User's Manual

OS2400 Radio Module Exhibit 21: User Manual 3 FCC ID: OQ7OS2400
6
Max Antenna Gain / Output Power
NOTE:
All of the Locus, Inc., approved antennas meet the Point-to-Point antenna gain / output
power emissions requirement. The approved antennas with gains greater than 12dBm,
however, can only be used for point-to-point networks and may not be used for point-
multipoint networks. The calculations below illustrate this limitation.
The FCC transmitter power limit for this type of radio is 30 dBm (or 1 watt). In addition,
to ensure safety, the output of this module is limited to 250mW. To meet the FCC
requirements for emissions, the following restrictions on antenna gain must be adhered
to when establishing a radio network.
Point-to-Point network:
max power 250 mW / max antenna gain 24 dBi
?? The transmitter power reference for a Point-to-Point network is 30dBm (1 watt) of
output power with an antenna gain of 6dBi. For each 1 dB decrease in output
power below this reference point, the antenna gain can increase by 3 dB.
?? With the OS2400 radio module’s maximum output power of 250 mW, the
maximum allowable antenna gain is 24 dBi in a Point-to-Point application.
(30dBm - 24dBm) + (6dBi * 3) = 24dB
Point-Multipoint network:
max power 250 mW / max antenna gain 12 dBi
?? The transmitter power reference for a Point-Multipoint network is 30 dBm (1 watt)
of output power with a maximum antenna gain of 6 dBi.
?? For each 1 dB decrease of output power below this reference point, the antenna
gain can increase by 1 dB.
?? The OS2400 radio module has a maximum output power of 250 mW or 24 dBm.
Therefore, the maximum allowable antenna gain at full output power is 12 dBi in
a Point-Multipoint application.
(30dBm -24dBm) + 6dBi = 12dBi