Maybe a60hz or light coil are impractical but what about a 100mhz
tesla coil. It would likely look like a 1/4 wave antenna or a helical
resonater. The primary might look like matching stub used to match the
coax to the antenna. I'd guess you'd run it with a big VHF tube as I
suspect a spark gap won't work at that frequency. This might give some
interesting effects.
Steve Z