If Apple is looking for help with their iPhone 4 antennas, they could do worse than call on Anandtech. Faced with ongoing confusion over the signal strength issue, together with Apple's claims that the smartphone has the best antenna performance of an iPhone to-date, they managed to hack their iPhone 4 to show signal strength in dB rather than generic bars.
What the numbers show - that the bars don't - is that the iPhone 4 indicates changes in signal strength differently depending on the overall level of coverage: that is, in an area of generally strong coverage, a drop in dB may not result in any bar indication changes, whereas the same drop in an area of generally low coverage could see all of the bars disappear. Anandtech found that the iPhone 4 does indeed get better reception than the iPhone 3GS in ideal conditions, but that it's also more susceptible to how you hold it; the wrong hold, as we've seen, can slice 24dB off, and make the difference between successful and failed calls.
"The fact of the matter is that either the most sensitive region of the antenna should have an insulative coating, or everyone should use a case. For a company that uses style heavily as a selling point, the latter isn't an option. And the former would require an unprecedented admission of fault on Apple's part." Anandtech
The good news is that, with a case - such as Apple's own Bumper - the iPhone 4 can maintain calls and data connections in poor signal areas where the 3GS would have long lost coverage. Anandtech suggest manufacturers should switch from reporting generic signal strength to indicating signal to noise ratio, a better indicator of whether you'll actually make a call successfully or not; we've a feeling many iPhone 4 owners would be happy if Apple just acknowledged the problem and threw a free Bumper in the box.