| Recently,with the increase in the number of automobiles,advanced driver assistance systems have flourished.As a key component of these systems,the application of millimeter wave radar in vehicles has become increasingly widespread.Currently,automotive millimeter wave radar is mainly used to detect the surrounding environment and provide road and vehicle information to drivers.However,with the increasingly complex electromagnetic environment,the issue of traffic safety caused by electromagnetic interference during normal operation of millimeter-wave radar has become urgent.Additionally,most automotive millimeter wave radars currently use microstrip antenna arrays as their transmitting and receiving antennas,inevitably causing problems such as large size,narrow operating bandwidth,and high integration difficulty.Therefore,research on interference theory models and high-performance antenna design for automotive millimeter wave radar systems is of great significance.This paper proposes a theory model for artificial square wave interference and builds an analysis and simulation platform for artificial square wave interference based on the theory model.The simulation and experimental results of the impact of square wave interference signals on millimeter wave radar at different carrier frequencies,different lowfrequency square wave signal frequencies,and different low-frequency square wave signal duty cycles verify the effectiveness of the model.Firstly,based on the working principle of millimeter wave radar and the theory of signal transmission and complex baseband reception,combined with the frequency domain analysis method of periodic signals,a detailed derivation and analysis of the impact of artificial square wave interference signals are conducted to establish the theory model for artificial square wave interference,and a simulation platform for artificial square wave interference signals is built based on the theory model.This article designs multiple working scenarios,obtains simulation results of millimeter-wave radar under artificial square wave signal interference,and builds an experimental testing platform for verification.The simulation results are compared with the experimental results,and it is found that the millimeter wave radar noise obtained through Fourier transform on distance is consistent between the two,with a maximum error of no more than 3dB,thus verifying the effectiveness of the simulation platform’s impact analysis.This platform provides a fast and effective analysis of the impact of artificial electromagnetic interference signals on automotive millimeter wave radar,and provides beneficial reference for the practical application of automotive millimeter-wave radar systems.In this paper,a high-performance automotive millimeter-wave radar lens antenna is proposed.Firstly,a metamaterial transmission unit is designed,which can achieve a 360° phase deviation under the condition that the transmission coefficient of the unit is greater than 0.7 by adjusting the length of the metal structure’s distant branches.Based on the generalized Snell’s law and the phase compensation principle of the metamaterial,an 11 × 11 unit metamaterial structure is designed,and the focusing effect of the metamaterial on the incident electromagnetic wave is verified by the plane wave perpendicular to the metamaterial incident plane.By using a microstrip patch antenna as the feed source and loading the designed metamaterial array structure,a lens antenna suitable for automotive millimeter wave radar is created.The designed lens antenna is 17.6 × 17.6 × 10.752 mm3 in size,which has a working frequency band of 75.8GHz-82.7GHz,an antenna gain of 18.4dBi at 77GHz,and a gain greater than 18dBi within the working frequency range.The half-power beamwidths of the E-plane and H-plane are 15.5° and 15.1°,respectively,enabling target detection over a wide range of angles.The automotive millimeter wave antenna designed in this paper has the characteristics of wide bandwidth,miniaturization,and easy integration,making it easy to manufacture and effectively solving the problem of large antenna size and narrow bandwidth in current automotive millimeter-wave radar systems. |
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