I’m curious about the theory for how this design works. The wire at the base extend up to the top end of a cylinder, that is closed at the top and open at the bottom. Above that, is a small straight length, followed by a coil, followed by a longer straight piece. So what do the coil and the cylinder do? I suspect the main function of the coil is to increase the electrical distance without increasing physical distance to the top section, but what about the cylinder?
