Who remembers the time little stickers with a 'gold printed circuit' were touted as being range extenders/boosters for mobile phones?  Turned out to be more useless than a dunny roll wrapped in tin foil 

I now see they are promoting external antenna for phones that plug into the ear-phone socket … THIS sort of thing.

Has anyone tested or used such a thing?  Is using the ear-phone socket gonna work?  For $4 I might try it