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June 24th 04, 01:57 AM

I think I just answered my own question...

(Dario Lopez) wrote in message om...
Sorry Roy but I disagree. Well,... I agree with everything you said
except for the "No" part and the conversion equations. You left out
one part too. The RCP and LCP components of an elliptical wave are
not equal otherwise they would collapse to a purely linear wave.

Here's an example I came up with.
Let E_elliptical = x + 2*j*y (left hand elliptical)
E_elliptical = RCP + LCP
= (a*x - j*a*y) + (b*x + j*b*y) = x + 2*j*y
equating coefficients...
a*x + b*x = x
-j*a*y + j*b*y = 2*j*y == -a*(j*y) + b*(j*y) = 2*(j*y)
or
a + b = 1
-a + b = 2
solving for a & b
a = -0.5
b = 1.5
so
RCP = -0.5*x + j*0.5*y
LCP = 1.5*x + j*1.5*y

which clearly isn't
Right Circ E = 0.5 * (Eh - j Ev)
Left Circ E = 0.5 * (Eh + j Ev)

Regards

Dario

Roy Lewallen wrote in message ...
No.

All waves are elliptically polarized. Linear and circular are two
special cases of eliptically polarized waves. For analytical and
computational convenience, you can split any (elliptically polarized,
TEM) waves into two orthogonal components. One choice of two components
is vertical and horizontal linear. Another, equally valid, choice is
left and right circular. You can convert between one and the other with
the equations I provided.

To be purely linearly polarized, Eh and Ev have to be in phase or 180
degrees out of phase. To be purely circular, Eh and Ev have to be equal
in magnitude, AND in phase quadrature. There is no combination of Eh and
Ev except both zero which result in the left or right circular
components to be zero. That is, a purely linearly polarized wave can
still be split into left and right circular components, and neither of
those components will be zero unless the field itself is zero. Likewise,
a purely circularly polarized field can be split into non-zero vertical
and horizontal linear components.

Roy Lewallen, W7EL

Dario Lopez wrote:
Thanks Roy,
But for those equations to be valid circular represenations,
don't Eh & Ev need to be equal? As they stand, substituting "random"
values for Eh & Ev will yield elliptically polarized waves.

Dario

Roy Lewallen wrote in message ...

Left Circ E = 0.5 * (Eh + j Ev)
Right Circ E = 0.5 * (Eh - j Ev)

where Eh and Ev are complex horizontal (phi) and vertical (theta)
linearly polarized E field components respectively. Left Circ E and
Right Circ E are of course also complex.

You can find this in just about any antenna text. A text would probably
be a good investment if you're going to be digging into theory at this
level.

Roy Lewallen, W7EL