- 10 -
on antenna design, feedline and radiation angles, consult a reliable text such as the
"ARRL Antenna
Book"
which is available from DX Engineering.
Support Line
The Center-T’s top hole is used for the attachment of a UV protected messenger rope line that is
used to provide support for the antenna wire and feedline. The use of the messenger line, which is
strongly recommended when a DX Engineering balun is attached, will reduce the stress on the
element wires and keep the antenna from stretching over time, which will change its resonant
frequency.
When using trees for support, you may want to use counter weights that will allow the rope to move
when the trees sway in the breeze to avoid stretching or breaking your dipole. For more hints,
consult a reliable text such as the "
ARRL Antenna Book
" which is available from DX Engineering.
Ideally, the messenger line should attach to the same structure used for the dipole, only above it,
forming at least a 30 degree angle between the dipole and the messenger line to support the antenna.
See
Figure 14
.
Figure 14 –
Flat Dipole Installation using a Messenger Line
UV protected rope is used for the messenger line by forming a loop at the mid-point of the rope.
Push the loop through the Center-T top hole, and pull the rest of the rope through the loop.
See
Figure 15
.
Figure 15 – UV protected Rope Loop for Messenger Line
The excess rope can be used to attach the antenna end insulators to the support structures. Use the
same structures used by the messenger line if possible. The ends of the rope should be cauterized
with a small flame to prevent the rope braid from fraying.
