Methods and apparatus are provided for localizing a source of a set of radio signals, such as radio signals received from an RFID tag at various locations. A source of a set of radio signals (such as radio signals received from an RFID tag at various locations) is localized by obtaining a plurality of radio signals in the set from a different location in an environment; determining a magnitude and received location for each of the plurality of radio signals; determining a direction for each of the plurality of radio signals by comparing each given radio signal to other radio signals in the set; and determining a location of the source of the set of radio signals by determining an intersection of the direction for each of the plurality of radio signals. The direction for each of the plurality of radio signals optionally comprises a net directional vector determined using a weighted circular mean.