Richard Harrison wrote:
Cecil Moore wrote:
"What am I missing?"

Radio waves spread during propagation. Huygens` principle is a cause.

But the Method Of Moments used by NEC for antenna
radiation patterns calculates the interference at
a point in space based on radiation from different
elementary dipole sections of the antenna. For
instance, when the antenna is two wavelengths long
there is no more broadside radiation than there is
radiation off the ends.

In "Antenna Theory" by Balanis, in Chapter 8, page
407, on Moment Method, he illustrates the method
using radiation angles less than 45 degrees to
the radiating element.
--
73, Cecil http://www.w5dxp.com