Richard Fry wrote:
On Jan 14, 12:07 am, Art Unwin wrote:

It has not yet been proven that current does not flow thru
the center of a radiator.

Assuming that significant r-f current exists at the center of a
radiating conductor, where does it go when it reaches the end of that
conductor?


Ahh.. the famous "boundary condition"..

Say you've got a big bar 100 feet long and a foot in diameter, and
you've induced a rf current along it by some means. All those equations
with the Bessel functions tell you the magnitude and phase of the
current in some infinitely thin slice in the middle.

But, at the end, those equations don't hold. Essentially, the "reverse
current" flows radially across the end and forms part of the "forward
current" on the surface.

I doubt there is a good analytical solution of this. There's probably
some decent approximations (within 5% or something), but anyone who
really cares is going to do a FEM analysis of some sort and solve the
problem numerically.


RF