Research Of Propagation Characteristics Of Vehicular Radar Based On 79GHz Frequency Band

With the widely application of the intelligent transportation system all over the world,as an important part to the improvement of safety when driving, vehicle radar has drawn much attention by major automobile manufacturers and numerous scholars. In order to ensure the safety when driving, modern auto safety technology involve two parts:the active safety and passive safety technology, and as an integral part of automotive active safety technology, the automotive radar can in time of danger forecast. It will affect the improvement of road traffic safety. Therefore, research on the improvement of auto safety initiative vehicle radar has practical significance.Vehicle radar based on 79 GHz frequency band has several advantages, the size of radar is smaller,a higher reliability and higher spatial resolution At present,most research based on 79 GHZ frequency band mainly focused on the design of 79 GHZ hardware transceiver systems, but there is little research on the characteristics of 79 GHz frequency band. According to the fact that vehicle-mounted radar based on the frequency band is easily affected by various environmental factors, and the vehicular radar shall be available all day long, wahtever the environment is. So the study of atmospheric environmental propagation characteristics and the propagation characteristics of band radar is of great significance to the further development and utilization of the band.In this paper, we first do an introduction on 79 GHz vehicle radar and the attenuation of millimeter-wave frequency band of the atmospheric in present research home and abroad. We focus on the characteristics of 79 GHz frequency band under different weather conditions,frog,rainfall,snowfall,to name a few. First of all, According to the recommendation presented by International Telecommunication Union(ITU),the models proposed by ITU-R has been studied,the equivalent path length and the unit distance of rain attenuation are described. Simulation of the comparison with the frequency band in different rainfall intensity, different distance and the corresponding degree of polarization are discussed. Attenuation effect of rain attenuation on this frequency band has been proposed. At the same time, this paper contains the comparisons of different fog centigrade,snow intensity analyses. The factors that affect the attenuation of the 79 GHz frequency band are obtained, and the attenuation of the frequency band in the weather conditions is quantitatively analyzed by simulation.At the same time, in order to know radar performance based on 79 GHz frequency band under different weather conditions,namely sunny weather,different rainfall intensity,snowfall intensity. By the introduction of the composition and operation principle of millimeter wave radar,the affect of 79 GHz radar performance in rain condition is mainly discussed. 79 GHz vehicle radar in different weather conditions are simulated and analysised,radar maximum detection range of change and the affection of radar equation,detection probability of radar has been analyses.At last,a model of V2V(Vehicle-to-Vehicle) communication is established. Based on the geometric link model,assume that 79 GHz as the main tool for transportation in intelligent system,the Doppler shift is studied, path loss based on the model is the derived, and the multipath is analysesed.Results shows that the influence of rainfall is the greatest of all the weather condition we discussed,and also the rainfall affect bigger than all other weather conditions in the performance of 79 GHz millimeter wave radar. This research provides a certain theoretical support for the further development and utilization of 79 GHZ frequency band.