Art wrote:
"Now to avoid nitpicking are you saying that E=IZ cannot be used for
calculations at the end of an antenna and if so "WHY"?"

It is complicated by multiple currents. Like an open-circuited
transmission line, electrical conduction stops at the end of the
conductor. Current then becomes a phasor problem.

Collapse of conduction current induces a voltage which combined with the
incident voltage almost doubles the total voltage at this spot in many
cases. This reverses the direction of current in the conductor. Due to
capacitance at his high-voltage spot with the iniverse, displacement
current flows into free space from open-circuited antenna ends. It is
usually smaller than the conduction current.

Best regards, Richard Harrison, KB5WZI