gareth wrote:
On antennae that are several half-wavelengths long (beverage, Rhombic, etc)
what does the radiative wavefront look like when close to the antennae, even
though it is presented in the literature as a plane wave further out?

Run just about any version of NEC and look at the near field data
and find out.

The reason that I ask is the on such longwires, there are parts of the
wire which will be radiating positively, and parts negatively, thereby
suggesting that the outgoing wave, spherical though it might be, has
a +/- modualtion were you to travrse its circumference?

Are you attempting to say the pattern has lobes in as many words as
possible?

Shape of the wavefront tells you little about the workings of an
antenna as an antenna as it depends on things like the emitter area and
distance from the emitter.

Example:

Sunlight from the Sun has a spherical wavefront, but at the Earth's
distance of 150,000,000 kilometers you are hard pressed to measure the
difference from planar.


--
Jim Pennino