FreeLists / si-list / [SI-LIST] Method of images for approx analysis of conductors near ground ?

[Steve Rogers <SRogers@xxxxxxxxxxxxx>]

The effects of locating a current carrying conductor near to ground can be
(I think) determined by the method of images. As far as my knowledge goes on
this the location of a conductor x near to ground causes an equal but
opposite (direction of current flow) current to flow in the ground. This
image current is in essence giving the same effect as having two conductors
identical to conductor x spaced at a distance of twice that of con x to the
ground surface. I think this is about right?

Now, the above reasoning is only true for a perfect conductor (I think). My
question is then...
can we apply the theory to a current carrying conductor x over a lossy
ground ? If so how do we do this?? Part of me says its probably a trivial
modification, but I have a nagging doubt that there maybe somthing that I am
missing here. 

The reason I ask about the above is for an approximate analysis of inductors
over real ground planes (copper clad board, aluminium casing etc). Many of
these structures are comprised of straight elements (planar square spirals
for instance), The mutual inductance equations for straight elements have
been done to death (Grover). So, if the image theory can be adapted to
account for real conductors, the effect of bringing these structures near to
real grounds can be analysed. The nice thing is you dont need an E-M solver.
It is worth noting that where the conductor geometry gets nasty (solendoids
etc), the mutual inductance for many of these cases is also available (most
of it in Grover).

Anyway, THE QUESTION IS.... IS THE IMAGE THEORY ADAPTABLE FOR LOSSY GROUNDS
AND IF SO THEN HOW, any comments on this subject are welcome....

Thanks in advance

SGR

Steve Rogers B.Eng (Hons) AMIEE
RF Design Engineer
Micromill Electronics Limited

Tel: +44 (0) 23 9236 6600
Fax: +44 (0) 23 9236 6673
SRogers@xxxxxxxxxxxxx

Micromill Electronics Limited, Leydene House, Waterberry Drive,
Waterlooville, Hants, PO7 7XX, United Kingdom
Registration No. 1456922 (England). Registered office as above.


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