John Poet wrote:
I've gotten the idea that I could shorten the physical requirement, by
using RG-58 coaxial cable instead of regular wire, and taking the .66
velocity factor into account---

The velocity factor applies to differential transmission
line currents, not to antenna currents which are common-
mode. Instead, it sounds like you need a loading coil
opposite the feedpoint.
--
73, Cecil http://www.w5dxp.com