There have been lots and lots of discussions, and angry blog posts, about the various problems some users are having with iPhone 4 and signal loss. Apple has suggested that some of the problems are caused by an "improper" grip on the phone. Since both antennas are along the sides of the phone, a hand can actually cause the signal to be lost. The smartest discussion I've seen thus far is this one, from an engineer.
But Apple has posted a letter on their Web site claiming that they used the wrong formula for calculating signal strength bars, and will be changing that in an update in the near future. The update will also be available for iPhone 3GS and iPhone 3G. Apple says this is a problem that goes all the way back to the first generation iPhone.
Here's the heart of Apple's explanation:
Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays 2 more bars than it should for a given signal strength. For example, we sometimes display 4 bars when we should be displaying as few as 2 bars. Users observing a drop of several bars when they grip their iPhone in a certain way are most likely in an area with very weak signal strength, but they don’t know it because we are erroneously displaying 4 or 5 bars. Their big drop in bars is because their high bars were never real in the first place.
To fix this, we are adopting AT&T’s recently recommended formula for calculating how many bars to display for a given signal strength. The real signal strength remains the same, but the iPhone’s bars will report it far more accurately, providing users a much better indication of the reception they will get in a given area. We are also making bars 1, 2 and 3 a bit taller so they will be easier to see.
I'm a little troubled by this explanation, but since I don't (yet) have an iPhone 4.0, I'm in a wait-and-see mode. I note that Apple could have silently provided the new GUI, but is instead being public about their error.
I also note that Apple has recently published a job announcement for 8 WiFi antenna experts. That's far more encouraging.