Reference Guide

HUM-A-900-PRO Trace Layout Guide
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2.3. Vertical Mount RP-SMA connection
The Vertical Mount RP-SMA RF connection is approved only for operation at the Low RF Data
Rate (19.2kbps) This design uses a PCB microstrip to connect the HUM-A-900-PRO module’s
Antenna castellation to an edge mount reverse polarity SMA connector Linx Part number
CONREVSMA001. A four layer PCB is used for this design. The Top layer 14mil wide RF trace
and Mid-Layer 1 ground plane form an RF microstrip.
Table 3 shows the required host PCB layer stackup for the Vertical Mount RP-SMA
connection. This layer stackup must be matched precisely including material type,
dielectric constant, dielectric thickness, and copper thickness.
Figure 3 shows the trace dimensions that must be followed precisely, including trace
width, routing, and RF matching components. A 15pF series capacitor (Murata
GRM0335C1H150GA01D) is located between the module and the RP-SMA connector for
RF matching. A 10mil wide microstrip connects the center post of the RP-SMA connector
to a 100nH inductor (Bourns CW201212-R10J) for RF matching.
The Ground plane on Mid-layer 1 must not have any cutouts in the area under the RF
trace, in the area between the module and the connector, or under the RF matching
components.
Table 3 - PCB Stackup for Vertical Mount RP-SMA Connection