The stainless steel frame of the Apple iPhone 4, was meant to serve dual purposes.
One - Being the frame to contain the device.
Two - To act as an antenna for signal reception.
However, this steel frame seems to be having some problems in executing, its second duty, of acting as an antenna. It has been noted that when people hold the iPhone 4 in their hands, with their palm around it, touching this steel frame, the signal strength is lost. The bars reduce one-by-one, and sometimes go into a no-signal mode, causing the iPhone 4 to search for signal. But when the mobile phone is left on the table, it recovers and shows the signal bars.
Check out the Youtube video below, which shows how the iPhone 4 loses signal when held in the hand. However, one thing to note here is that plenty of early reviewers have mentioned that the iPhone 4 drops lesser number of calls than the iPhone 3GS. Therefore, as pointed out by Walter Mossberg in his iPhone 4 review, the signal bars displayed on the iPhone 4 screen has nothing to do with making calls. This is a bug which Apple plans to fix.
