Exact and approximate methods for calculating log-periodic vibrator antennas

Two methods for calculating the characteristics of log-periodic vibrator antennas are discussed and compared: (1) a rigorous integral equation method with a system of piecewise-sinusoidal functions as the basis and (2) the induced-emf method. It is found that, for log-periodic antennas with a frequency band greater than one octave, the induced-emf method is applicable only when vibrators of the active region play a dominating role in the antenna radiation.