Fire detection by low-cost microwave radiometric sensors

This paper discuss the possibility to detect a fire exploiting microwave radiometric sensors. In particular the experiences carried-out at the University of Duisburg-Essen, Germany and at the University of Perugia, Italy, are described. At the University of Duisburg-Essen a multi-frequency radiometer, capable of full 2-40 GHz coverage, has been developed. This sensor has been used to characterize the microwave emission of fire as a function of shape and of burning materials. In addition, the response of this microwave radiometer has been compared with those of standard (i.e. CO and CO₂) fire sensors. At the University of Perugia, instead, a portable 12.65 GHz radiometric sensor has been developed. This frequency has been chosen in such a way as to balance a good obstacle penetration capability with a reasonable antenna size. To keep low the radiometer cost, commercial TV-SAT components have been adopted along with a noise-adding (switch-less) calibration architecture. Such a sensor is able to detect small fires (filling factor below 1%) while being characterized by a component cost less than $1800.