A high-power source of ultrawideband radiation based on the synthesis of electromagnetic pulses with different frequency bands has been created. A four-channel former of highly stable bipolar pulses with durations of 0.5 and 1 ns was developed. Each element of a 2 × 2 array of combined antennas was excited from its former channel. Two modes of radiation synthesis were studied: according to the maximum field strength and the maximum spectrum width. For the first mode, radiation pulses with a frequency band of 0.39–2.13 GHz and an effective potential of 600 kV were obtained. Synthesized radiation pulses with an extended frequency band of 0.15–2.7 GHz and an effective potential of 200 kV were obtained in the second mode. The pulse repetition frequency was 100 Hz