It really is from "Funkentechnik": "Spark technology". I wonder how many people appreciate the post for the cute etymology and how many because it sounds funny.

Good information for ham radio people, too. Hobby sounds too geeky? Just say you're into Über-Funk-Parties.

Pretty much the first type of commercially viable radio transmitter was the spark-gap transmitter ("Knallfunkensender" in German). It worked by charging up some capacitors to up to 100kV and then letting them spark. This spark sent a massive banging noise on the whole radio spectrum, which could then be turned into an audible noise using a very simple receiver. That was then used to send morse codes (or similar encodings).

They went into service around 1900, and by 1920 it was illegal to use these because they would disrupt any and all other radio transmissions in the area with a massive loud bang.

There were electrochemical cells (invented in 1800) that provided a constant current for some time.

Idk the details. Look up Galvanic cell, Volta cell.