Effects of shipboard compartment fuel fire and fire extinguishing on RF signal propagation in the 24 GHz ISM band

Abstract

The objective of this research was to quantify the effects of fuel fire and the follow-on fire extinguishing actions on wireless shipboard communications in the 2.4 GHz ISM band. Directional and non-directional antennas with horizontal and vertical polarization, and a PC-controlled scalar network analyzer, were used onboard ex-USS SHADEWELL to measure the attenuation of 2.4 - 2.485 GHz signals transmitted through diesel and heptane fire, water mist created by the fire extinguishing system, and subsequently developed steam. A MATLAB code has been used to analyze the data statistically. The attenuation for directional antennas exhibits relatively small variations wit time and frequency, but fire and the follow-on fire-extinguishing phases create sever non-stationary frequency selective fading for non-directional antennas. Therefor standard communication techniques effective against frequency selective fading (non stationary but slowly varying with time) are recommended for use with communication systems intended for shipboard indoors use. Even in normal conditions, without fire, water mist, or steam, we have determined that frequency selective fading would be problem for non-directional antennas used in shipboard compartments and thus a system with anti-fading ca ability should be considered for ship board use