Direction finding using signal power

Apparatus for determining incident angles of RF signals received by an antenna array comprising a plurality of antennae, the apparatus comprising:

• a direction finding (DF) signal module configured to generate a plurality of DF signals based on antenna signals received from the antenna array, wherein the DF signal module is configured such that each DF signal corresponds to a respective antenna array element and each antenna array element corresponds to one or more antennae;
• a spectrum obtaining module configured to receive the plurality of DF signals and to generate a corresponding plurality of DF spectra, each DF spectrum generated by converting a corresponding DF signal into a power spectrum, wherein each DF spectrum comprises measured values of power at two or more given respective frequencies;
• an antenna array information store configured to hold information about the configuration of the antennae in the antenna array and the antenna gain patterns corresponding to the antenna array elements;
• an incident angle determining module configured to calculate an incident signal angle for each frequency based on the measured values of signal power at the frequency and the configuration of the antennae in the antenna array and the antenna gain patterns corresponding to the antenna array elements.