Yuri, K3BU wrote:
"Properly designed and built Quad will beat Yagi in all the Above
mentioned "parameters"."

The author of "All About Cubical Quad Antennas", Bill Orr, W6SAI says:
"The power of the 3-element or 2-element Yagi, however, is not swept
aside by the Monster Quad, no matter what the size and power gain of
this impressive antenna."

Orr says measurements with an accuracy of a decibel or better are hard
to believe. His table shows about 1.7 dB advantage for a Quad with 2 or
3 elements over the Yagi, and the boom length may be about 2/3 that of
the Yagi, he says the reason for building a Quad instead of a Yagi is
likely a matter of opinion as to the value of the small edge the Quad
may have versus the extra cost and effort to get the Quad up.

Orr says he used both the Yagi and the Quad for years as did many of his
good friends. He says objective and subjective tests show the Quad has a
definite advantage in terms of signal strength over the Yagi antenna.

Best regards, Richard Harrison, KB5WZI