915 wire dipole - Barrett P/N BC91500
Single frequency wire dipole antennas, spot-tuned to the required operating frequency(s),
are the most efficient antennas for use in HF base stations. They are simple to install and
have a relatively narrow bandwidth.
Dipole antennas should be mounted at least 1/2 wavelength from the ground. Dipoles may
be mounted either between two towers or in an inverted "V" configuration (requires only one
mast). As a guide, when installing the masts, the length between insulators of a half wave
wire dipole is 142/(frequency of dipole in MHz) metres. To this an allowance should be made
for extra insulators and halyards.
i.e. a 3.7MHz dipole - length between the insulators = 142/3.7 =38.38 metres.
Wire dipoles supplied by Barrett Communications are pre-cut to a specified frequency but
have adjustable ends. These adjustable ends allow fine tuning for optimum VSWR during
installation. To fine tune a dipole install the antenna in its final position and check the
antenna VSWR. Should the VSWR be greater than 1.5:1 the antenna will require
adjustment.
Single frequency wire dipole
Single frequency wire dipole in an
inverted "V" configuration
BARRETT 950 HF TRANSCEIVER
PAGE 104
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