FIG. 3 shows a flow chart of a method for determining an execution frequency for a foreign object detection method of a WLC system/transmitter according to an embodiment. In the method 300, in step 310, a power level value of transmitted wireless energy is determined, and in step 320 a foreign object detection method frequency is adjusted on the basis of said power level value of the transmitted wireless energy.

FIG. 4a shows some examples of FOD detection frequencies as a function of TX power according to an embodiment. 400 is an exponential graph of FOD frequency as a function of a TX power level, 420 is a periodic graph of FOD frequency as a function of a TX power level and 430 is a linear graph of FOD frequency as a function of a TX power level. In some example embodiments, the FO detection frequency may depend on the TX power by an increasing function. That is, when a WLC transmitter increases the TX power, it may also increase the FO detection frequency accordingly.

FIG. 4b shows some examples of lengths of intervals between adjacent FODs as a function of TX power according to an embodiment. 440 is an exponential graph of length of FOD intervals as a function of a TX power level, 450 is a periodic graph of length of FOD intervals as a function of a TX power level and 460 is a linear graph of length of FOD intervals as a function of a TX power level. In some example embodiments, the time interval between adjacent FO detections may depend on the TX power by a decreasing function. That is, when a WLC transmitter increases the TX power, it may also shorten the FO detection interval accordingly.