Sort of, its more of just an electrical contact and the metal sheeting in the cover helps increase the surface area of the antenna.Good luck on the fix. I just noticed that the antenna assembly coming out of the car, looks like it clips in the metal piece attached up at the top of the fin/cover. Is that so? More parts to it than I thought...
From a performance standpoint of car radio antennas (AM/FM reception) it goes: tried and true [albeit ugly] whip, windshield integrated (or aftermarket) screen antenna and following up the rear is the fin style. The reason its so complicated looking in there is signal boosters and attempts to squeeze what should be a several foot-long antenna into an area the size of a soda can, the same reason it gets sub-par reception. The fin style is best left to satellite radio or GPS receivers, in that application they excel.