Topband: Reducing QRN

[Tom Rauch]

> What receiving antenna could be used to reduce the QRN,
meaning some type of an antenna that could be rotated. Am
thinking of a K9AY on a pole or an antenna pennant or flag
antenna that can be rotated. I would think the front to back
ratio would reduce a lot of QRN. Please your comments.


Bill,

If the lightning noise comes from moderate to long distances
and is not in the direction of the DX station, then a
directional antenna will reduce the noise if it has a wide
enough null to reject the entire area where lightning noise
originates.

You can hear what my big phased Beverage arrays or vertical
arrays do at:

http://www.w8ji.com/dx_sound_files.htm

Pennants, Flags, and K9AY's really just function as a
two-element vertical array. The horizontal component of the
wires making up the antenna somewhat cancels because of
close spacing to earth and the other opposing wire, while
the vertical component is re-enforced by earth and not
cancelled as much because the vertical areas are further
apart and have phase shift that is not exactly 180 degrees.
Because this type of antenna derives phase delay from the
horizontal wires (they act as delay and transmission lines)
they are less than perfect in phase angle between the
vertical sections. The horizontal component is not perfectly
canceled, so they have a very high angle response that is
much more pronounced than a two-element vertical with the
same less than optimum current distribution and phasing.

You might just try a bunch of antennas during any given set
of QRN conditions, but largely you will find a sharp clean
pattern with a very wide null area and narrow main lobe will
be best. That means a BIG array. Otherwise you have to hope
the antenna you pick has a null in the direction and angle
of the QRN. My own experience is that Flags, Pennants, and
k9AY's are better than nothing (a small magnetic loop is
closest to nothing), but not nearly as good as other arrays.

You can find a list of directivity at:

http://www.w8ji.com/receiving.htm

Over the past 5 years my experience has been the pecking
order pretty much agrees with the order in that list.

My problem with the FT5 has been the storms and his signal
are from basically the same directions, and the storms are
within a few hundred miles. That makes it pretty tough to do
anything to hear him "solid" enough for a QSO. Either the
storms have to move direction, or he does.

73 Tom