[souterrain]

There are a number of compact shortwave (radio amateurs prefer the term "high frequency" or HF, in contrast to VHF, UHF) transceivers. The impracticality is from the size of an efficient antenna.

I have personally made voice (single-sideband or SSB, which is analog like AM without wasting energy transmitting a carrier or redundant sideband) contacts with a 5 watt portable (Elecraft KX2) between countries in Europe, using a meter-long whip antenna and a trailing counterpoise wire.

These radios are incredibly complex weak-signal equipment, and that is reflected in the price.

That said, it is fun. Using morse code to do the same is even more fun.

I would never rely on this for off-the-grid communication, though.