Abstract: The invention relates to portable mobile communication device. The system according to the invention measures the power transmitted by the mobile communication device and the reflected power returning from the antenna. From these, the system calculates various parameters, for example, the short-term average value, the cumulative sum of transmitted power used during a call and the proportion of power reflected back. The user may set the limit values which he requires for these parameters, and the system will issue an alarm when these are exceeded. If the user so desires, the system may also continuously display the value of a desired quantity. With the aid of the system according to this invention, the user may monitor the benefit of different positions and ways in which the appliance is used and the power consumption of the mobile communication device in different situations, and thus avoid unfavorable operating situations and methods.