Signal Propagation And Electromagnetic Field Distribution Indoor

It is very important to research the propagation of radio waves indoor.It not only proves basis of the layout of various communication systems,but also makes reference to the protection of electromagnetic pollution Indoor.What make the fluctuation phenomena of electromagnetic signal propagation are multipath effect and frequency selective fading.Besides,the type of wall, room layout, the different location of electrical equipment indoor and so on can also make an influence on the distribution of the signal level.I choose a graduate studio in new campus of Zhengzhou University as object of my study. I take all factors which play roles on signal propagation and electromagnetic field distribution indoor into consideration,such brick wall, reinforced concrete column, aluminum alloy window, iron security window,table with plastic block, iron air box,iron pipe. The signal frequencies which researches are 1MHz(AM signal),100 MHz(FM broadcasting),900 MHz and 1800 MHz(communication signals).The heights of transmitting antenna are 1.5m,1.7m (1MHz);1.6m (100MHz);1.51m (900MHz),1.67m (1800MHz).The sending antennas locate in both outside window and hall with horizontal polarization and vertical polarization.We have made third field surveying and recorded the radiation strength on the four frequencies in nine sampling location using Agilent spectroanalyzer.We also recorded the direction of receiving antenna when it received the maximal radiation strength.Considering the characteristic of environment indoor,I use the Finite Difference Time Domain (FDTD) to calculate.The electromagnetic parameters that need are specific inductive capacity, electrical conductivity and magnetic conductivity.The materials in real environment are composite materials,as to simplify the calculation,I regard the composite materials as dielectric slab with homotactic electromagnetic parameters.Special construction such as reinforced concrete column,I take weighted calculation and Fresnel formula to calculate the relative inductivity and electrical conductivity. I choose the electromagnetic simulation software XFDTD to make simulate.As to improve the precision of software model,I adjust the parameter of software model according to measured data,and make a good meliorate of software error. In view of the measured data and software model,I make analysis to signal propagation and electromagnetic field distribution indoor.