Dear Group:
Long, long experience with angles above the horizon that are used by DX
signals (at HF) indicates that the most useful angles are between 2 and 12
degrees. Comparing the expected gain of antennas at 6 degrees provides a
good figure-of-merit.

That said, if one has a low, horizontally polarized antenna with very
little gain at 6 degrees, you might still work DX using more than an optimum
number of hops (angle of more than ten degrees). However, you will work DX
fewer days per month than someone who gets significant gain at angles
smaller than ten degrees.

I emphasize what Roy has said: the so-called take-off-angle (equal to
the smallest angle at which peak gain occurs) of an antenna is not
necessarily an indicator of DX performance.

Another example is the case of a horizontally polarized antenna that is
over 3 WL high: it has a small TOA but is likely to have a null at an
important angle smaller than 12 degrees. In other words: the
too-high-antenna works very well some of the time, but a lower antenna works
better at other times.

A useful goal for the (single) optimum (for DX) antenna is an antenna that
has its second null (first null is at zero degrees) at an angle greater than
12 degrees and a first maximum (what is called by many the TOA) between 2
and 12 degrees.

The actual angle used at the transmitter end of a DX circuit is
sometimes quite different from that used at the receiver end.

73 Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Bill Turner" wrote in message
...
Roy Lewallen wrote:


An antenna doesn't have a single "radiation angle". It radiates at
all angles. The relevant question is how much does it radiate at the
particular angle of interest, not at which angle does it radiate the
most.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

That's true, except few if any hams have a specific "angle of
interest", since different angles are used at different times. For
most of us, the angle of maximum radiation gives a general indication
of how the antenna will perform. A better indication would be a
graphical representation. It's always a problem when one tries to
reduce a complex situation like this down to a single number.

73, Bill W6WRT