In an embodiment, an apparatus includes a detector and a range finder. The detector is configured to determine a direction to a target in response to a signal received from the target, and the range finder is configured to determine a range to the target in response to the direction and independently of an amplitude of the signal. For example, such an apparatus (e.g., a computer-based apparatus) may be disposed on tactical fighter aircraft, and may be able to range (e.g., azimuth range or slant range) a target passively even if an accurate measure of the amplitude of the signal received from the target is unavailable.