You can use a wire coat hanger, like when your old style car radio antenna got snapped off and you stuck in an old coat hanger, or better results would be had using thick copper wire or copper central heating tubing, and there is no physical connection between the phone and the antenna feed wire, it just works on close proximity reaction, similar to what you get if you place your hand near to one of the old transistor radio antennas and the signal/audio went up.