A phase-comparison monopulse system based on a 4D antenna array

Conventional monopulse systems based on sum and difference patterns produced by traditional arrays face the contradiction of angle-resolution and angle-searching range, and a compromise between them usually has to be made. In four-dimensional (4D) antenna arrays, multiple pairs of sum and difference patterns can be produced simultaneously at the center frequency and low sidebands. By designing the time sequences reasonably, the multiple sum and difference patterns point in different directions, covering a much wider angle-range. In this paper, the conventional phase-comparison monopulse is introduced into a 4D array to form a novel monopulse system by which both high angle-resolution and wide angel-searching range are realized. Theoretical analysis shows that the novel monopulse system covers a ±60^o angle-searching range without beam-scanning. An experiment system based on an 8-element 4D array is established, and measurement results validate the effectiveness of the proposed system.