User's Guide

7.3.1 Small Board Size Recommendations for Good RF Performance
Figure 7.4. Reference Design for Small PCB Sizes
Note: Spaces filled in black represent metal keep-outs on the PCB in the figure above.
• Required WFM200 Board size in X = 17.5 mm ± 3 mm of metal.
• Required WFM200 Board size in Y = 55 mm ± 3 mm of metal.
• PCB may be slightly larger to account for PCB edge routing.
•
Area for optimum performance is 55 mm z 17.5 mm = 963 mm
2
• The recommended board width is Y= 55 mm. Board widths up to Y= 65 mm still meet regulatory certifications but will result slightly
degraded RF performance.
• Board size smaller than 17.5 mm x 55 mm will have lower antenna efficiency, more variation in return loss, and may require TX
power to be reduced to meet RF performance specifications.
• If the carrier board width Y < 45 mm, then better RF performance can be achieved if the WFM200 module is shifted to the north, i.e.,
ensure larger (close to 22.5 mm) PCB metal width on the antenna clearance area side of WFM200. Otherwise, center pins 49 and
48 vertically.
• The center of pin 49 is 1.8 mm from the metal edge.
• Connectors are only allowed in the middle 18 mm adjacent to the occupied area.
• Components may be placed north and south of occupied area.
• The PCB must have continuous GND fill around the edge inboard to at least 1.8 mm with the exception of the occupied area as
shown.
• Cables must exit from the connector area directly away from the designated occupied area.
UG395: WFM200 Hardware Design User's Guide
Layout Recommendations
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