Police possibly using a radio communication intercepting vehicle at a protest: what could they do?

Police vehicles always have bigger antennas since they communicate with one another via radio but yesterday I've seen a vehicle with no labels with bigger and wider antennas not too far away from a protest and it reminded me of a video where someone said they use this tactic, but what for? Intercepting calls? But I doubt that someone has shady conversations over plain phone data. The protest was allowed and regulated by the local police office.

communication far police privacy protest radio vehicle vehicles video