What are these loops above the tracks at each AirTrain station for?
The shape and position certainly suggests a magnetic antenna, or really just one half of a low-power transformer, with the matching counterpart on the top of the train.
Inferring from the use case: might be a simple way of exchanging data with the train; it's probably going to be rather low-bandwidth (seeing that the carrier frequency couldn't be high and loops are inherently relatively narrow), so low-rate, but probably enough to exchange a short audio sample and maybe time information in the station, or to transmit &quot;train speaker grade&quot; live audio.
It all reminds me of the inductive wireless audio systems for hearing aids.