Poking holes in Apple's iPhone 4 antenna explanation

Saying it was "stunned" by its mistake, the company will issue a software update to fix how it calculates signal strength on its iPhones. So does that settle things, really?

Marguerite Reardon Former senior reporter
Marguerite Reardon started as a CNET News reporter in 2004, covering cellphone services, broadband, citywide Wi-Fi, the Net neutrality debate and the consolidation of the phone companies.
Marguerite Reardon
6 min read

Apple has said that users have to hold the iPhone 4 the right way to get the best reception. Now it also says it has a software fix for signal issues. Josh Lowensohn/CNET

Apple now blames reception issuesthat many new iPhone 4 customers are experiencing on a software miscalculation rather than on hardware design. But will a software update really fix the problems that many customers are reporting?

I'm not sure I am buying Apple's explanation.

Since the iPhone 4 launched last week, thousands of consumers have complained that when gripping the phone around the lower left-hand corner of the device, the signal degrades or calls are dropped. Apple acknowledged the problem, and explained that customers were simply covering up the antenna with their hand. CEO Steve Jobs told consumers the best way to fix the issue is to hold the phone differently. His other piece of advice: Buy a $29 rubber bumper to put around the phone so you don't cover up the antenna.

Now the company says its engineers have made a "stunning" discovery. People may be finding that their reception is poor and that calls are being dropped not only because they're holding the phone wrong, but also because they think they have a better signal than they actually do. In the statement, Apple says that it had made a mistake in the formula that calculates the number of bars that display the signal strength on all of its iPhones.

"We were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong," it said in a statement. "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."

"We were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong."

Apple said that a fix, which will correct the issue not just for iPhone 4 phones, but also 3GS and 3G iPhones, will be available within a few weeks.

But hold on a second. How exactly will this ensure that the new iPhone 4 doesn't drop a call? The answer is that it probably won't.

"If the only thing that Apple is changing in this software fix is how the bars are calculated, then this is simply a pacifier for people who like to watch bars," said Spencer Webb, president of AntennaSys, an antenna design firm. "And signal 'bar watching' is a dangerous way to draw technical conclusions about a phone's reception."

Indeed, the bars that one sees displayed on any cell phone can be misleading. This is not just an issue for the iPhone, but for all cell phones, Webb explains.

Cell phones are usually within range of multiple cell sites. Cell towers in these areas are constantly pinging devices and handing off signals. So it's difficult to truly assess the strength of a signal simply from the bars displayed on the phone. There are also other issues to consider when talking about reception, such as how crowded the network is.

Any of these factors can cause a call to be dropped. And when customers are talking about low signal strength and poor reception, dropped calls is what they are really talking about. If the signal is weak and the call stays connected, no one cares or notices (except that a weak signal will also run down the battery on the phone faster).

Customers look to the bars on their phone to help them gauge the likelihood that they can make the call and keep the call going.

So Apple's explanation--that it is changing the way it calculates the bars--is somewhat misleading. If calls are being dropped, then rejiggering the calculations for the display will not change the outcome of that event.

The crux of the matter
This leads us to the real problem, which is that the iPhone 4 may be more sensitive to antenna disruption than other phones.

Apple has acknowledged that covering the little line on the outside of the iPhone 4 can disrupt calls. Numerous tests have been done, and here at CNET we've replicated the results of these tests.

In Apple's defense, covering up the antenna of any cellular device could degrade the quality of the signal and ultimately lead to dropped calls. In the olden days, when people walked around with big brick phones, the antennas stuck out of the top. Even early flip phones had antennas that could slide up. As aesthetic tastes have changed, antennas have disappeared from view.

"If the only thing that Apple is changing in this software fix is how the bars are calculated than this simply a pacifier for people who like to watch bars."
--Spencer Webb, president, AntennaSys

But cell phones are wireless devices, and all wireless devices need antennas. The problem with making the devices slick and cool-looking is that people don't know where the antenna is, and they inadvertently cover them up.

Apple itself has tried to explain this fact. But it also acknowledged that some users are complaining that the iPhone is more sensitive to antenna's being blocked than other devices.

"To start with, gripping almost any mobile phone in certain ways will reduce its reception by 1 or more bars. This is true of iPhone 4, iPhone 3GS, as well as many Droid, Nokia and RIM phones. But some users have reported that iPhone 4 can drop 4 or 5 bars when tightly held in a way which covers the black strip in the lower left corner of the metal band," the company says in the statement. "This is a far bigger drop than normal, and as a result some have accused the iPhone 4 of having a faulty antenna design."

Webb believes that Apple is right to inform customers that they should avoid holding their phones in such a way as to block the antenna.

"This design appears to be more sensitive to the human hand contact than other designs," he said. "But I wouldn't necessarily call this a design flaw. Apple went for a cool design to get the phone as thin as possible. And they took a risk. But it's not something that can't be easily dealt with."

Some testing of the iPhone 4 even suggests that the new antenna has actually improved reception of the device over previous versions of the device. The Web site AnandTech tested the iPhone 4 and the Google Android Nexus One as they were held in different positions: gripping it tightly, holding it with an open palm, resting it on a table, and so on.

What the testers found is that each of the phones exhibited some attenuation when in different positions. But it appears the iPhone was more sensitive and signal strength varied more than other phones when held in different positions.

What's interesting about the results of these tests is that the iPhone 4 actually performed better in low-signal situations than either the Nexus One or the iPhone 3GS. But connectivity is affected when the phone is held in different positions.

"I can honestly say that I've never held onto so many calls and data simultaneously on 1 bar at -113 dBm as I have with the iPhone 4, so it's readily apparent that the new baseband hardware is much more sensitive compared to what was in the 3GS," AnandTech says in its blog. "The difference is that reception is massively better on the iPhone 4 in actual use."

So what does this mean for iPhone 4 customers? Steve Jobs original advice still stands. Just hold the phone differently. The software upgrade won't likely fix the problem. But not covering up the antenna will.