1. An arrangement for heating a sample by microwave radiation, the arrangement comprising:a container having an inner space for accommodating the sample and having a bottom container wall;
a wave guide arranged to guide a microwave having an electric field direction;
a waveguide adapter being adapted to couple the microwave from the wave guide into the inner space of the container via the bottom container wall being oriented to be different from perpendicular to the electric field vector direction,
wherein the waveguide adapter has a recess below and close to the bottom container wall for accommodating equipment for at least one of:
monitoring at least one property of the sample;
stirring the sample.