Electrically controlled flat-top pattern synthesis of the high-power pulsed ultrawideband array excited by transistorized pulsers

In this paper, a kind of electrically controlled time-domain flat-top pattern synthesis technique is proposed and studied for high-power ultrawideband arrays excited by transistorized pulsers. First, to determine the relative excitation time delays of the array elements, an optimization model is proposed that considers both the effective potential gain and the main lobe shape of the peak-power pattern. The upper bound of the time delays is constrained by the pulse width of the radiating signal, the array dimensions, and the expected flat-top width; to ensure the uniformity of the shaped pattern, the ripple within the coverage range is taken as a constraint. Then, based on the genetic algorithm, the shaping characteristics of the array are studied. It indicates that the flat-top width and the ripple of the shaped pattern are conflicting factors; a shorter time step of the time-delay module could lead to a minor ripple. Subsequently, an electrically controlled four-unit time-delay module is designed and developed based on PIN single-pole double-throw switches and coplanar waveguide delay lines. It can generate a time delay ranging from 0 to 1070 ps, with an average time step of 107 ps. The proposed module can transmit high dV/dt triggering signals, which is crucial for improving the synthesis efficiency by decreasing the pulse jitter. Based on the sample array, an effective potential synthesis efficiency of 97% is achieved, and a 20° flat-top pattern is designed and realized. The proposed technique could also be used for arbitrary pattern synthesis.