Antenna consultants confirm the iPhone 4 problem is what Apple says it is
AntennaSys, a consulting firm, tried the claims on their own, and reached the same conclusion. Holding the iPhone 4 the way it shouldn't be held reduced the bars from five to one, but the call they were on at the moment never dropped. Meanwhile, putting electrical tape on the slit of the metal band actually didn't improve the performance. An urban myth was spreading that the skin short-circuits the antenna parts when the palm is over where they separate.
The engineers confirmed that this human hand interference is pretty normal for phones with internal antennas, but it doesn't usually influence the call itself. AntennaSys plans more thorough testing this week to reach a final verdict.
iPhone 4 Specifications | Review