MultiNav Pro+ BLE - does the RF front-end need any external filtering in noisy envs?

Ran into almost the exact same setup last year with a motor driver sitting about 40mm from the BLE antenna - ended up dropping a Murata SAFFB1G8KA0F0A BAW filter on the RF path and it made a noticeable difference in range consistency, especially once the motors were spinning under load. I'd also strongly recommend ferriting the VDD supply line to the module before you go chasing the RF path, because in my case about half the problem was conducted noise getting in through power rather than radiated stuff hitting the antenna directly. Honestly worth scoping the supply rail first so you know what you're actually fighting.

@Amy Smith yeah, the Murata BAW filter recommendation is solid — that specific part is a good match for the 2.4GHz band and the insertion loss is low enough that you won't be giving back much of what you gain in rejection.

 

One thing I'd add to what's already been said: the STM32WB07 front-end has decent built-in LNA and some filtering, but it's not really designed to survive a brushless ESC and a switching supply sitting that close. The module's receiver sensitivity spec assumes a reasonably clean RF environment, so if you're already seeing degraded range in the lab with everything running, you're probably not seeing the real ceiling — you're seeing a noise floor problem. Scope your VDD rail first like mentioned, and I'd also check whether your antenna has any ground plane separation from the motor driver's copper pours, because that's a sneaky one that kills range even when the supply looks clean.

 

If you end up going the BAW filter route, just make sure the RF trace between the module's RF pin and the filter is as short as humanly possible and matched — any impedance discontinuity there will eat your signal before the filter even gets a chance to help.

Peter's point about the supply rail is spot on - I wasted like two weeks tweaking antenna placement before I finally scoped VDD and realized the switcher was just hammering it with ripple. Once I got that cleaned up with a ferrite and a couple decoupling caps close to the module pins, half my "RF problem" basically disappeared on its own.

Both Peter and Luis nailed it - scope that rail first before touching the RF path, because you'll probably be shocked how bad the ripple is. That said, if you're still seeing issues after cleaning up power, the Murata BAW filter is a solid call, but also check your antenna keepout - I had a board where the ground plane encroached on the feedline and that alone was costing me like 4-5dBm of effective radiated power before I even had noisy neighbors to worry about.