There is provided mechanisms for controlling average EIRP of a radio base station. A method is performed by a control device. The method comprises performing control of average EIRP of the radio base station according to a back-off power density control loop. In the back-off power density control loop, a beam width control parameter is used to vary the EIRP generated by an antenna array of the radio base station, whereby the average EIRP is selectively reduced based on the beam width control parameter.