Design Of The Novel Antennas For Confined Spaces And Research On The Characteristics Of Radio Wave Coverage

In the confined space such as tunnels and mines, wireless communication plays an important role to ensure the safely operation of vehicles and personnal safety. However, quality of communication is difficult to guarantee, because the dimension of confined spaces is narrow, the electromagnetic environment is complicated and the path losses of radio wave propagation is great. Antenna has a critical impact on radio coverage. The previous research on the characteristics of radio coverage in confined space mainly concern about plane wave, less considering the influence of antenna characteristics. For these problems in previous study, this paper selects tunnel as the object, and combines normalized pattern function of antenna and ray tracing method to build a model. The impact of different beam shapes on radio coverage in confined space is analyzed. This paper extracts the normalized pattern functions of Yagi antenna and planar array antenna, discusses the influence of structural parameters on characteristics of radio coverage in confined space. An optimization scheme of antenna is proposed, which improves the performance of antenna. Analyses the influences of environmental factors and antenna operation frequency on characteristics of antenna radio coverage.The main work and the innovation of this paper are summarized as follows:1. The effects of different antenna beam shapes on radio coverage in tunnel are studied. Analyses the effect of four patterns which have same half-power beamwidth but differently shaped beam on radio wave coverage, discusses the radio waves fading caused by different beam emission position and half-power beamwidth. By comparing the path losses curves of the radio wave propagation, we can find out that the rectangular beam is more suitable for radio coverage in confined space because of its high directivity.2. The structures and radiation patterns of Yagi antenna and planar array antenna which are widely used in engineering are studied, and the impacts of antenna structures on characteristics of its radio propagation in confined space are analyzed. By optimizing the structure of the antenna, its performance on radio coverage in tunnel is improved. Analyses the effect of side-lobe level which has same main lobe on the characteristics of radio coverage in tunnel.3. Using Gaussian beam as transmitting beam, the influences of environment such as the tunnel size and wall parameters (permittivity, conductivity) on the characteristics of radio coverage is studied in the condition of same antenna radiation parameters. The influence of operation frequency of antenna on its characteristics of radio coverage is studied, which provides a reference on the use of increasingly rich communication bands in confined space.