Expedition antenna for the bands should have length
not less the 9 meter and no more the 21 meter. Why? Because we
need antenna that would be work without counterpoises, so, the
antenna should have length lambda or lambda/2. Shorten antenna
has low efficiency, long- high weight.
Wire in length 10-meters
would be enough if you would like to use bands 14- 28- MHz at
the expedition. Antenna with such length is suitable for local
and DX- QSO on 14- MHz and has good efficiency on 18- 28- MHz.
Such antenna still is working on 7-MHz (lambda/4 length).
Wire in length 20-meters
would work efficiency on 7- and 14- MHz as well as at 18- 28-
MHz. The antenna provides local QSO at the 3.6- MHz. However at
good propagation and if the end of the antenna is hanged up at
10 and more meters the antenna allows to make DX-QSO on the 3.6-
would it hang up?
Classical mountain expedition antenna is Sloper. Figure 1 shows the antenna. Use any natural support-
tree, stone, etc., to install the antenna.
For Sloper having length
20 meters use additional support. It may be any natural support-
tree for example, or artificial- plastic fishing pole, for example.
shows Sloper 20 meters length. DD of
the antennas shown on Figure
1 and Figure 2 has maxima radiation in direction of
the incline of the antenna wire.
Antenna wire may be placed along the fishing pole.
DD of the antenna has maxima radiation into another side from
the incline of the wire. Figure
3 shows Sloper with fishing
pole as antenna part.
It is possible to install support or fishing pole at
any place of the wire. In this case it is a variant of an asymmetrical
dipole with the end fed. Figure 4 shows the antenna. Good solution is to
install the support in the center of the antenna wire how it is
shown on Figure 5.
In this case we have got a kind of I.V. antenna with the end fed.
The antenna has enough efficiency at 7- and 14- MHz.
The feature of the Sloper
antennas on the base of one wire is that all of the antennas are
radiated almost 50/50% horizon/vertical polarization. It looks
like a lack of the antennas. If you need antenna with the vertical
polarization you may try helical antenna shown in the Figure 6. However the antenna needs good grounding