You know those reception issues iPhone 4 users have been complaining about? Of course you do, it's been the subject of plenty of media attention, including here. But what you didn't know is that it has nothing to do with the antenna at all, but how the iPhone 4 calculates its bars, Apple says.

"To start with, gripping almost any mobile phone in certain ways will reduce its reception by 1 or more bars," Apple wrote in an open letter. "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. This is a far bigger drop than normal, and as a result some have accused the iPhone 4 of having a faulty antenna design.

"We have discovered the cause of this dramatic drop in bars, and it is both simple and surprising."

Hit the jump to find out what Apple says the culprit is, and how it can be fixed.