Siemens SIMATIC NET System Manual page 234

SCALANCE network components
4.6 SCALANCE W components for the Industrial Wireless LAN
Two further related properties are important for any antenna:
● Radiation characteristics
The radiation characteristics describe how strong the directionality of an antenna is. You
have three options:
– Omnidirectional (omnidirectional antennas)
– Directional (directional antennas)
– Sectoral (sector antennas)
● Antenna gain
The antenna gain is the characteristic value for the directionality of an antenna. This
parameter is obtained by comparing the maximum radiated power of the antenna with the
power of an isotropic radiator. The antenna gain
following formula:
G = 10 * log (max. power density antenna / max. power density of an isotropic radiator)
Antennas with multiple connectors: Dual or MIMO antennas according to IEEE 802.11n
Dual antennas are antennas with two connectors. These are integrated in an antenna
housing as two individual antennas offset by 90° from each other or have a suitable
clearance to each other. These antennas can be used to transmit two data streams at the
same time.
MIMO antennas are antennas with three connectors. They contain three individual radiators
combined in one antenna housing and operating either in different polarization planes (0°, +/-
45°) or with a suitable clearance between them. The MIMO antennas can transmit three data
streams simultaneously making use of multipath propagation.
Transmitting multiple data streams increases the data throughput while at the same time
making data transfer more reliable.
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Radiation is uniform in all directions of a spatial plane (circular horizontally or
vertically, depending on the position of the antenna).
Radiation is predominantly in one direction in which the electromagnetic waves are
transmitted with higher intensity. In the other spatial areas, the field strength is
correspondingly weaker. The reach of the wireless signal increases through a
narrower angle. The disadvantage of directional antennas is that they need to be
exactly oriented towards the partner.
Sector antennas are directional antennas with a larger opening angle. It lies between
30 and 120 degrees horizontally and 5 and 10 degrees vertically. As a rule several
sector antennas are positioned at a location to ensure full 360° coverage.
G
is calculated in dBi according to the
System Manual, 09/2019, C79000-G8976-C242-10
Industrial Ethernet