Sorry guys, I mixed 2 problems related to noise.
There are first the noise generated by beam vs quad, but I cannot estimate
the noise level, excepting that the quad is more silent under high wind.

The 5-10 dB less for the quad are related to the white noise. I explain.
According a swedish OM, it appears also some kind of white electrical noise
on a beam compared to a quad. The theory/argument is that the Yagi is more
prone to picking it up due to its high impedance at the dipole ends.

Quoted and translated from Swedish:
"The noise I talk about is on eg. 20 m and 5-10dB above the threshold on a
yagi but barely audible on a quad. It has always the same strength
independent of the time of day, possibly a bit weaker at sunrise. The noise
from static discharges are completely different. The noise I am talking
about is more "white"."
Quoting the list: "I have performed tests between Yagi/quad specailly on 20
meters. I have used a 5 el monoband yagi and a 6 el monoband quad. The
difference is about 5-10dB. The direction seems to be irrelevant, the white
noise is everywhere. "

The origin of noise is unclear but thoughts are (and these are
speculations): Perhaps the first skip of NVIS-noise from a town nearby? Or
that the quad's liftoff angle is different that the yagi's and so picks up
anything from another angle?

Can someone confirm this better performing of the quad ?

Thanks
Thierry
ON4SKY

"Thierry" To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote in message
...
Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
...