For high frequency electromagnetic wave(2~30MHZ)

it is very difficult to calculate radiant and transmittal characteristics of antenna located in complex environment.With the development of high frequency technology

the problems need to be solved imminently.In this paper

finite difference time domain method is used to calculate this problem.First the radiant characteristics of the monopole located on lossy ground are calculated.Then the characteristics of the electromagnetic wave transmitted by antenna located near coast passing a section of lossy ground are analyzed

and the characteristics of far electromagnetic strength related to the length of lossy ground are given.The surface impedance is used in this paper

that reduces calculation amount and memory space to a very marked degree.