Wes,


Of course I didn't assume that there is one "take off angle", but I did
realize that there is a theoretical optimum take-off angle, and that
the field strength diminishes as one moves away from that angle in a
generally smooth and continuous way. This is obvious on any antenna
radiation pattern chart. The point I was getting at was that the field
strength diminishes in both the horizontal AND vertical planes. The
common antenna rotator allows directing the radiated field in the
horizontal plane, thereby "peaking" the signal in that plane.
There seems to be very little attention paid to peaking the signal in
the vertical plane, which can be readily accomplished by raising and
lowering the antenna height. I was curious as to the discrepency. The
mechanical complexities just don't seem to fully account for the
disparity in usage of these thechniques. I would estimate that
rotators are at least 2 orders of magnitude more common than variable
antenna height mechanisms. Since I'm assuming that both vertical and
horizontal components of feild strength are important in HF signal
propogation, I was wondering why so relatively little attention is paid
to peaking the vertical component. Is it because of mechanical
complexity, lack of understanding, or something else?

73,
CW-AI4MI




Wes Stewart wrote:
On 14 Oct 2006 06:32:21 -0700, "CW" wrote:

Fellows,

I've been wondering for some time now why amateur operators don't build
their Yagi antenna's
so they can be raised and lowered about 10ft in addition to being
rotated.
[snip]

You make the all-too-common assumption that there is one "take off
angle" and apparently believe that no usable radiation occurs at any
other angle.

You wouldn't (I hope) believe that there is one azimuth angle and that
if your antenna isn't pointed *exactly* at the target you're SOL, so
why the concern about height?