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245U-E Wireless Ethernet Modem User Manual
15
Rev Version 2.24
Dipole and Collinear Antennas
A dipole or collinear antenna transmits the same amount of radio power in all directions—as such they are
easy to install and use. The dipole antenna with integral 15 ft (5 m) cable does not require any additional
coaxial cable. However, a cable must be used with the collinear antennas. To obtain maximum range,
collinear and dipole antennas should be mounted vertically, preferably 1 wavelength away from a wall or
mast (see Figure 11 for distances), and at least 3 ft (1 m) from the radio module.
Figure 11 Colinear/Dipole Antenna
Directional Antennas
Directional antennas can be any of the following:
• Yagi antenna with a main beam and orthogonal elements.
• Directional radome, which is cylindrical in shape.
• Parabolic antenna.
A directional antenna provides high gain in the forward direction, but lower gain in other directions. This
type of antenna 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, the Yagi elements should be vertical.
If the Yagi is transmitting to another Yagi, the elements at each end of the wireless link need to in the same
plane (horizontal or vertical).
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
