Understood. I will likely be building mine of 14 AWG stranded PTFE-insulated wire, encased in PVC pipe, except for the coil which will be eternal to the pipe. (I have most materials already on-hand.) I will use the .81 velocity factor of PVC for calculating element and stub lengths. Thanks again, and I'll post results when I get it on the air.

Thanks for sharing this work. I am on board with your phasing coil approach. I have two questions about the antenna not related to the coil design. 1) Assuming that you're using a standard 1/4 wave J-pole matching stub, what is the spacing between the element and the stub? and 2) Did you compensate for the velocity factor of the PVC pipe radome/jacket in calculating element lengths?