Probably hardware-related. Good, or at least thouroughly-tested and characterized, design can make or break high-frequency RF applications. Check out the PCB g

Probably hardware-related. Good, or at least thouroughly-tested and characterized, design can make or break high-frequency RF applications. Check out the PCB guidelines for the popular NRF51822 Bluetooth tranceiver: https://devzone.nordicsemi.com/blogs/655/general-pcb-design-guidelines-for-nrf51/ https://devzone.nordicsemi.com/blogs/655/general-pcb-design-... It barely scratches the surface, and in reality there will always be some trial and error as other nearby circuit elements can cause unpredictable interference or feedback. But it's a lot more finnicky than laying out an Arduino board.