A low-profile ultra-wideband aperture stacked patch antenna is investigated as a radiator of ultra-wideband radio pulses with 50% relative bandwidth. Antenna design is based on low permittivity materials such as Rogers RO 4003, teflon and foam. On the basis of proposed stacked patch a 4-element linear antenna array was designed and investigated. Frequency-domain results demonstrated very good array elements matching and negligible mutual coupling. Simulated radiated transient pulses are presented for different observation angles, energy patterns and fidelity factors are calculated. Time-domain results evidence small radiated pulse degradation and high fidelity factor values for broadside directions. Index Terms-aperture stacked patch antenna, ultra-wideband antenna, linear antenna array, time-domain electromagnetics.