it looks different than what I saw it to be 1-2 years ago. Maybe it was a different site, but this one is very similar, thanks

thank you all

Exactly, I’d still place bursts of radio signals (like that of a pulsar or morse code transmitter) under the umbrella term “radio communication”. Just because it uses the radiation that is at the radio frequency. No matter what the format/arrangement/method, which includes encoding and using carrier waves.

Then you also have electric waves that travel through conductors, although this is only a part the electromagnetic wave used in the air. But you can change the frequency of this electric wave perhaps to the radio frequency. So perhaps there is also radio communication through wires

How about not using such a small mail box