NEC-LIST: Green's functions in NEC

Re David Jeffries Post.

Unfortunately, I do not have easy access to "R E Collin's book on Antennas
and Radiowave Propagation
", however, I do have the NEC2 documentation. The electric field equations
typically include a term G0, which is the Green,s function for the magnetic
vector potential A, and electric scalar potential V. These potentials do
indeed fall off as 1/r for a current element (A) or charge element (V),
even in the near field region. However, the equations for electric field
include a gradient of G0 (e.g. equations 73 and 74 of NEC TD 116, vol. 1)
as you would expect from E=j omega A - grad V.

Sometimes it can really appear that mutual impedance can fall off as 1/r,
depending on how the integral is formed. See for example
http://www.emproto.com/PhDThesis/zab.html on my site. The integrand does
fall of as 1/r, but the integral as a whole does not.

By the way, I have started a small NEC2 page
http://www.emproto.com/nec2/index.html.

Mark Tilston

-- 
The NEC-List mailing list <nec-list_at_gweep.ca>
http://www.gweep.ca/mailman/listinfo.cgi/nec-list