Evaluation Method for the Intermodulation Interference in an Integrated Shipboard Communication System

When an antenna is shared by multiple onboard communication transmitters and receivers,severe interference of nonlinear intermodulation may occur,and the overall electromagnetic environment will be affected. Aiming at the problem,this paper focuses on the generation principle of the interference and develops a module to calculate the exact intermodulation effects. Also,the relation between the number of communication channels and intermodulation products is provided. To demonstrate the proposed model,an ultrashort wave antenna is examined for the frequency distribution of intermodulation and the worst case of interference,and a method is then given to evaluate the impact degree of the interference. Finally,several available solutions to reduce the intermodulation interference are proposed,including reducing the number of communication channels,restraining the higher-order non-linear effects using T/R separate antenna systems,and increasing the transmitting frequency correlation in the pilot frequency communication system.