Art Unwin wrote:
"I do believe that this posting should put an end to this thread and I
thank you again for your input."

All the questions answered? Any topic is eventually tiresome, but not
everyone tires of it at the same time. Gain per unit length is likely
not a straight line at any particular frequency. There is probably much
more to be said about best coupling for maximum gain.

There was an article by Joe Reisert, W1JR in the December 1986 issue of
"Ham Radio" about a 28-element, 21-foot boom, 432 MHz (about 70 cm WL)
Yagi Joe built. The gain was about 19 dBi, or about 0.9 dB per foot at
432 MHz.

The pattern shown and gain are said to come from MININEC.

Best regards, Richard Harrison, KB5WZI