Uh... Hate to mention this, but on most devices, those antenna are fake. Cell antennas tend to be coiled, at a specific radius, and to a very specific length. I've owned several different varieties of phones over the years, and with the exception of the very early brick phones all of them with extendable antennas had a plastic antenna that was hollow. I have at least two motorola phones (flip varieties) still around that have the extendable plastic bit that looks like an antenna on it. The real antenna is in the core/cap, coiled around the hole where the plastic bit slides up and down. I actually took a pair of needle nose pliers and clipped the antenna off to show a friend of mine that it was 100% plastic. Nothing conductive at all in there, purely cosmetic. Worse, in most of those early designs, the coils were near the top, near the fake antenna. Meaning it was right next to your head...