On 14 Oct, 19:41, Roy Lewallen wrote:
Jimmie D wrote:

Normally WWV rxceivers have there antennas tilted at 45 degrees in an
attempt at polarity diversity. Im not sure if the department store clocks do
anything like this. The only one I have ever seen used a loopstic antenna.
The professional grade rx I am familar with that was used to set the time on
a computer used a contuously loaded dipole on an outside mount with 45
degree polarization.

*Chuckle*

Tilting would work fine if an incoming wave couldn't have any
polarization except vertical or horizontal. But it can -- it can be at
any angle. So it doesn't matter how you tilt the antenna, the
probability of the incoming wave's polarization being aligned with it,
at right angles to it, or having any other relationship to it, is the
same as for any other tilt. (For simplicity, I'm ignoring the fact that
the probability of a wave arriving with a particular polarization angle
varies with the elevation angle when ground reflection is involved --
which it virtually always is with HF skip propagation.)

A 45 degree tilt might be useful if you were receiving a line-of-sight
signal which might come from either a horizontally or vertically
polarized antenna. But even then, if the transmitter's antenna was
tilted 45 degrees the other way, you'd be cross polarized and in the
same boat as if one were horizontal and the other vertical.

One solution is a circularly polarized antenna, which responds equally
well to linearly polarized waves at any polarization angle.

snip
Doesn't a circular polarized antenna lose 3 db when responding to
linearly polarised waves?
IF that is the case it doesn't "respond equally as well"
As far as 45 degrees goes that is not correct for maximum response,
more likely a 45 +- 11 degrees would supply the most gain.
Kraus refers to this empirical tilt action in his chaptor on helix
antennas
which I now see as the summation of all radiator vectors when
expanding Gauss.
Art