Antennas for nonsinusoidal waves. III - Arrays

The variation in time of the electric and magnetic field strengths of a nonsinusoidal wave radiated by an array of radiators is a function of the azimuth and the elevation angle. For simple time variations, such as that of a rectangular pulse in the direction of the array axis, this time variation can be determined analytically as a function of the angle. Peak-amplitude, peak-power, and energy patterns, which are the equivalent of amplitude and power patterns of sinusoidal waves, can then be determined. In addition, a rise time or slope pattern can be obtained that yields a much better angular resolution for large signal-to-noise ratios. No equivalent exists for sinusoidal waves owing to their lack of bandwidth. It is noted that the principle of the monopulse antenna array can also be carried over from sinusoidal to nonsinusoidal waves. A monopulse amplitude pattern is obtained which changes rapidly from positive to negative values in the vicinity of the angle of incidence beta = 0. The resulting improvement in the accuracy of angle measurement is fully analogous to sinusoidal waves. In addition to the monopulse-antenna pattern, a monopulse antenna slope pattern can be obtained that promises a much better accuracy of angle measurement.