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2.2.2 Directional antennas.
Directional antennas can be
… a Yagi antenna with a main beam and orthogonal elements, or
… a directional radome, which is cylindrical in shape, or
… a
parabolic
antenna.
A directional antenna provides high gain in the forward direction, but lower gain in other
directions. This may be used to compensate for coaxial cable loss for installations with
marginal radio path.
Yagi antennas should be installed with the main beam horizontal, pointing in the forward
direction. If the Yagi is transmitting to a vertically mounted omni-directional antenna, then
the Yagi elements should be vertical. If the Yagi is transmitting to another Yagi, then the
elements at each end of the wireless link need to in the same plane (horizontal or verti-
cal).
Directional radomes should be installed with the central beam horizontal and must be
pointed exactly in the direction of transmission to benefit from the gain of the antenna.
Parabolic antennas should be mounted as per the manufacturer’s instructions, with the
parabolic grid at the “back” and the radiating element pointing in the direction of the
transmission.
Ensure that the antenna mounting bracket is well connected to “ground/earth”.
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