Art Unwin wrote:
"Remember, Richard was replying to the initial post which was very
specific in nature regarding lab testing and degree of error."

Antenna test facilities involve far fields. Kraus says on page 831 of
his 3rd edition of "Antennas":
"---it is obvious that measurement usually takes place in the far
field."

This can be far indeed with highly directive antennas.

My initial response included:
"A lab may put its stamp of approval on your instrument, but your best
assurance may be measurement of known values. The termperature of
ice-water or the voltage of new dry cells, for example. You usually can
try several dry cells for confirmation or averaging.

In antennas, one strategy for successful gain determination is
comparison with an antenna of known gain."

My posting was imperfect. There`s nothing that can`t be improved, but
were I re-writing my posting, I can`t think how I might improve it.

I don`t think my example of checking gain of an array using skywaves was
amiss. We build shortwave antennas to use skywaves. We give antenna
gains in free-space because it makes sense.

I said we built a small-scale model first because we can measure the
model`s characteristics without a helicopter. The full-scale antenna
performed exactly like the model. Computer modeling has eliminated the
small-scale model step in new designs.

We checked only the first off of the new design, with the full
confidence that subsequent antennas of the same design would perform the
same.

Of the first antenna, we measured everything including the currents
along each element. We used an R-F ammeter in a loop suspended from the
element and towed along with a string. We read it using a telescope. The
antenna was a scientific success as well as a practical success. This
differs from some of the oil wells I was to drill later, though some of
those succeeded too.

I can only post what I know and it will never satisfy what everybody
wants to read. Sometimes my postings are more responsive than others.
That`s part of the fun.

Best regards, Richard Harrison, KB5WZI