Re: NEC-LIST: thin-wire general EM equations

This was done thoroughly in a paper by T.T.Wu (of Harvard) in the
mid-60s (I think - could be 70s). Can't find the reference ATM.

I used it in a paper, calculating the impedance, max directivity etc of
dipoles up to about 20 wavelengths long IIRC:

P.S. Excell and D.P. Howson, 'Assessment of Worst-case Receiving Antenna
Characteristics of Metallic Industrial Structures. Part 2:
Electrically-large Structures', Jnl. IERE, Vol. 56, No. 1, 1986, pp.
33-36.

Trouble is, none of this stuff is online and my hardcopies are buried
somewhere.

Peter Excell
Professor of Communications
School of Computing and Communications Technology
Glyndwr University Wrexham
Wrexham, Wales.
www.glyndwr.ac.uk/computing/research/PE.htm

-----Original Message-----
From: nec-list-bounces+p.excell=newi.ac.uk_at_robomod.net
[mailto:nec-list-bounces+p.excell=newi.ac.uk_at_robomod.net] On Behalf Of
GrantBingeman_at_cs.com
Sent: 08 June 2009 21:22
To: nec-list_at_robomod.net
Subject: NEC-LIST: thin-wire general EM equations

Gentlemen: it seems that all textbook introductory treatments of
freespace
dipole impedance and EM fields limit themselves to dipole lengths less
than
about a half wavelength. This is related to the simplifying assumptions

made when defining the Hertzian dipole. I am looking for a general set
of
equations, assuming sinusoidal current distribution on thin wires, for
the
input impedance seen by a source located at the center of the dipole. I
am not
interested in any MoM approaches, just the plain old CI and SI
expressions,
requisite integrations, etc. Surely there must be a general equation
for
this that is valid for any length of dipole?

PS: when i say thin wires, i do not necessarily mean infinitesimally
thin
wires. g

Grant W. Bingeman, P.E.

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