Spencer Webb, antenna expert and owner of AntennaSys, speaking with MacRumors:
Ergonomically, the taller phone means the average hand won’t be able to cover both antennas. It’s harder to hold “wrong”. Also, since LTE operates at a lower frequency, 700 MHz, the additional separation is even more valuable.
The aluminum body of the new iPhone 5 will also help the antenna performance, and the hand sensitivity issue will be further diminished. The key word is sensitivity. In other words, changes in performance due to changes in “how you hold it” will be diminished. The antenna will see less change in the “ground mass” of the device.
Everyone remembers the antenna reception problems that plagued the iPhone 4 — the phrases “antennagate” and “you’re holding it wrong” come to mind — but the iPhone 5 design appears to eradicate any of those problems even better than the iPhone 4S.