Abstract: Based on the wave-guide theory, the formulas used to calculate radiation fields excited by the airborne trailing antenna are deduced. According to the formulas, altitude gains are obtained, and the altitude gain fluctuation with the height of observing points is analyzed. Then, for the radiation fields excited by the trailing antenna, its variation characteristics with the antenna height, tilt angel and receiving azimuth angel are discussed, which has great reference value for trailing antenna study and application.