Re: How many joules --> e.m. waves?

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

On April 19, 1997 Bob Sciamanda wrote:

> Corson & Lorrain is a second reference which agrees with [the radiation
> resistance formula for a magnetic dipol] R = 19200*(d/lambda)^4. This 
> reference explicitly states the restriction d<<lambda. This restriction 
> is inherent in any derivation which assumes the same instantaneous value 
> of the current at every point in the circuit (the loop).

This means that my calculations of efficiencies were wrong; I used the
R_rad formula outside the region of its validity. Yes, there is a price to 
pay by grabing a formula without thinking about its derivation. I will 
modify the capacity again (to be in the region for which we do have a
formula for R_rad) and will recalculate efficiencies, for those who might 
still be interested. And I will use the 19200 coefficient this time.

I just realized that there are two kinds of resonance in this problem, 
one for the oscillations of charge between C and L and one for the antenna 
itself. The first kind depends only on L*C; it determines lambda=c/f, where 
c is the speed of light. The second (standing waves) depends on (d/lambda). 

Mark wrote that high efficiencies are natural for standing waves. What
evidence to we have for this? Does anybody know how to calculate R_rad 
when (d/lambda) is not very small in comparison with unity? 
                                                              Ludwik