Beamforming in time-domain arrays

The Air Force Research Laboratory has developed a number of impulse radiating antennas (IRAs) for use in various ultra-wideband (UWB) and UWB high-power microwave (HPM) applications. Many of these antennas are designed to behave as differentiating antennas excited by a fast-rising step waveform, thereby resulting in a large-amplitude, narrow pulse in the far-field. In order to mitigate some of the limitations of reflector IRAs and lens IRAs, a new class of IRAs-the array IRA-has been proposed and examined in a number of studies. The principle benefit that is realizable with an array IRA is the potential for electronic beamsteering. Secondly, array IRAs will allow for far-field power combination from solid-state sources that are currently under development. In addition to these primary benefits, array IRAs provide a reduction in volume and the related mass of the antennas. It is important to note, however, that these benefits come at the cost of the added complexity associated with the precise timing of the array elements that is necessary for beamforming and far-field power combination.