Technical explanation on iPhone 4 Antenna issue

Discussion in 'iPhone' started by EEiPhoneFail, Jun 24, 2010.

  1. EEiPhoneFail macrumors newbie

    Jun 24, 2010
    The reason you are dropping calls is due to the fact when you physically make contact with the antenna (any antenna) you disturb or change it's impedance properties. Fluctuating the impedance on an antenna causes signal propagation issues.

    An antenna is essentially analogous to a tuning fork, and when it is vibrating/reverberating any changes to the vibrations (i.e. an impedance fluctuation) will compromise/distort the propagated signal. If this continues long enough the tower you are communicating with will no longer know where you are and say goodbye.

    There is a reason this has never been done before (exposed antenna) it's a very bad design from an RF perspective. It's RF 101, and if you do a little research and take a look at other phones, you will notice that ALL cell phone antennas are galvanically isolated to some extent.

    It is not a firmware issue, it is an inherent design issue, line up and get your rubber bumper.
  2. EstrlM3 macrumors 6502

    Apr 16, 2010
  3. -aggie- macrumors P6


    Jun 19, 2009
    Where bunnies are welcome.
    I’m sure you know more about this than me, but don’t you think Apple’s engineers would know this too?
  4. fizzwinkus macrumors 6502a

    Jan 27, 2008
    Obviously apple has never had to design anything with an antenna before... Nope, can't think of a single thing...
  5. MarkMissoula macrumors member

    Nov 15, 2008
  6. GameraFan macrumors regular

    Feb 5, 2008
    Bumper installed and still seeing drops.

    Phone without bumper lost zero bars in a different area. Seems signal-related to me.
  7. SiskoKid macrumors 6502

    Jul 12, 2008
    Ya, I'm pretty sure a company like Apple would've had some of their designer and engineers take RF 101. I'm sure they probably even graduate RF University.

    My husband has his iPhone 4 already, and I tried to duplicate the issue, and it his phone worked flawlessly. So I'm gonna wait and see what Apple says, but I have a feeling it's probably software related.

    If it's hardware related, then no big deal. I'm sure Apple would replace the phone, so who cares?
  8. frenchie0101 macrumors 6502

    Jul 3, 2009
    No issues at all for me also have the bumper on
  9. EEiPhoneFail thread starter macrumors newbie

    Jun 24, 2010
    If you are closer to a tower than say someone else, then the antenna may be superceded by internal coupling, that is the signal does not need the antenna to communicate, and it may bypass it entirely.

    Also, location information is sent out arbitrarily in packets at random intervals, so it is possible to attempt to replicate this anomaly, and not have the same outcome due to the absence of communication in general.

    A new phone will not rectify the issue, it's an inherent design issue. So a new design would be required to resolve this entirely. Although they can modify/tweak the transceiver firmware to better cope with the impedance fluctuations.
  10. i.phone4 macrumors member

    Jun 15, 2010

    So you're saying there is no way to fix it with software? So this is a fail design, crud, how're they going to fix this?
  11. EEiPhoneFail thread starter macrumors newbie

    Jun 24, 2010
    The defining factor with this issue will heavily rely on demographics. If you live in a major city, with a relatively new tower infrastructure, the effects of the antenna may be negligible enough as to not compromise communication. But if you are living in a smaller demograph, with older infrastructure, this issue may be significant enough to cause periodic (if not complete) disruption in communication.

    For the record I am not trying to bash the iPhone, I own one. I am just dumbfounded as to how they could allow an antenna design such as this to pass a design review. I was anxiously anticipating an iPhone 4 upgrade myself, but this recent influx of issues has put me on the sideline.

    I hope they are able to effectively resolve this issue in a timely fashion.
  12. SiskoKid macrumors 6502

    Jul 12, 2008
    Yes, someone named EEiPhoneFAIL (note the Fail), is an expert on the iPhone design and RF signals.

    Give me a break.
  13. GNice macrumors 6502

    Aug 7, 2007
    I live in a relatively rural area and my iPhone 4 is behaving just like my 3GS. Not making any inferences, but just wanted to add another data point for folks to chew on.
  14. EEiPhoneFail thread starter macrumors newbie

    Jun 24, 2010
    I am by no means an expert on the iPhone design, or RF for that matter. But I am an electrical engineer, who has direct experience in antenna design and testing.
  15. SiskoKid macrumors 6502

    Jul 12, 2008
    Ya, my husband's iPhone 4 and 2 coworkers (one an IT guy who we tried to replicate the issue here at work today and didn't come up) all have perfect iPhones.

