Aiming at the problem that radar is easy to be damaged when being attacked by HPM weapons， this paper theoretically analyzes the relationship between the farthest protection boundary to antenna gain and receiving front-end limiter’s capability， and compares the capability of reflector radar and active phased array radar against front door coupling attack from the perspective of spatial filtering. The analysis shows that only when the HPM weapon is near the main lobe range of the reflector radar antenna， its front door coupling attack effect is stronger than that of the active phased array radar； on the contrary， it is weaker than active phased array radar. Because the main beam of the reflector antenna radar is very narrow， the attack time window is very short， so the reflector antenna radar has stronger protection ability when facing HPM weapons.

The analysis of radar fault cause text is helpful to locate the fault location， facilitate equipment maintenance and analyze equipment performance. Knowledge extraction， representation and management of radar fault cause text using knowledge graph technology can effectively improve the utilization efficiency of the text， quickly locate the fault location and analyze the equipment performance in time. On the basis of summarizing the characteristics of radar equipment fault cause text， radar equipment fault cause knowledge graph is constructed by a method combines both the scheme layer and the data layer. The scheme layer of the knowledge graph in the top-down style is designed， which defines the knowledge framework， the concept types， and the relationships between the concepts of the knowledge graph. For the text characteristics， the data layer of knowledge map is constructed in the bottom-up style： in order to solve the problems of small sample size and compound words entity recognition， entity naming recognition is carried out by Att-AlBERT-BiGRU-CRF model. The ALBERT-BiGRU-Att model is used for relationship extraction. Experiments show the effectiveness of the above extraction method. Based on the entities and relationship， the knowledge graph of radar fault causes is constructed.