On 14 Feb, 18:46, "David G. Nagel" wrote:
art wrote:
On 14 Feb, 09:55, "David G. Nagel" wrote:
art wrote:
On 13 Feb, 22:18, "Jerry Martes" wrote:
"Bobby" wrote in message
egroups.com...
All,
How do you determine the axial ratio from a RHCP wave to a LHCP wave
from an antenna? In essence, I need an axial ratio transformation from
RHCP to LHCP.
Any ideas on the equation or where I can find it will be helpful.
Thanks.
Bobby.
Hi Bobby
If you are working with an antenna that radiates RHCP it is totally
insensitive to LHCP.
If you have an antenna that radiates "RHCP" (or LHCP) the axial ratio is
the ratio of the Minor axis to the Major axis of the E field. So, it
varies from zero to one as the radiated field varies from Linear to
Circular.
Jerry
You mentioned insensetivity above, are there any other polarities
insensitive to others ? I note that weather antennas are now migrating
to
dual diversity antennas for horizontal and vertical, is it possible to
totally isolate those too.?
Art
Any cross polarization situation will exhibit insensitivity to others.
For instance take a vertical antenna and a horizontal antenna at a
distance. There is a signifant reduction in signal strength.
Or take a dipole oriented NS and a dipole oriented EW and you will see a
loss of signal also.

Dave WD9BDZ- Hide quoted text -

- Show quoted text -

David, could you add to your posting some of it doesn't seem to jive.
Art

Art;

OnPage 23.35 of the ARRL 2006 Handbook is a Graph showing the relative
loss between two antenna's for various angles from 0 degree to 90 degree
misalignment. For 0 degree misalignment there is no loss, at 50 degrees
there is a 3.84 dB loss and at 80 degrees there is a loss of 15.2 dB. 90
degree misalignment shows an infinate loss. This is for linear
antenna's. Circular Polarized antennas of opposite turns show an
infinate loss between two antenna's.
If I can help further please feel free to contact me direct:


Dave WD9BDZ- Hide quoted text -

- Show quoted text -

David I am not privy to a copy of what you are talking about but we
may be talking at cross purposes. My point is that a element at right
angles or parallel to the earths surface cannot present a pure
polarised field.
When looking at a radiating beam you have two vectors, one at right
angles to the other, therefore I fail to see how radiation would
appear at right angles to the earths surface. True the right angled
vector is reduced when it is broken up into two vectors when it is
seen as curl but the horizontal vector cannot be removed or cancelled
unless the element is tilted somewhat.
Anybody can prove this to themselves by the use of the plethora of
computor programs Admittedly the tilt required is small but it is
there none the less.
Art