iPhone 4 Antenna Issues: Let’s Get Some Things Straight.

I’ve steered clear of saying anything to do with the iPhone 4 antenna issue that’s been making the rounds for the past month orso mostly because I believe it’s almost a complete non-story. It seems pretty obvious that they made the choice to put the antenna on the outside for aesthetic reasons (although there’s not a whole lot of other places it could of gone really) and unfortunately the kinds of testing done wouldn’t pick up on this issue. Still there seems to be as many people ready to leap on Apple for any issue as there are lining up to buy their products but those two groups never seemed to have a big cross section as they do today. The problem I have however is not so much whether or not there is a problem, more that a stream of fud has begun to come out of various media outlets and PR firms that confuses the issue at hand rather than solving the problem outright.

For those of you not in the know the iPhone 4 has it’s antenna laid bare to the world in the form of the metal bands that wrap around the outside of the handset. Due to the size constraints of the handset there’s really no where else to put them as the handset is quite thin and the additional electronics that Apple plugged into the new handset doesn’t leave any room for your traditional internal antenna. Like most modern handsets it actually has 3 separate antennas, with one being used for things like Bluetooth/Wireless/GPS and the other two for 2G/3G cellular communications. The separation of the cellular and other antennas is done because the antennas are tuned to a specific range of frequencies and the two cellular antennas are done to improve reception. Realistically the only difference between the iPhone 4’s antenna and any other phone is the fact that you can see and touch it, and that’s where the problems are starting to arise.

You see nearly every phone in the market today has their antennas on the inside of the phone, usually at the bottom of the handset to reduce the radiation levels. They are put inside the handset to make sure that nothing can interfere with them directly like say keys in your pocket or your hand. The iPhone 4’s antenna is completely exposed to the world with those sleek bits of aluminium being electrically conductive. Your hand is also a good conductor and when your hand comes into contact with it you actually form part of a circuit with your phone. This wouldn’t be too much of a problem since electricity takes the path of least resistance (and your hand has a higher resistance than the metal) but the fatal flaw in Apple’s design is the gap that is bridged when the phone is held in the left hand.

When you bridge this gap you are completing a circuit between the two cellular antennas that the phone has. This has the effect of detuning the antennas and significantly reducing their performance and reducing the amount of usable signal available to the phone. This is why the problem can be replicated by both holding it normally or simply bridging the gap between the two antennas. The solution is quite simple the antennas simply need to be isolated from the conductive surface of your hands which is why the bumper cases were so effective in solving the problem.

Jobs has taken the unfortunate route of saying that all phones suffer from this issue and unfortunately that’s just not the case.

Now before any of you go ahead and link me to videos of it happening on other handsets let me explain why that’s not the issue that’s affecting the iPhone 4. You see all phones will suffer attenuation in signal when you put your hands over the top of their antenna. That’s pure physics at work since the signal has to pass through your hand which is actually quite good at absorbing radiation. It then follows that you could “death grip” any phone by just finding where it’s antenna is and covering that place up. Hell check any phone manual and they’ll probably show you where it is and tell you not to cover it up.

However that’s a different problem to the antenna being detuned by you touching it. When your signal drops due to you holding your phone that’s not you detuning your antenna, that’s just the signal being dampened by the barrier of your hand. You can’t detune the antenna when you aren’t able to make electrical contact with it and that’s where those videos that Jobs showed at the press conference were misleading. The problem they have isn’t one of attenuation due to the human hand, it’s one of the antenna being thrown out of whack electrically.

There’s no doubt that Apple handled this badly and in their classic style they’ve attempted to muddle the issue at hand whilst making themselves look like the good guys. Granted their move of giving every iPhone 4 owner a free bumper is a good move and I applaud them for doing so. However their handling of it by trying to bring everyone down and spreading fud about the issue hasn’t done them any favours in my book, nor in anyone else’s as far as I can tell. Hopefully I’ve cleared it up for you so that you understand the difference between the death grip on the iPhone 4 and any other handset out there, rather than the crap that I’ve seen spouted over this issue.

6 Comments

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  1. I was wondering why nobody had mentioned the difference that iphones conductive antenna brings. What I am also serching for months and cant find enough information is the high SAR that this antenna must bring through your body while physically touching it for many hours per day (speaking, surfing the web, playing etc.)

  2. There really isn’t any difference in the specific absorption rate (SAR) between the iPhone 4’s exposed metal antenna and one that’s internal to the phone. The reason behind this is that the SAR is dependent on the field strength, tissue density and tissue conductivity. Having the antenna in contact with the skin whilst forming a circuit and thus detuning the antenna doesn’t have any appreciable affect on those 3 variables.

    The case can be made that when your signal drops your phone responds by upping the power to try and combat it. This is not unique to the iPhone 4 however and should be of little concern to anyone who’s worried about the SAR due to the iPhone 4’s antenna.

  3. Thanks for the interesting discussion. Qualitatively speaking, I always have the feeling that by touching the antenna, a much bigger amount of the emitting power of the phone goes through the body, than by not touching it. Suppose from your answer that there is a difference from e.g. heat transfer.
     

  4. Again the absorption rate isn’t influenced by you touching the antenna past the phone attempting to boost the signal. The feeling you’re getting is most likely your body warming the handset which will also produce a noticeable amount of heat during use. Many people mistake this as the phone’s radiation heating them up (the power of which is too small to do anything) when it is actually the various processors in the phone producing the heat.

    This won’t change the SAR as the energy that you’re now absorbing in your hand is plain old thermal energy, not that due to radio frequencies. There might be an increase in transmission power from the phone due to the lost efficency of the antenna when its heated but apart from that the SAR, for all intents and purposes, remains unchanged.

  5. Of course I didn’t mean that I get phone radiation through heat. I meant that the radiation transfer mechanism could be the same as in heat transfer. Its clear to me now that this is not the case. Many thanks for your replies!

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