antenna connector?

my question is on my 01 maxima the antenna cable has 2 prongs instead of the normal 1 prong and i want to hook it up to an fm modulator but that has one big prong. i was wondering if they sell connectors that transform the 2 prong antenna cable into the normal 1 prong

Radio Shack?

it can be converted or spliced into .... but I would have to see it in person