5.2

Layout recommendations

5.2.1

STM32WB5MMG placement

The embedded antenna manufacturer of the STM32WB5MMG recommends to place the module on the

application board as shown below.

This position allows the antenna to work to its maximum performance. If it cannot be placed as recommended

above, the application board performance is be reduced. This does not, however, prevent correct operation.

5.2.2

Enclosure effects

Product casing properties must be also considered when designing an RF-enabled product as the following list

illustrated;

•

Conductive enclosure in close proximity (in far-field) of the antenna reflects the radiating signal and thus

decreases the transmitting / receiving power. If there has to be a metal part in the enclosure, consider a

frame rather than a box.

•

Conductive enclosure in the near field affects the impedance of the antenna, also the resonant frequency. A

metal case must not be in the near field. The threshold between near and far-field is provided in Figure 5.

•

Plastic enclosures can be close to the antenna, but must not touch it. Contact between the casing and the

antenna may influence the tuning of the resonant frequency and impedance matching.

•

The proximity of the human body attenuates the TX and RX signals due to a certain amount of water

content. Any contact may untune frequency and impedance matching.

STM32WB5MMG

Layout recommendations

DS13252 - Rev 1

page 10/31