Initial research complete
This project stems from my earlier work with helical antennas. The idea is that if you take the general principal of a helical antenna, but make it taper at one end to a point, so that a cross-section looks like a cone. This might also be implemented as a spiral on a pcb, but I don't yet know what properties of the antenna this would change. My initial prediction is that the antenna would be highly directional, but be able to pick up a multitude of frequencies at a somewhat modest gain versus a single frequency at massive gain.
Catonic confirmed my assumptions on the directivity and bandwidth of the 3d version of the antenna. The wideband tendencies of the 2d spiral would remain the same, but the antenna might become less directional.
[[]] Kraus' antenna book at Amazon, Third edition. I (Catonic) have been told that the first edition has some math/explainations that were left out of the second edition.