I had very poor reception for a few years then when FM had almost no reception I started checking it.
I took the antenna off the base and tried a long (3 FT (US) wire in the stud on the base.
Better, but not acceptable.
I pulled the headliner down enough to get the antenna wire off the base and hooked the wire to the cable going to the radio.
It was much better reception and I did tape the wire to the roof for a while.
It was 1 wire from a network patch cable.
I removed the antenna base and opened it, components fell off the board inside, lots of corrosion.
I put a inexpensive antenna booster above the headliner, grounded to the antenna wire, tapped power from the light up there.
Worked great again.
Finally got a new looking base off a totaled VW going to the junk yard.
Radio worked again.
Removed the amp.
Got a power injector from Crutchfield when I replaced the VW radio.