Detailed Analysis Of iPhone 4 Antenna Issue With iOS 4.0.1 Signal Fix

iPhone 4

Folks at AnandTech had done an excellent analysis of iPhone 4’s new antenna system to investigate the reason for the reception issues reported by many users when they touch iPhone 4’s side antenna bands on the lower left corner.

They have just published a detailed analysis of the iPhone 4 reception issue with iOS 4.0.1 that was released earlier today, which includes the fix to correct the incorrect display of signal strength.

Here are some excerpts from their detailed analysis:

The results are conclusive – Apple has dramatically changed the signal strength to signal bar mapping in iOS 4.0.1 and the iOS 4.1 beta, making the dynamic range not only much broader, but the range values for each bar much wider. The range of signals that correspond to bars three and four are the same width, and bar two is only slightly less.

The cutoff value for two bars to one bar remains the same, but every other value has increased. The result is that the worst case drop of 24 dBm no longer makes all the signal bars disappear, but rather two.

When Apple had released iOS 4.0.1 earlier today, we had mentioned that ever since iPhone 4 was released, users seemed to have forgotten that AT&T has a patchy network, iOS 4.0.1 should bring back the bad memories. AnandTech have confirmed this in their report:

While the software update obviously does not and cannot address the design of the antenna itself – or make the drop from holding the phone any less – it does change the way the issue is perceived among users. The result is that most iPhone users will see fewer bars disappear when they hold the iPhone 4 in a bare hand. The side effect is that the iPhone now displays fewer bars in most places, and users that haven’t been reporting signal in dBm will time see the – perhaps a bit shocking – reality of locations previously denoted as having excellent signal. […]

The reality is that Apple likely wants to deflect at least some of the initial backlash AT&T will face for reporting the signal bars without any concessions. Concessions that used to make coverage look better than it really is. Regardless of how tall the bars are, there are still going to be fewer of them virtually everywhere. Interestingly enough, while bars 1 and 2 are the most changed, their respective cutoffs are virtually unchanged.

AnandTech observed the following three things about iPhone 4’s antenna when they compared it with iPhone 3GS on iOS 4.0.1:

  • Reception in average conditions is sometimes significantly better on the iPhone 4 than on the 3GS.

  • Signal strength is sometimes the same as or worse than the iPhone 3GS.

  • The iPhone 4 is better at holding onto calls and data at very low signal levels.

AnandTech concludes:

The new signal strength visualization in iOS 4.0.1 is simply going to be more honest with iPhone users. Whether that's going to result in customers confused about why their phone performs "worse" after the update or simply get really mad at AT&T remains to be seen.

While the iPhone 4’s antenna tradeoff is largely acceptable if you live in an area with good reception, if you don’t then it quickly becomes a problem.

Whether or not the antenna design manifests itself as an issue really depends on AT&T’s coverage where you’re using the phone. As a result, AT&T can also share in the blame here.

Our original assessment still stands: Apple should provide free bumpers to iPhone 4 customers.

You can read AnandTech’s analysis of iOS 4.0.1 signal fix and iPhone 4 antenna problem here.

Please don’t forget to drop us a line in the comments to tell us your experience with iPhone’s reception after upgrading to iOS 4.0.1.