Radiation Characteristics of Traveling-Wave Antennas Excited by Nonsinusoidal Currents

In this paper, the idea about traveling-wave antennas excited by nonsinusoidal currents for high-resolution exploration is advanced. First the analytic expressions of the radiation waveforms in the far zone produced by a single transient of current traveling along a straight wire are derived in time domain. Then the radiation characteristics of traveling-wave antennas excited by nonsinusoidal current, such as the mean-power pattern functions and the directivity, are given, and the space waveform control and radiation efficiency are discussed. Based on previous results, the radiation waveforms of dipole antennas excited by pulse current are obtained from time- domain analysis. In a practical example, comparing these waveforms with corresponding waveforms obtained from frequency-domain analysis and measured data in [4] and [13], good agreements are obtained in various radiation directions. Some errors in [14] are also pointed out and corrected.