In this paper, a time domain analysis for ultra-wideband short pulse radiation from wire monopole antennas and their arrays is presented. The pulse travels along the monopole antenna and reflects from the open end; during the pulse reflection, the pulse gets compressed. The analysis presented in this paper accounts for the pulse compression and the radiated pulse is compared with the measured pulse. Measured energy patterns for different pulse excitations of the monopole and monopole arrays are presented and compared with theoretical patterns.