Study On Adaptive Interference Suppression Method In The High Frequency Band

The sky-wave Over-the-Horizon Radar (OTHR) operates in the high frequency band. Suppressing the external strong interference is crucial to enhance the performance of OTHR. The HF interference suppression methods are discussed in this dissertation.Firstly,a conventional digital beam-forming method is simply narrated in this dissertation.Since the weights of conventional digital beam-forming are unchangeable, the HF interference can not be effectively suppressed,whereupon,adaptive digital beam-forming method is introduced. However, the HF interference is not always a narrow band signal.sometimes its is very wide.Therefore,the conventional adaptive digital beam-forming method can not mitigate the HF interference effectively. In order to solve this problem, we general use a time-delay tap on every antenna element .Although, adaptive digital beam-forming method can perform nearly perfect performance to the sidelobe interference ,its can not do well to cancel the mainlobe HF interference,and bring some negative impact.A method base on block matrix and the other method base on correlation function of Cochannel Interference to cancel HF interference are given and been make a contrast.We can get a good performance ,when the mainlobe interference is a narrow band HF interference.At the end of this dissertation,a new stap method which combined with method in spatial and time above, is introduced.