Topband: Take off angles

[Dan Robbins]

When I worked at the old HF radar (ROTHR) site in Alaska there were
times when there were two different propagation paths evident.  One was
a high-angle path (Pederson Ray) and the other was a low-angle, normal
path.  I never saw the high-angle path as strong as the low angle one.
However, it dawned on me this may have been because our facility had
superb low angle capability.  Both TX and RX vertical arrays had a 1000
ft ground screen (a screen, not radials!) in front of them and then they
looked out over the Pacific Ocean, too.  It was not too hard to
visualize that an antenna with a poor ground under the same multipath
conditions might not capture that low angle path - in that case the
high-angle signal would predominate and a horizontal antenna might be
the best.  W8JI's "worst single investment" in a dipole at 5/8
wavelength might say something about that good Georgia soil in the far
field past the radials.

                                                    Dan KL7Y


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