What ever program you use let me know the result for a fat dipole.
Walk the walk ! Forget the talk!

Are you sure you have not violated the segment length/wire diameter
ratio? From Cebik; Intermediate Antenna Modeling: "In NEC-2 it
is especially important to keep the segment length (greater than)
about 4 times the wire diameter. You may reduce this value by half
by invoking the EK command." Also, what does your "Average Gain
Test" report show?

73,

Frank