It may be recalled I recently reported an error in program GRNDWAV3
which deals with groundwave propagation from a short vertical antenna
versus frequency and type of terrain.

Although the field strength at the receiving site was correctly
computed, the available receiver input power was exactly 6 dB greater
than it should be.

The error was due to a misunderstanding of vertical antenna gain
relative to an isotrope when mounted above a groundplane. It appears
some of the learned text books are unclear on this point.

My immediate problem was eventually sorted out by Roy and proved by
EZNEC-type programs which are not interested in man-made notions about
antenna gain and isotropes.

The faulty program has now been replaced by program GRNDWAV4 which
makes no use of antenna gains at either end of the path. Download it
and delete the older version.

I am grateful to Icelandic radio amateur, Villi, TF3DX for informing
me of the error. He went back to fundamental principles to prove me
wrong. I have no idea what aroused his suspicions and we are not in
contact with each other at present. He said he intended to write a
paper on the subject.
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Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
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