. I had a week 36 phone with full on drop-to-zero reception issues, as verified by my speedtest being unable to ping, download and upload. I had it replaced due to a misaligned back panel (flash and LED didn’t line up) and this one is a week 37 and i can only make it drop one bar, maybe two bars at most with the deathgrip! I can’t cause my calls to drop anymore, where my last one could drop it within 15 seconds of deathgripping. Speedtesting it though, shows that ping is slightly hindered by deathgrip, download speed is unaffected but the grip kills upload speed. How strange.

    Comment by Matt — October 14, 2010 @ 3:18 am

  19. I got mine replaced and the new one was manufactured on the 31st week according to the serial number. The resistence is also close to zero when mesured with a multimeter so I guess no improvement….

    Keep in mind that this is not accurate as a multimeter will mesure the resistance at frequency 0 and the actuall signals being involved in the transmitting/receiving are of a much higher frequency… So the result given by a multimeter is basically useless.
    The only way to really test it would be to hook up the antenna to a network or impedance analyzer.. I do have the necessary equipment at the university where i study but I am not just going to hook up my iphone to machines that will basically inject test signals of unknown amplitude….

    Comment by McFLy — October 14, 2010 @ 3:20 pm

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  21. A friend of mine got a week 43 (end of october) iPhone 4 and it still exhibit the reception issue.

    So still no hardware fix whatsoever and I’m guessing that there will never be any hardware fix on this antenna issue for the iPhone 4, the hardware fix will come with the iPhone 5, nothing before that.

    Comment by bpresles — November 8, 2010 @ 5:53 am

  22. hi i bought my iphone today from the stores in UK and i can confirm it was manufactured on week 48, i have not yet tested it out for the bar dropping which i will do later on and give my result on here, i did have an iphone previously were i had returned it back for the drop calls, wait for my response people.

    Comment by habz — December 7, 2010 @ 11:36 am

  23. i have now tested my iphone 4 which was manufactured on week 48 and can confirm that apple has not changed the hardware at all because i can get the bars drop to 1 bar and this one seems more worse than my previous one.

    Comment by habz — December 8, 2010 @ 1:20 pm

  24. Would you mind telling the version of the firmware and baseband of your week 48 iphone 4? I had one, and I want to do jailbreak. Thx!!

    Comment by Mariel — December 11, 2010 @ 1:19 am

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    Comment by iphone 4 — December 15, 2010 @ 8:15 pm

  26. I have 84023xxxx4s

    I have no signal drop at all. Even i tried for 10 min.

    Comment by jony — December 16, 2010 @ 3:10 pm

  27. in order to get signal drops you must have your iphone 4 on 3g mode, it cannot be on 2g mode or else it wont work.

    Comment by habz — December 17, 2010 @ 2:28 pm

  28. I have an iPhone 4 in the UK, I got last week and it was made on the 50th week.

    I can confirm it does not loose any bars when holding the phone in the bottom left corner.

    79050xxxA4S – iPhone 4 16GB :)

    Comment by Josh Shepherd — January 4, 2011 @ 10:40 am

  29. Also to add the antenna has a different feel to it, it has a matte texture.

    Comment by Josh Shepherd — January 4, 2011 @ 10:41 am

  30. did you have your network on 3g mode because thats the weak signal try it that way, my one was manufactured on the 48 week and i was able to recall the bar drop altough could not completely loose the signal which meant there were some changes made.

    Comment by habz — January 5, 2011 @ 2:29 pm

  31. […] calls.Verizon’s iPhone has a tweaked antenna design.Different network, different antenna. Apple allegedly fixed its Antennagate woes by quietly adding a nonconductive coating to later iPhone 4 models on […]

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  32. Hi, from Spain

    Week 48. The problem is the same, but with another iPhones with diferent weeks >35 no problems in antena but problems in the proximity sensors…

    Bad Job in the plants of production of China. The demand is proporcional this errors… Proximity sensor fails, antena problems, diferent tones of color of the screens, camera flash led problems, …

    Bad Job Steve, this errors are evidents. The iPhone 4 is bad option… In my opinion, tris problems aré intencioned, little. Bugs an problems in a few part of production=very discursions in forums, very free publicity, very applefans waiting the iPhone white or the iPhone 5

    Is evident

    Comment by Alex — January 14, 2011 @ 8:45 pm

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