Weidmuller WI-MOD-945-E: 900Mhz Wireless Ethernet & Device Server v2.16 - Manual (Page 16)

Weidmuller Wireless Ethernet Modem & Device Server WI-MOD-945-E User Manual
Page 16 www.weidmuller.com Rev 2.136
antenna is not already shielded from lightning strike by an adjacent earthed structure, a lightning rod may be installed
above the antenna to provide shielding.
Dipole and Collinear antennas
A dipole or collinear antenna transmits the same amount of radio
power in all directions - as such that are easy to install and use. The
dipole antenna with integral 15 ft (5m) cable does not require any
additional coaxial cable; however a cable must be used with the
collinear antennas.
Collinear and dipole antennas should be mounted vertically, preferably
1 wavelength away (see drawing below for distances) from a wall or
mast and at least 3ft (1m) from the radio module to obtain maximum
range.
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 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 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”.
Wavelengths
900 MHz = 330 mm (1')
2.4 GHz = 130 mm (5")
5 GHz = 60 mm (3")
COLINEAR
ANTENNA
MAST
IF GROUND CONDITIONS
ARE POOR, INSTALL MORE
THAN ONE STAKE
MODEM
SURGE
ARRESTOR
(OPTIONAL)
COAXIAL CABLE
WEATHERPROOF
CONNECTORS WITH
“3M 23” TAPE
STRESS RELIEF
LOOP
PROVIDE GOOD GROUND
CONNECTION TO MAST,
MODULE AND SURGE
ARRESTOR
GND
1 wavelength
Directional
Antenna
45 o
Figure 3 – Dipole Antenna
Figure 2 – Collinear Antenna