Transients in cylindrical antennae

The transient response of the radiation field of a driven cylindrical antenna is investigated for the particular case of a step-function excitation. The theoretical analysis makes use of Fourier´s theorem to express the response as an integral over the response to all individual frequency components. The response as a function of time shows damped oscillations with a frequency determined by the first resonance frequency of the antenna. The response of the same antenna used as a receiver in a transient plane wave field is shown to be related to the radiation response by a simple integration process. By proper loading of the dipole, transient times of the order of the time needed for wave to travel along the dipole axis can be obtained. An experimental investigation is described in which the reception of a transient field due to a shock-excited distant transmitter is observed.