@neauoire omg I did see this thread when it started, I didn't think it would've grown this much.
@neauoire @Arteneko Regulations depend on what country you're in. There's a bunch of internationally-agreed-upon standardized frequency bands for amateur radio. Getting licensed differs for each country. This actually seems to give a nice summary of things https://en.wikipedia.org/wiki/Amateur_radio You can get into just listening in on stuff with a $20-40 USB radio receiver ("SDR" or software-defined radio). That includes picking up image transmissions from ISS, or weather satellites. There's so much stuff!
@Arteneko Our use of radios is very .. practical, not really theoretical. But I know there are a bunch of amateur radio fans on here in this thread who would be better to help you out.
https://merveilles.town/web/statuses/105749350480620955