Hello! I'm working on a custom PCB that uses the STM32WB1MMCH6TR module, which was chosen specifically because of its integrated antenna. Unfortunately, with the first prototypes I'm getting extremely poor range with BLE, usually <-80 dBm even just a few inches away. This makes it near impossible to communicate with it from any useful distance. I made sure to turn the transmit power (CFG_TX_POWER in CubeIDE) all the way up to 6dBm, but it didn't help with the signal strength.
I was not able to find much information on designing a PCB around this module, so I just went based off the keep-out zone that came with the supplied footprint on Digikey. I suspect that there may be components too close to the antenna side of the module, but I want to ask for advice before ordering the next revision. Thank you!
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Accepted Solutions
I've solved the issue. The STM32WB1MMC datasheet is very vague when it comes to PCB layout requirements, and fails to mention that the antenna side of the module needs to be up against the side of the PCB. I ended up using a Dremel tool to cut off that corner of the PCB, and am now getting >60dBm RSSI. In the next revision, I'll just place the STM32 a few mm to the left so that it's against the side of the PCB.
I've solved the issue. The STM32WB1MMC datasheet is very vague when it comes to PCB layout requirements, and fails to mention that the antenna side of the module needs to be up against the side of the PCB. I ended up using a Dremel tool to cut off that corner of the PCB, and am now getting >60dBm RSSI. In the next revision, I'll just place the STM32 a few mm to the left so that it's against the side of the PCB.
