Abstract: The mathematical model of electromagnetic compatibility and the distribution of air-craft antenna system are investigated.The solutions of the antenna gain and electromagnetic in-terference margin in the regions of low frequency,resonance and high frequency are discussed.By using the basic analytical method of the EMI margin the distributed antenna system can be deter-mined.The main program flow chart of distributed antenna design is given,and illustrated with examples of the microstrip antennas.

Key words: electromagnetic compatibility, aircraft antennasm}crostnp antennas