Why some cars have antennas and some doesn’t, and what the “fin” looking like is doing?

Question

I see some cars have antennas (and some even have two) and some doesn’t.
Why is that? And why some have one or two what’s the matter with the count? And wha the matter with their length and the direction they are pointing?

And what’s the fin (𓂄) doing?

In: Engineering

Answer 1

Many newer cars have the antenna cleverly incorporated into the wiring of the rear window demister.

The shark fin is a GPS antenna.

I find cars with extra antennas, particularly aftermarket ones centrally mounted on the roof, are often plainclothes cops.