Later in the day, Apple acknowledged that holding the iPhone 4 may result in a diminished signal that could make it difficult to make and maintain calls or retain a data connection.
"Gripping any phone will result in some attenuation of its antenna performance with certain places being worse than others depending on the placement of the antennas. This is a fact of life for every wireless phone," Apple said in a statement issued to several media outlets, including PC Magazine , which had run tests earlier Thursday. "If you ever experience this on your Phone 4, avoid gripping it in the lower left corner in a way that covers both sides of the black strip in the metal band, or simply use one of many available cases."
Apple did not reply to a request for comment from Computerworld late Thursday.
Reports began making the rounds on the Web Thursday that the iPhone 4 could lose a signal, or that the signal indicator would show a weakened signal, when the smartphone has gripped in a certain way -- particularly if it was held in the left hand.
Scores of new iPhone owners confirmed the reception problem in a string of more than 360 messages posted to a thread on Apple's iPhone 4 support forum.
"Signal drops from 4-5 bars to 'searching for signal...' when I hold it in my palm or cover up the line on the lower left side of the phone," reported a user identified as "yoshjosh" on the thread. "I understand that cell signals may degrade when you cover up the antenna, but I have never seen anything this severe, and I'm not holding the phone differently than I think most people hold their phones. This is a real issue."
"That's certainly possible," said Aaron Vronko, CEO of Portage, Mich.-based Rapid Repair, a repair shop and do-it-yourself parts supplier for the iPhone, iPod and iPad . Vronko, who regularly takes apart Apple hardware to get an idea of how they're built and their capabilities, completed a teardown of the iPhone 4 by early Thursday, just hours before the smartphone went on sale at Apple's U.S. retail stores.
As Vronko explained it, holding the iPhone 4 in a specific way could disrupt one or more of the two antennas embedded in the steel strip running along the outside edge of the case. "Holding it, especially if your skin was a little bit sweaty, could bridge one or more of the antennas," said Vronko. "That would change the length of the antenna, so it would be tracking a different wavelength than Apple designed it for."
As Apple noted in its statement, the problem could pop up for any cell phone. But Vronko maintained that the iPhone 4 -- which places the two antenna on the outside of the case, as opposed to inside, as was their location in the earlier iPhone 3G and 3GS -- could be especially susceptible to the signal degradation.
"We are, after all, water-filled creatures," said Vronko, "and it's a fact that water affects radio signals. But the length of those antennas has to be a precise to capture the desired band of energy."
The left-handedness of the reception problem also has some foundation in fact. The antenna on the left side of the iPhone handles Wi-Fi and BlueTooth signals, while the one on the right receives cellular signals. Holding the iPhone 4 in the left hand would put more skin -- all four fingers -- in contact with the right side of the case.
Vronko said Rapid Repair is preparing to test the ability of the iPhone 4 to obtain and maintain a cellular signal, and would release its data as soon as it completes its investigation.
After tearing down the iPhone 4 into its component parts, Vronko's impression was mostly favorable. "It's significantly more rigid," he said, referring to the glass back and steel band that replaced plastic components in the previous models. "It should be able to absorb more shock."
But he wasn't ready to say that the new iPhone would be problem free. "I think it will have a less minor damage [to] it over time, but a little more chance of major damage if it's dropped and the glass back breaks."
iPhone 4 sales were brisk Thursday , with long lines at many stores and sellouts at some stores or for some models. For example, a Computerworld editor who had reserved a 32GB iPhone 4 last week before Apple's and AT&T's pre- ordering systems collapsed was offered a 16GB iPhone 4 late Thursday night at his local Apple store after supplies of the $299 model had been exhausted.
That Apple store had sold out its inventory for walk-in customers earlier in the day, and was providing iPhone 4s only to those who had reserved one.
Apple's retail stores are to open at 8 a.m. local time Friday, two hours earlier than usual, to accommodate iPhone 4 purchases. However, as of late Thursday, Apple had not posted any inventory tool on its Web site to tell customers what models, if any, each store would have in stock Friday.
