The need for them resulted from Apple’s decision to switch to an all-aluminum casing. Radio signals can’t pass through the metal, so Apple broke up the casing with two plastic strips which are transparent to radio signals.
A new patent application published by the US Patent & Trademark Office (via Patently Apple) today reveals Apple’s possible plans to radically change the implementation of antennas in future iPhones and other small form factor devices.
The majority of the patent describes a new composite material made up of a “foam substrate formed of a plurality of foam cells”. However, possible uses for the composite, as detailed in the patent, include a possible new antenna window on mobile devices. This would mark a huge departure from the antenna design in the currently shipping iPhone 4, which still relies on the antenna baked into the stainless steel frame. The same antenna that caused so much controversy regarding reception issues.
Patently Apple explains the potential benefits of the composite: