this is not an automotive mod... with that said, I need to build a signal booster for a car radio antenna.. Not a powered antenna, I have one of those.. I remember in the 80's I could just buy one, but now they seem extinct... could anyone please point me in the right direction to build one of these please.. thank you... its just a small circuit you plug your antenna into and then plug it into the radio... powered antenna do not work the same way for some reason...