ProSoft RadioLinx FH Series, Руководство пользователя

Страница: 37 / 151

Hardware Installation RLX-FHE, RLX-FHES, RLX-FHS ♦ RadioLinx FH
Frequency-Hopping Industrial Radio
ProSoft Technology, Inc. Page 37 of 151
November 25, 2008
5.1.4 Antenna Spacing Requirements
It is important to keep the radio's antenna a safe distance from the user. In order
to meet the requirements of FCC part 2.1091 for radio frequency radiation
exposure, this module must be used in such a way as to guarantee at least 20cm
(or more for high gain antennas- see antenna chart (page 37)) between the
antenna and the body. The FCC requires a minimum distance of 1mW *cm2
squared power density from the user (or 20cm, whichever is the greater
distance).
If a specific application requires proximity of less than 20cm, the application must
be approved through the FCC for compliance to part 2.1093.
The installer of this radio equipment must ensure that the antenna is located or
pointed in such a way that it does not emit RF field in excess of Health Canada
limits for the general population; refer to Safety Code 6, obtainable from Health
Canada.
To reduce potential radio interference to other users, the antenna type and its
gain should be so chosen that the equivalent isotropically radiated power (EIRP)
is not more than that required for successful communication.
5.1.5 Max Antenna Gain / Output Power
Note: FCC rules limit the antenna gain to 12dBi for point-multipoint networks using the RadioLinx
radio modems. All of the antennas approved for operation may be used for Point-to-Point
applications as they fall within the 24dB limit, however, antennas with gain greater than 12dBi
noted in the Approved Antennas table cannot be used for Point-Multipoint networks (broadcast,
Modbus or Ethernet). The calculations listed below illustrate these limitations.
The FCC transmitter power limit for this type of radio is 30dBm (or 1 watt). In
addition, safety considerations limit the output of this module to 250mW. To meet
the FCC requirements for emissions, the following restrictions on antenna gain
must be observed when establishing a radio network:
Point-to-Point network (page 18): max power 250mW / max antenna gain 24dBi
ƒ
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 1dB decrease in
output power below this reference point, the antenna gain can increase by
3dB.
ƒ
With the RadioLinx radio module's maximum output power of 250mW, the
maximum allowable antenna gain is 24dBi in a Point-to-Point application.
6dBi + (30dBm - 24dBm) * 3 = 24dBi
Point-Multipoint and Ethernet networks ( Broadcast (page 18), Modbus (page
21) and Ethernet (page 23) ): max power 250mW / max antenna gain 12dBi
ƒ
The transmitter power reference for a Point-Multipoint (Broadcast) network is
30dBm (1 watt) of output power with a maximum antenna gain of 6dBi.
ƒ
For each 1dB decrease of output power below this reference point, the
antenna gain can increase by 1dB.