You're confusing 45 degree linear polarization with circular
polarization. Even though both have equal horizontal and vertical
components, they're not the same. The difference is that in a linearly
polarized wave, Eh and Ev are in phase. In a circularly polarized wave,
they're in phase quadrature (90 degrees out of phase with each other).
That makes a large difference.

QSL, I plead guilty to confusion and oversimplification, I really meant
"slanted linear" polarization.

No, you're right. It's dual polarization. And you're also wrong, since
it's also single polarization (left-slant or right-slant linear).

Well (as belowed Ronnie would say), I feel more right in the quest for design
of antennas that minimize the polarization fading and cover wider vertical
angle range. I have used slanted polarization quads with good results and I am
willing to pay small 3 dB pealty for the better coverage and fewer nulls in the
pattern (in order of 10 - 20 dB). Plays well in the ocean front locations.
After waves go through the ionosphere, who knows what polarization they are.

People with a deep interest in this topic might benefit from the new
EZNEC+ program type, which can display the field strength from any
antenna in terms of left and right circular as well as vertical and
horizontal linear components.

Roy Lewallen, W7EL

Thanks for the new + one, I have not explored it yet, but looking forward to
use it and play with 2m (hard) models to verify few things, including insulated
wires in the Quad elements.

Yuri, K3BU.us