Abstract: A microwave range detector system for determining the range of a moving object in a monitored area includes: a microwave antenna for focusing microwave energy in the area to be monitored; means for selectively generating microwave signals at a first microwave frequency and at a second microwave frequency for transmission by the antenna; microwave detector means, responsive to the microwave signal at the first microwave frequency and the return signal at the first microwave frequency from a target in the monitored area, for generating a pair of Doppler frequency signals with a fixed-phase relationshp, and responsive to the microwave signals at the first and second microwave frequencies and to the return signals at the first and second microwave frequencies, respectively, from a target in a monitored area, for generating a pair of Doppler frequency signals with a variable-phase relationship; direction decoder means, responsive to the Doppler frequency signals with the fixed-phase relationship, for determining w