Ultrasparse, ultrawideband phased arrays

Current technology in ultrasound and electromagnetics is now able to construct radiating array elements that can transmit a high energy pulse which has only two or three cycles. The corresponding arrays are called ultrawideband (UWB) arrays. In a highly thinned UWB array, the distribution of side energy is very different from conventional narrowband (NB) arrays. Due to the UWB nature of the pulse, the radiated waveform from these arrays varies in time. As a result, the waveform has an extra dimension with respect to NB across which undesired side energy can be distributed. UWB arrays can be highly thinned and achieve a much lower side energy level than NB arrays. This paper presents a method for characterizing ultrasparse ultrawideband one- and two-dimensional arrays. Contrary to conventional wisdom, this analysis shows that in a highly thinned UWB array, a periodic array is preferred over a random array.