[marbletiles]

Regardless of the actual numbers, the issue doesn't appear when the gap in the antenna is taped over or it is otherwise insulated (like with a bumper).

That strongly suggests to me that this is something over and above normal loss of signal caused by picking up in a hand.

[jarek]

Sure -- but I've also seen reports that the effect is much more pronounced in areas of spotty coverage (as measured by bars). Perhaps, even though over and above, the degradation is still acceptable with areas of good coverage.