Calculation of Yagi antenna responses to an electromagnetic pulse

The purpose of this paper is to compute the response of a 100 MHz Yagi antenna to an electromagnetic pulse (rise time 10 ns, pulse width 200 ns). Two different techniques are investigated. With the first one, integral equations are solved in the frequency domain and then a Fourier transform is performed. With the second one, Maxwell's equations are solved everywhere within the space around the antenna, using a finite difference method in the time domain. To solve the very problem dealt with, the time domain method turns out to be the more efficient. The overall antenna response can be divided into a short time waveform followed by a long time one. The long time response exhibits the same directivity effect as the one expected from the antenna when operated at its nominal frequency. The short time response depends also on the azimuth but in a rather different way. That last point can be accounted for when combining the differential and common modes of the driven folded dipole.