Development of a 94GHz passive millimeter wave imaging system for target detection in haze and smoke

A 94GHz passive millimeter wave (PMMW) imaging system is designed, prototyped and tested for target detection in haze and fog. To compact the system size and increase the scan area and speed, continue azimuth with step elevation (θ-φ) scanning is used here. Center frequency of the detected signal is 94GHz and the bandwidth is +/-2GHz. To increase the sensitivity and eliminate noise, an instrumentation amplifier and an active low pass filter with 10Hz cutoff bandwidth are adopted in this system. Test conducted in a sheath room shows that this system is suitable for detecting target in thick smoke.