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Antenna Installation
Safety Considerations
WARNING!
INSTALLATION OF ANY ANTENNA NEAR POWER LINES IS DANGEROUS
Warning
: Do not locate the antenna near overhead power lines or other electric light or power circuits,
or where it can come into contact with such circuits. When installing the antenna, take extreme care not
to come into contact with such circuits, because they may cause serious injury or death.
Overhead Power Line Safety
Before you begin working, check carefully for overhead power lines in the area you will be working.
Don't assume that wires are telephone or cable lines: check with your electric utility for advice.
Although overhead power lines may appear to be insulated, often these coverings are intended only to
protect metal wires from weather conditions and may not protect you from electric shock Keep your
distance! Remember the 10-foot rule: When carrying and using ladders and other long tools, keep them
at least 10 feet away from all overhead lines - including any lines from the power pole to your home.
Mounting Considerations
When planning the location of your antenna, consideration should be given to the height, location of
suitable support structures and feedline positioning and length.
Generally speaking, dipole antennas should be mounted as high as possible for best performance.
Antenna height will affect the exact resonance point, radiation pattern, and takeoff angle. The higher the
antenna, the lower the takeoff angle to the horizon, which increases the effective range of the antenna.
For DX, the minimum height above ground should be 1/2 to 1-wavelength at the lowest operating
frequency. On the low bands, this height becomes impractical for most hams. For example, an 80m
dipole at 70 feet is about 1/4-wavelength above the ground. This antenna would be good for local and
short distance communications, but not optimal for DX, due to the high takeoff angle and ground
absorption. A 40 Meter dipole at 70 feet is approximately 1/2-wavelength high and is likely to be good
for DX and less optimal for local or short range communications. For more information on antenna
design, feedline and radiation angles, consult a reliable text such as the
"
ARRL Antenna Book
"
which is
available from DX Engineering.
