iPhone 4 Signal Problem Verified

Written by Clive Webster

July 2, 2010 // 10:15 a.m.

Tags: #4 #antenna #apple #drops #flaw #ifail #ios-4 #iphone #iphone-4 #issue #low #macalyte #poor #problem #reception #signal

The internet is ablaze with stories that the new iPhone 4 has (or has not) got a significant problem with its antenna. Ars Technica reports that the iPhone 4 drops signal reception when the left and bottom antennas are bridged by a finger.

However, all the evidence has been anecdotal to date with some people reporting significant problems and others not experiencing an issue at all. The clever chaps over at AnandTech have found a way to quantitatively test for the problem and have come up with a load of numbers and graphs to show that the problem is real. The testing also reveals what the two antenna are for, and how Apple could have prevented the problem in the first place.

The cause of the problem is the iPhone 4’s layout of its two antennae. They’re the stainless steel bands that wrap around the edge of the handset, with one for Bluetooth, Wi-Fi and GPS and the other for UMTS and GSM (telephony data standards). By placing a sweaty finger across the thin gap between the two antennae, you bridge them, thus introducing ‘attentuation and detuning’, which drops your signal strength.

AnandTech says that the problem could have been avoided had Apple used ‘an insulative coating atop the stainless steel. Perhaps even use[d] diamond vapor deposition (like they did with the glass screen atop the iPhone 3GS) to insulate the stainless steel from users.

The really clever bit about AnandTech’s testing is that it managed to find a way to circumvent the bars system that the iPhone (and every other phones) uses to represent signal strength and instead used actual signal strength figures in dB. It was a fairly convoluted process to enable this, as Apple has removed the usual method (the Field Test monitoring problem) from iOS 4. ‘Unfortunately, like iOS 4 running on the 3GS and 3G, Field Test is absent from the iPhone 4. It isn't a matter of the dialer code, it's that Field Test has been completely removed from the applications directory in the filesystem… For whatever reason, Apple really doesn't want anyone running that tool anymore.

AnandTech does say that the iPhone 4 works acceptably well at a signal strength of two bars, and that using a thin case ‘the signal strength drop from holding the device is on par if not better than other phones.’ It also concludes that ‘the iPhone 4 performs much better than the 3GS in situations where signal is very low, at -113 dBm (1 bar)’.

It seems the furore that iPhone 4’s antenna is a case of much ado about nothing. Where have we seen that before? Post your favourites in the forums.

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