Why antennas on truck fenders but installed in windshields cars?

[sklunk]

I think the big 3 all have them on the roofs of trucks. That seems to also be the new standard for cars too.

The small "sharkfin" antennas on the roof are for satellite radio. All the new Chevy, Ford, and Dodge trucks also have a traditional steel antenna on the fender to receive AM/FM.

 

[PILOON]

An efficient antenna needs to be at a % of frequency wave length.* 1/2. 1/4, or 100% of wave length as per known formulae.
Very specific formulae exist for maximum efficiency.
Otherwise it is a comprise.
Also important is the 'ground plane', again a ratio of the frequency
That being said everything else is cosmetics with compromises.
Then you have UHF, VHF and then the AM stations that are low frequency as compared to FM channels
LOL add satellite radio and you further confuse the problem.
Automotive engineers are for sure more concerned with the 'looks' than radio reception hence the new little 'stubby' antennae sported on most cars.
Trucks however still sport the long 'whips'.

 

[bumperm]

A vertical "whip" antenna, by its nature is vertically polarized and omnidirectional (theoretically able to receive radio signals equally well from all directions), the vertical polarization matches the radio station for optimum results. . An antenna in a windshield will typically sacrifice performance due to it's location. It will not receive signals equally from all directions, and it's polarization may be a compromise as well. This may not matter much when the radio station is near, but reception of more distant stations can be worse than sub-optimal.