| In recent years, with the rising level of economy, the increasing number of vehicles has lead to the environmental degradation in traffic. Social demands for promoting road traffic safety are enhancing, automotive radar emerges as time require. As an indispensible part of Adaptive Cruise Control(ACC) systems, it can detect the surrounding obstacles and maintain a specified spacing betweenthe two vehicles. Based on the commercial background, research on the antenna system of automotive radar has been proposed.In this paper, we propose a millimeter-wave microstrip array antenna module for automotive radar sensors. The antenna which include transmitting antenna and receiving antennas was designed operating at 24 GHz and intended for obstacle detection and short-range automotive applications. To meet the practical commands,different gain, beam width and shape imply different requirements on the transmitting and receiving antennas.Primarily, a single patch is designed to be a rectangular patch with a U-slot on both sides of feed line, which can extend the bandwidth of antenna. Then, combined with the antenna array synthesis theory, the design of antenna array is conducted. The transmitting part was implemented by a 8×6 microstrip array antenna and improved with the concern of nonhomogeneous weights for amplitudes excitation. High gain transmitting antenna can amplify the radiation power and fulfill required transmission distance. Meanwhile, the beam should be narrow in order to avoid thedisturbance on the neighbor lanes. The receiving part consisted of two independent 8×2 microstrip arrays in order to support multi-channel signal receiving. The simulation results showed its good performance in automoti ve radar applications.Model of the antenna is built in the simulation software CST Microwave Studio. After adjustment and optimization of the model, the results reach the prosed technical indexes. Antenna processing and manufacturing is based on the simul ation, the measurement of antenna radiation pattern has been carried out later. The measurement results concide with the simulation, which proved the reliability of antenna design.Furthermore, in order to explain the radiation mechanism of antenna array, the analysis of antenna is proceeded in theoretical level. The performance of this antenna array is evaluated by numerical method combined with array element theory. The results of calculation raech an agreement of simulation and mesurememt, which explains the antenna’s low sidelobe level. The results prove that this antenna module is applicable in the automotive radar applications. |
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