Engadget has this official statement from Apple on the iPhone 4 reception issue:
Gripping any mobile 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. If you ever experience this on your
iPhone 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.
The key phrase is “if you ever experience this”; most iPhone 4 users seem unaffected by this. Engadget has a video showing the same thing happening with an iPhone 3G from 2008, and Joshua Topolsky admits that in their testing of the iPhone 4, “we had improved reception and fewer dropped calls than we experienced with the last generation, and we never noticed this issue.”
My best guess at this point is that the issue pops up in areas with spotty 3G coverage. With nothing covering the antenna, the improved reception of the iPhone 4 gives you more bars, maybe even up to 5. But when you cover the antenna in these areas with poor coverage, the phone is unable to get a strong signal. I’ve seen several reports from people who can reproduce the problem, but only from certain locations.
★ Friday, 25 June 2010