NEC-LIST: Back to equivalent areas for nEC

Hi folks.

This topic seems to have died down before I could make much of a
contribution.

Strikes me there are two reasons why one wants to look at the effects of
different geometric cross-sections in this case. The first is to be able
to predict impedances accurately using cylindrical equivalent cross-
sections eg. rectangular booms for VHF/UHF LPDA, the second is to predict
ohmic losses accurately, eg. VHF antenna on motorcar made of steel (don't
forget to include Mu(r) for steel) by approximating actual vehicle surface
area.

Some time back I obtained from my brother Dirk Baker a single page graph
taken from :

Meinke and Gunpach
Tascenbuch der hochfrequenztechnik
3. Auflage, Springer Verlag, 1968, Abb. 12.5, sorry no p. no.

This figure shows the characteristic impedance Z(l) for identical
rectangular conductors, with side ratios d/b varying from 0 to 1, and
spacing a such that b/a varies from 0.1 to 10.0. d/b less than or equal
to 1, ie. b is longer side, and a is spacing between them.

Also shown is Z(l) for a single rectangular conductor over a perfect ground
plane, again for the same ratios of d/b, and b/a, where a is spacing to
plane.

Hope this is of interest to someone out there. If anyone is interested
and cannot track down the reference, please let me know and i will gladly
send you a copy for personal use. Copyright prohibits my scanning it for
placement on the ACES Web page.

Have a really great day regardless, Duncan Baker.
*********************************************************************
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)
FAX +27 12 43 3254 (OFFICE), +27 12 348 5314 (HOME)
E-MAIL: DUNCAN.BAKER_at_EE.UP.AC.ZA (PREFERRED ADDRESS)
        d.baker_at_ieee.org (IEEE alias address)
LOCAL STANDARD TIME = UT+2 HOURS
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Received on Tue Apr 08 1997 - 09:57:09 EDT