i can duplicate your experience Justin...
Latex glove (i actually used nitrile, no diff) = signal problem occured as expected.
Scotch Tape = signal problem occured as expected.
Electrical Tape = signal problem occured as expected.
Griffin case (similar to bumper w/ plastic back) = extremely diminished issues... 5>4, not 5>0 bars.
yes you are right... what i think is happening, im no expert, but since our cell frequencies are really high... the wave of the signal is quite short, thus the antenna is actually using a very small amount of the metal ring.. i believe the signal is being repropigated back into the phone, thus no signal... if the base of the antenna is at the lower left black seperator, than blocking the lower portion of the antenna would cause the most exaggerated results. Probably more exaggerated than we're used to, since were actually TOUCHING the antenna, instead of being separated by a plastic shell.