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Hardware Integration Guide
Determining the Antenna's Location
3.2.2.
Consider the following points when deciding where to place the antenna:
Antenna location may affect RF performance. Although the module is shielded to prevent
interference in most applications, the placement of the antenna is still very important—if the
host device is insufficiently shielded, high levels of broadband or spurious noise can degrade
the module's performance.
Connecting cables between the module and the antenna must have 50Ω impedance. If the
impedance of the module is mismatched, RF performance is reduced significantly.
Antenna cables should be routed, if possible, away from noise sources (switching power
supplies, LCD assemblies, etc.). If the cables are near the noise sources, the noise may be
coupled into the RF cable and into the antenna.
3.3.
RF Desense Sources
Common sources of interference that may affect the module's RF performance (RF desense) include
Power supply noise
Can lead to noise in the RF signal
Module power supply ripple limit <= 100 mV
Interference from other embedded wireless devices
Any harmonics, sub-harmonics, or cross-products of signals that fall in the module's Rx
range may cause spurious response, resulting in decreased Rx performance.
Tx power and corresponding broadband noise may overload or increase the noise floor of
the module's receiver, resulting in RF desense.
Severity of interference depends on proximity of other antennas to the module's
antennas.
Host electronic device-generated RF
Proximity of host electronics to the module's antenna can contribute to decreased Rx
performance.
Some devices include microprocessor and memory, display panel and display drivers,
and switching mode power supplies.
Note:
In practice, there are usually numerous interfering frequencies and harmonics. The net effect can
be a series of desensitized receive channels.
4112719
Rev 2.1
1 Hz–100 kHz
p-p
January 07, 2013
RF Integration
13
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