Experimental Studies of Electromagnetic Wave Attenuation by Flame and Smoke in Structure Fire

Attenuation of electromagnetic waves in the fire scene is an important issue when the stability of wireless communication is concerned, especially in fire rescue scenarios of high-rise buildings. Therefore, it is of importance to study the effects of flame and smoke on the attenuation of electromagnetic waves in structure fire. In this article, the influence of flame was studied through using alcohol as fuel. Different types of fuels were used to produce different concentrations of smoke. Different ranges of electromagnetic wave frequency from 350 MHz to 400 MHz were also used to investigate the frequency-dependent properties of the attenuation effect. The results show that flame itself does not have significant effects on the electromagnetic wave attenuation, but smoke plays an important role. Smoke from diesel fuel results in larger signal attenuation than other fuels, with attenuation of 1.16 dB at 300 MHz. The relationship between the concentration of smoke and signal attenuation follows the first-order exponential function. It also indicates that electromagnetic wave attenuation is frequency-dependent. The attenuation is 5.43 dB at 360 MHz when the smoke concentration is 20 dB/m, but only 0.26 dB at 400 MHz. It is suggested that a frequency-dependent assessment should be considered for investigating the reliability of the wireless communication system in structure fire in high-rise buildings.