Hi
I am developing for the nRF51822 a 4 layer print with a power and a ground plane in the inner layers. I will be using a balun from Johanson Technology (2450BM14E0003) with the Nordic PCB antenna (from the USB dongle).
The product specification of the nRF51822 says that I need to put a keep-out area under the antenna matching circuitry. Is this keep-out also needed when using a balun? Or can I both have a power and a ground layer there?