Embodiments of the present invention is directed to a method and system for use of ranging MW to reduce dual (MW/PIR) intrusion detector false alarms. A Doppler microwave system may be provided that is capable of detecting an object range and adjusting the sensitivity of the PIR detector to account for object size and range. Multiple range limited MW stages may be configured for different ranges to determine the general range of the moving object. Based on signal levels present on these MW stages, an approximate object range is determined. The sensitivity of the PIR is then adjusted based on a PIR sensitivity vs. object range function that is optimized to alarm on humans and ignore small animals and insects.