Testing And Research Of2.4GHz Wireless Signal Propagation In Underground Mine Confined Space

With development of wireless communication technology, the2.4GHz has been appliedin the confined spaces.Due to the severe environment for wireless signal in confinedspaces,and difficulty to cover2.4GHz signal, it has significant meaning to research wirelesspropagation in order to construct2.4GHz wireless communication system in mine.Base on current situation of the wireless signal coverage measurement system, we studythe mathematical laws of strength and distance of confined spaces wireless signal throughusing waveguide-mode theory and wireless transmission characteristic of electromagnetictheory of geometrical-optics theory.then propose the design of confined spaces2.4GHzcoverage measurement. we adopt a very precisive voltage-controlled oscillator as frequencysignal source, a USB bus based portable power meter as the wireless signal strengthmeasurement equipment. complete the construction of testing system for confined spaces of2.4GHz wireless signal. we get the strength data from different roadway in mine after testingvice flat hole of underground coal mine, transport pan and unmanned workplace at differentroadway.Base on free space propagation model as the, this paper combined with the specialenvironment of underground, through use of waveguide mode theory and geometrical-optical theory of characteristics of electromagnetic wireless transmission to establishunderground wireless transmission channel model. We analyze sample data and study the2.4GHz signal propagation characteristics in coal mine and confined spaces throughMATLAB. At30m from the point source,the signal strength is decline, at30-120m wirelesssignal strength fluctuates within30db, it has big difference between actual measurement dataand propagation regularity which been obtained from waveguide and geometrical opticsmethod. it In order to theoretical foundation for2.4GHz wireless network covering in mine confined spaces.