NEC-LIST: Efficiency of Short Dipoles

Good day folks.

Time for me to add my two cents as well.

Recently I had occasion to look at some short and wideband dipoles.
The wideband dipoles were wideband by virtue of extremely lossy
matching networks. In addition the wires were thin stainless steel
rope. The short monopoles/dipoles were also stainless steel. Now in
the loss calculations the conductivity of the stainless steel may not
reduce the efficiency of the antennas beyond acceptable levels.
However, the parentage of the material was dubious and I have been
unable to find out what the relative magnetic permeability, Mu(r),
was. From a previous round of responses from the NEC-LIST group it
appeared that the Mu(r) could be anything between 1 and 1000 depending
on grade. If anyone is interested in this material let me know. I
will happily forward the file, or post it on NEC-LIST depending on the
level of interest.

So on all this, I would like to add a word of caution. Not all
versions of NEC in use have been modified to account for the Mu(r).
The ohmic losses will increase as the square root of Mu(r).

Hope this helps someone out there avoid embarassment when he/she has to
do calculations using some weird and wonderful material, such as
galvanized steel, or stainless steel for whatever reason.

Have a great day just the same, Duncan Baker.

See Note re home phone number below.

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PROF. DUNCAN C. BAKER, DEPT. OF ELECTRICAL AND ELECTRONIC ENGINEERING,
UNIVERSITY OF PRETORIA, PRETORIA, 0002, SOUTH AFRICA.

EDITOR-IN-CHIEF, ACES JOURNAL.

PHONE +27 12 420 2775 (OFFICE), +27 12 47 7480 (HOME)
        NOTE - the home number will change some time in 1998 to:
                +27 12 361 7480
FAX +27 12 362 5000 (OFFICE), +27 12 348 5314 (HOME)
E-MAIL: DUNCAN.BAKER_at_EE.UP.AC.ZA (PREFERRED ADDRESS)
        IEEE alias address: d.baker_at_ieee.org OR duncan.baker_at_ieee.org
        Private server address: apc_at_acenet.co.za
LOCAL STANDARD TIME = UT+2 HOURS
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Received on Fri Nov 28 1997 - 09:57:14 EST