Wimpie wrote:
On 7 ene, 04:25, (Richard Harrison) wrote:

art wrote:

"You did not 'determine" radiated power.....period"

Exactly right. Power in the near field is largely reactive. To determine
radiated power you measure the in-phase volt-amperes with a wattmeter.
The multimeter on the hood maximizes output same as a Bird wattmeter for
practical results, but you hanen`t quantified watts out.

Best regards, Richard Harrison, KB5WZI


Hi Richard,

You can determine radiated power and radiation pattern by near field
measurements (theoretically). Please search for "poynting theorem"
and "Huygens principle", "Huygens Source" or "Fresnel diffraction
theory". Most texts require differential vector calculus.


This is what is done on a near-field antenna range. For certain
scanning geometries, the math is fairly straightforward (e.g. Fourier
transforms). For others, it gets complex, especially if the scanning
points are not evenly spaced.


A further complication is that you need to make 3 axis measurements of
both E and H.

Jim, W6RMK