    We do live in SF, but my reception on 3GS on AT&T is horrible in this city. And all their iPhone 4s work much better. Even having a finger over the groove.

    So I don't think someone named iPhoneFail is that much of an authority on this issue.

    I understand SOME people are having this problem, but I have no doubt it'll be fixed. It's too much of an oversight of Apple to have such a different design and not test it. No one's that stupid.
  16. TurboSC macrumors 65816


    Aug 4, 2007
    no reception issues here either... maybe if you people would calm down and your hands weren't so sweaty you wouldn't disturb the antenna :p
  17. GamecockMac macrumors 6502a


    Oct 20, 2005
    Columbia, SC
    And I'm sure Apple didn't bother to hire a single person with your background to assist in the design and testing of the iPhone 4.

    Jealous much? :rolleyes:
  18. gceo macrumors 6502a


    Jul 13, 2007
    San Diego, CA
    That was the LEAST TECHNICAL explanation, ever.
  19. Kadman macrumors 65816


    Sep 22, 2007
    This is actually what I (and many others) have been thinking. The people bashing should remove their heads from Steve's a$$ long enough to listen to logic.

    In fact, I did my own test today and found the following:
    1st floor Den: I can touch & bridge the sections with little or no noticeable drop in signal (sometimes drops from 5 to 4 bars but mostly stays at 5). This makes it seem like I'm not having this issue, right? Wrong.

    Basement office: This is a more problematic spot in terms of coverage. With my 3GS I would get 4 bars regularly but sometimes it would reach up into that 5th bar. I tried the "touch test" down there and I can reproduce the video results exactly. I go from 5 bars to none, simply by bridging the metal sections.

    To me this provides some evidence to support (but I'll agree doesn't inconclusively prove) that it's related to normal signal strength from a given location vs degraded signal due to interference caused by bridging the sections.
  20. hackum macrumors regular

    Dec 1, 2009
    Rev. B
  21. w4rmk macrumors regular


    Feb 13, 2006
    I am having the issue on my iPhone 4 here in Denver. When holding the iPhone in my left hand my signal strength goes from 4 bars to dropped call in about 15 seconds. After testing further I find that the join point in the bottom left hand side of the iPhone is the point of failure when skin closes the gap. Holding the phone in my right hand I get a loss of 1-2 bars but the call doesn't drop. I can re-create this every time with identical results.

    At lunch I was out around town and found that if you are close to a cell tower the signal strength is so good that the calls don't get dropped, and if your really close no bars are lost. So the issue gets much worse the further you are away from a tower.
  22. Rodimus Prime macrumors G4

    Rodimus Prime

    Oct 9, 2006
    But apple also has a history of choosing form over funition in its designs. I would not put it past them to do something like this.

    They would rather it look pretty than function well. The iPhone 2g. 3G and 3GS all have been shown to have a crappy antenna design compared to other phones. They choose to make the phone look pretty.
  23. EEiPhoneFail thread starter macrumors newbie

    Jun 24, 2010
    The antenna design is not a matter of opinion, it's a poor RF design. Numerous seasoned RF engineers have commented on this in various articles. I am by no means the lone stance on this topic.

    Like I said before, numerous factors will influence the performance of communication with any phone. And it may become crtitical or non critical. The bottom line is that this IS a poor antenna design, and was implemented to save internal space.

    If you believe Apple RF engineers are so competent. Do some research on the previous iteration's of the iPhone, and you will see why they re-designed the iPhone 4 to have flat surfaces. It is not cosmetically driven, it is due to the fact the curved surfaces (think stealth and reflection of RF energy) are very poor surfaces for coherent signal propagation, curved surfaces induce incoherence/wave collision and poor reception/transmission. Apple screwed up in the RF arena initially, and they are screwing up again.

    They didn't put a gas tank bladder in the Ford Pinto because they saved $1.29 a car, but that didn't stop the numerous rear end collisions and subsequent fires and deaths.
  24. GamecockMac macrumors 6502a


    Oct 20, 2005
    Columbia, SC
    Sure they would. You keep right on believing that fantasy, Sparky. :rolleyes:
  25. thep33t macrumors regular

    Jun 18, 2009
    OP is off slightly, but underlying principle is the same. The antenna will have massive interference from another sourc3e touching it (ie: your sweaty, greasy hands).

    Whether apple took this into account of not is another issue, but I imagine the engineer that brought that up had to go to the end of the lunch line for lowering morale.

Share This Page