System level link budget method

A simple mathematics iteration method was used to calculation of communication link margin between the ground station and aircraft in the past. However, factors such as complex vehicle model and climate conditions can cause radiation pattern distortion in the actual application. A method to assess the system level link budget was constructed. The relative changes equation of antenna radiation pattern caused by attitude change was established by applying rotation transformation matrix. Radiation pattern distortion information of installed antenna was simulated. Radiation pattern was used to data mining according to the relative changes variation. The link margin was computed under variable attitude by applying entire system link margin expression. Finally, examples about communication link performance between the ground navigation station and aircraft ultra-shortwave antenna, and between the ground heading station and aircraft heading antenna were used to validation the practicality of this method.