Array-antenna patterns are calculated for arrays of radiators of time-limited signals. Antenna patterns are calculated in the time domain by superposition of temporal waveforms at various angles. Monocycle waveforms are used as canonical building blocks to illustrate the method. Pulses are short compared to the dimensions of the antenna and interference phenomena are localized to a percentage of the total aperture. Low sidelobes are achieved through two methods: (1) the limited interference phenomena afforded by monocycle excitation, and (2) randomization of individual element placement. Randomization of element placement serves to destroy periodicities in the physical aperture. In rectangular arrays where elements are arranged in rows, periodicities in the lattice along the principal planes make sidelobes higher along these planes than for off-axis directions. This behavior is evident in arrays using both short-pulse and sinusoidal excitation. Periodicities in the physical aperture of arrays of short- pulse radiators have also been associated with a narrow-banding effect manifesting itself as spikes in the spectral response at particular angles. Randomizing the positions of the individual radiators, each radiating a broad-band signal, helps keep the spectrum broad for all angles. Sidelobe levels have been demonstrated which are well below the 1/n limit associated with unipolar-impulsive signals where n is the number of radiating elements.