• Doublet Antenna
This type of antenna is suitable for reception of a specific
band.
The relation between the overall length "L" and the tuned
frequency is:
7-2. ANTENNA AND GROUNDING
7-2-1. Antenna
The following describes various antenna types and their
installation.
• Long Wire Antenna
This is the simplest antenna, using about 30 – 100 feet
(10 – 30 m) of wire installed between poles, trees or
other convenient supports. The antenna wire should be
heavy 8 gauge vinyl insulated, stranded wire or 4-gauge
copper wire or copperweld. This type of antenna must be
installed horizontally to a length of 60 feet (20 m) or more,
and be positioned as high as possible. Note that it should
be as far away as possible from AC power lines, buildings,
trees and other objects.
Fig. 7-1 shows an inverted L antenna. Other antenna
types such as sloping, vertical, etc. are also possible.
A long-wire antenna, when installed in an open area, is sui-
table for all-band operation.
This antenna is directional. Signal strength is maximum
when the antenna is at a right-angle (broad-side) to the de-
sired signal and the frequency for which the antenna is
cut. It must be used with a 75-ohm coaxial feeder. (See
Fig. 7-2)
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