I wrote:
"However, there is a measured by D.C. Glockner of Ohio State University
pattern of the 3-element Yagi-Uda with more than 7 dB gain and almost
zero radiation from the direction of 180-degrees from the maximum. It is
on page 246."

No correction required but I should add that the book is the 3rd edition
(2002) of "Antennas" by John D. Kraus et al.

Best regards, Richard Harrison, KB5WZI