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920MHz Band Wireless Device (Korea) USERS MANUAL EM-9121 Rev. 1
9. INSTALLING WIRELESS DEVICES
Carefully read through the following notes before installing wireless devices.
9.1 RECOMMENDED INSTALLATION LOCATIONS
In order to realize data communication in satisfactory radio wave conditions, wireless devices shall be installed under the following
conditions.
1) Install devices as high as possible to avoid obstacles that interrupt radio wave.
2) When a metal plate is present behind a wireless device, the backward radio wave from the device may possibly become a noise
reverberatively or hardly reach other devices installed behind. Avoid such a location as much as possible. When it is unavoid-
able, install an antenna as far from the metal plate as possible.
3) Install wireless devices in unfrequented places with good visibility.
9.2 INSTALLING ANTENNAS
The radio wave state may vary greatly depending on the directions and installation locations of antennas. When it is poor, change
their directions and locations as shown below.
1) Match the polarization planes of a parent and child devices. Install an antenna with its direction perpendicular to the ground
because its directionality is omnidirectional to the horizontal plane.
(Different polarization
planes)
NG
OK
OK
OK
(Different polarization planes
and directionalities)
NG
(Different polarization planes
and directionalities)
NG
(Different polarization planes
and directionalities)
NG
(Different polarization
planes)
NG
(Different polarization
planes)
NG
Figure 9.1 Polarization plane of antenna
2) Secure a Fresnel zone.
3) A sleeve antenna is movable in the range of 90°. Adjust the installing direction of the antenna and its angle. When changing the
angle, turn the antenna clockwisely so that the antenna will not slip off or be loosened.
4) In case of a rooftop antenna, extend a cable (2.5 m) to change the installation location of the antenna.
5) When using a rooftop antenna, fix the magnet base to a metal plate (recommended dimensions: 500 mm × 500 mm or more).
6) Make sure that there is no antenna used in a different network in the neighborhood. If any, secure the distance of at least 2 m
or more away from such an antenna.
Note: When using a rooftop antenna, do not force the cable to bend beyond the acceptable bending radius of 3 cm.