No conductive items should be placed within 0.15" of the module’s top or
sides.
Do not route PCB traces directly under the module. The underside of the
module has numerous signal-bearing traces and vias that could short or
couple to traces on the product’s circuit board.
The module’s ground lines should each have their own via to the ground
plane and be as short as possible.
AM / OOK receivers are particularly subject to noise. The module should,
as much as reasonably possible, be isolated from other components on
your PCB, especially high-frequency circuitry such as crystal oscillators,
switching power supplies, and high-speed bus lines. Make sure internal
wiring is routed away from the module and antenna, and is secured to
prevent displacement.
The power supply filter should be placed close to the module’s V CC line.
In some instances, a designer may wish to encapsulate or “pot” the
product. Many Linx customers have done this successfully; however, there
are a wide variety of potting compounds with varying dielectric properties.
Since such compounds can considerably impact RF performance, it is the
responsibility of the designer to carefully evaluate and qualify the impact
and suitability of such materials.
The trace from the module to the antenna should be kept as short as
possible. A simple trace is suitable for runs up to 1/8" for antennas with
wide bandwidth characteristics. For longer runs or to avoid detuning
narrow bandwidth antennas, such as a helical, use a 50-ohm coax or
50-ohm microstrip transmission line as described in the following section.
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