Many slightly older cars (2000-2020) had antennas embedded in glass. The idea is solid. Antennas in glass are protected, so they can be very thin and almost invisible, more aesthetically pleasing than a shark fin or a rod on the roof.
I would consider this an aesthetic choice, not so much engineering. A small antenna sticking out on the roof solves the engineering problem adequately.
Though you are probably right and many cars with just FM/AM and DAB still put them in windshields.
I’m not sure about that 3+ antenna claim for FM. Do a fact-check there. ;) I think most diversity antenna systems that you describe use 2. And they are still considered “premium”. 3 is a bit overkill for FM, FM is very resilient against obstacles.
If I’m wrong, would be interesting to see an example of a car that uses 3 or more. Probably far outside of my pay grade to say the least.
They really didn't want you losing signal!
This isn't even mentioning the festoon of other antennas for DAB, mobile (which has a backup too and phones home in a crash: in case the shark fin is broken in a crash)
It’s cool they did that but it’s almost like they are trying to prove some point — maybe to be the best in the market for FM by a hair. :) One antenna is more common than 3 to my knowledge, by far.
It had a magic box that used feedback from the stock radio's IF section to (try to) erect the best pattern for good reception at any given time, and which presented one unified RF output to that radio's singular input.
Cadillac has used the same, or very similar, system as well.
Which is neat and all, I guess, but we seem to be getting off into the weeds: These antenna elements were not invisible at all except for the fact that they blended in with the heated defroster elements that were also printed onto the glass.
This is probably so the car can act as a Wifi hotspot, with the Wifi antennas located in the interior rather than in the sharkfin.
It also can act as a hotspot if I bothered paying for its data plan. I'd rather if I could just load an eSIM for my existing service to have it be a hotspot for me. Since its antennas are on the outside it should get way better GPS and cellular connectivity than my phone in my pocket deep in a metal box.
I've seen what you are talking about, too. My VW RNS had settings to use the car's 4G for passenger WiFi.
Cars really want to phone home these days