Transient fields of small loop antennas

A rather simple and general analysis allows us to calculate directly the transient response of many different radiators of practical interest in the time domain without the knowledge of the corresponding time harmonic solution. For example, we present exact expressions for the transient near- and far-field around small circular current loops involving arbitrarily time-varying excitation. The resulting convolution integrals have been numerically evaluated for step function currents with finite rise time, thus showing the influence of finite loop radius on the radiation field in comparison with the ideal magnetic dipole.