The first radios were spark gap transmitters (see Hertz's famous experiment). Though to be clear, Hertz's experiment was rather unconventional as the spark gap served as both the transmitting antenna (albeit a fairly noisy one) and also as a switch. Subsequent designs utilize the spark gap
only as a high voltage switch. In modern tank circuits, this "switch" is replaced with a solid state transistor (or similar type of devices).
Modern plasma antennas are much more advanced than the traditional spark gaps.
https://en.m.wikipedia.org/wiki/Plasma_antenna