antenna covers the 80, 40, 30,
20, 17, 15, 12, 10 and 6 Mx Amateur
bands. Multiband operation is achieved
by use of 300 ohm balanced line fed
to an antenna tuner. This
loop antenna needs to be run in the
horizontal plane. ie. parallel to the
ground. The formula used to determine
fundamental frequency wire length is :- Length
(feet) = 1005 / Frequency (Mhz). I operate mainly
CW, so I cut the wire length, for
the 80 Mx band, to 88 metres (287
feet). If you operate SSB, the length
of the wire will need to be shorter,
in accordance with the above formula. I used high
tensile fencing wire in the shape of a
square supported by four trees. The winds
here can be ferocious so strong wire
is needed even though radiation efficiency
will be compromised by using fencing wire.
Since our HF bands are harmonically related,
of wire covers all HF bands from 80 mx up to 10 mx, including the WARC
bands. If the
wire is cut for the 40 metre band,
about 44 metres of wire or slightly
the antenna can also be used on all
the higher HF bands. Of
course, a perfect square of wire is
far from achievable here. A circle is
theoretically ideal but even a triangle of
wire will work. The feedpoint
of the antenna can be placed any where but I positioned
it about two
feet from the corner. The diagram
below gives you some idea of the
shows one of the trees to which the
wire is attached.
The trees at this location are not
very high so the average height of the
antenna is only about 20 feet or so.
can be seen on the left. I used 15
metres of 300 ohm ladder line
position located in an old caravan which
is solar powered. The tuner can be
seen on the
left. The radio
is the Yaesu FT-450.
The Tuner -
Even at a low height,
performs very well. Surprisingly so. One of its attributes
is that it is quiet on receive.
Another is that it has many radiation lobes and
therefore works well in several directions.
It costs little to build. It's straight forward to construct and
fairly easy to erect, although in my
case I had a sore shoulder after
throwing the lines up into the trees. This multiband horizontal loop may be the antenna
you are looking for.