Think we need some cheering up after all that deep "antenna" tech-talk! LOL
Back to the topic....I can't help feeling that there was the opportunity to minimise the effects of this through more careful design even if the antenna is exposed. I am not sure that an external antenna is a bad thing...and the answer is not coating the metal because the effects of a thin coating will be near zero at these frequencies. But you have to wonder about the positioning of the antenna relative to the frequencies at play and all the things we have talked about above....I just can't help feeling that while it may be hard to cure, it would be fairly easy to minimise....
I assume you have verified this in the same locations giving you problems before. Can you tell us what week of manufacture (from the serial number) that your replacement is?
Think we need some cheering up after all that deep "antenna" tech-talk! LOL
Back to the topic....I can't help feeling that there was the opportunity to minimise the effects of this through more careful design even if the antenna is exposed. I am not sure that an external antenna is a bad thing...and the answer is not coating the metal because the effects of a thin coating will be near zero at these frequencies. But you have to wonder about the positioning of the antenna relative to the frequencies at play and all the things we have talked about above....I just can't help feeling that while it may be hard to cure, it would be fairly easy to minimise....
I think that over all the design has improved reception. Except for when you bridge the gap. It seems like there should have been some way to make bridging the gap harder to do, maybe some sort of non conductive buffer between the two antennas? I don't know I am not an antenna engineer.
I'm not sure there is much that could be done about the issue, given the current design. In order to obey FCC mandates, the antenna must be located the furthest distance from the head i.e. at the bottom - where coincidentally the phone is held. Apple could engineer the "sweet-spot" to be in a different place but it could only ever be at the bottom of the phone where it could potentially come in contact with the user's hand and experience attenuation.
As an aside the previous iphone had the antenna located internally and given it's larger size provided an air gap (within the case) between the antenna and the user's hand. There is no way a sufficiently large gap between antenna and hand could be achieved with the current iPhone without the use of a case.