Satellites
Satellites are an absolutely facinating part of amateur radio - to which you can learn a vast amount on modulation modes, antennas, tracking to name a few…
Many Amateur Radio satellites exist which, provided you own a licence, are able to uplink data - usually to contact other people - the most notible being the International Space Station which hosts a FM and Packet radio repeater
On this website I am assembling a list of different satellites to document how they operate along with how to downlink or uplink data