b. Improvising a whip antenna. If the top portion of a whip antenna is
unusable, use a tree limb or pole to support an improvised wire antenna (Fig
34).
If the correct length cannot be determined by measuring, use the
wavelength formula.
REMEMBER:
Since whip antennas are quarter-wave antennas, the answer to
the formula L =
142
must be divided by 2.
F(MHz)
If other wire is not readily available, use WD-1/TT field wire (twisted
pair).
To make the twisted pair act as a single conductor, remove
approximately 1 1/2, inches of insulation from each end, and twist the bare
leads together (Fig 35). Now, splice the wire to the base antenna stub, and
tie (tape) the wire to the pole.
Lash the pole to the antenna base (Fig
34).
Figure 35.
Using WD-1/TT as a single conductor.
28. IMPROVISING VERTICAL ANTENNAS.
If mobility is not an immediate
requirement, you may wish to improvise a vertical antenna. The problem of
line-of-sight may be overcome by placing this antenna on top of a hill or
fastening it to a tree or pole to increase its height above surrounding
structures.
Figures 36 and 37 show ways to support improvised vertical
antennas. These antennas are relatively easy to prepare and emplace.
51
Previous Page
