On Fri, 20 Jan 2006 04:16:39 GMT, Owen Duffy wrote:

In my limited experience, I have not seen commercial HF installations
with radial / ground wires laid above ground in preference to being
buried. The only cases I can recall were because of rock.

Whilst there are articles around about the performance of shallow
buried radials, I have not seen any that deal quantitatively with
radials laid on the ground, or pinned to the ground as you describe,
and the effects of those different installations on antenna
efficiency. That is what I was asking about.

Equally, there a plenty of articles where the author insists that
radials cannot work near the ground and they need to be some distance
above, some stating a quarter wave above.

Hi Owen,

These three paragraphs reveal arguments that vary by application,
rather than by degree. It seems to me that most AM stations' ground
fields are shallow buried in gravel simply to permit foot traffic. The
HAARP site uses a grid that is elevated sufficiently to allow
vehicular traffic. Neither really attend lightning as they are more
ground screens and principally constructed for RF.

I found a much more compelling report in:
UNITED STATES DEPARTMENT OF AGRICULTURE
Rural Electrification Administration
REA BULLETIN 1751F-802
SUBJECT: Electrical Protection Grounding Fundamentals
Which is vastly more comprehensive and directly answers these
questions when viewed in the terms of the resistivity of the earth
connection.

73's
Richard Clark, KB7QHC