Implementation Of Beidou Navigation Anti-Jamming Antenna

The Beidou Navigation and Positioning System is a space-based navigation and positioning system independently controlled by our country,which is of great significance in homeland security and defense applications.When the Beidou terminal device is used in these important occasions,the electromagnetic environment that needs to be dealt with becomes more complicated.In addition to unintentional interference in the normal environment,it is necessary to focus on man-made malicious interference.The adaptive nulling antenna performs weighting processing on the signals from different elements in the array,so that the pattern of the antenna array generates a null point in the direction of the interference source,so as to reduce the effectiveness of the jammer.The NLMS algorithm is a widely used adaptive filtering algorithm.The difference from the steepest descent method is that the algorithm uses a fixed gradient in the recursive calculation process based on the Wiener filter structure,and the algorithm does not involve correlation functions.And matrix inversion requires a lot of resources,so it is very suitable for engineering implementation.It is also because of the simplicity of the NLMS algorithm that it often becomes a reference benchmark for measuring the pros and cons of other linear adaptive filtering methods.In actual engineering applications,there is a situation where the amplitude and phase of the channel are inconsistent,which will cause deviation and disturbance of the antenna array manifold,which will affect the performance of the entire system.This scheme uses the NLMS algorithm to correct the array channel error,the algorithm calculation is simple,convenient for real-time processing,and easy for engineering realization.In engineering practice,in view of the problem of large recesses in the gain of the B3 antenna array at low elevation angles,this topic proposes four optimization schemes for frustum heightening,unilateral inclined platform,surrounding edges and metal pillars.The four optimization schemes are simulated and compared.This subject has studied the engineering realization of the Beidou anti-jamming antenna from both the hardware and software aspects,as well as the verification and confirmation of the engineering prototype.The research results show that the space-time adaptive nulling technology based on the power inversion criterion and the NLMS iterative algorithm can adaptively form a null for the direction of interference in the state of motion,and effectively suppress the interference signal;optimize the B3 antenna array and adopt The single-sided oblique array element can significantly improve the gain notch in the low elevation angle state,which is beneficial to improve the receiving performance of the antenna.