RIM 1802G, Руководство интегратора

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Chapter 7: Antenna selection
64 RIM OEM Radio Modem for GSM/GPRS Wireless Networks
Shielding
The RIM 1902G or RIM 1802G electrical design provides high immunity to radio frequency (RF)
noise, also called electromagnetic interference (EMI). The metal casing also acts as a shield that helps
to minimize the effect of RF interference that originates in the computing device to which it is
attached. The metal casing also prevents the RIM 1902G or RIM 1802G from emitting RF energy into
the computing device and disrupting the computing device’s operation.
Consequently, you do not need to provide any additional RF shielding between the radio modem
and a computing device, unless the environment contains an extreme level of RF noise. In fact,
additional RF shielding is less important than making sure that the radio modem’s power supply is
free of high-frequency electrical noise.
The antenna must be positioned so that the radiated energy is directed away from the computing
device. If your application does not permit this positioning, RF shielding might be required between
the antenna and the computing device.
Note: Circuits with a high impedance, and sensitive analog circuits, are especially vulnerable to nearby radio
frequency emissions, and might need to be shielded. Circuits such as cathode ray tubes (CRTs) and LCD display
drivers are most often affected.