Decoupling Evaluation of Compact Phased Array Radars

In this paper, we investigate the effects of mutual coupling in phased array radars, and compare two techniques that ensure mitigation of the degrading effects that arise when the active elements are placed close together in the array. In this work, we aim compact arrays with inter-element spacing of less than half of the free-space wavelength. Since the phased array operates both in the transmitting, as well as in the receiving mode, it becomes necessary to analyze how the electromagnetic coupling affects the radiation pattern of the antenna elements for different scanning angles. The mismatch at each antenna port, as well as the distortion of the array radiation pattern will vary depending on how we feed the elements in the array. To overcome the effects of mutual coupling, we compare two techniques for decoupling: the use of metallic walls, and the use of decoupling and matching networks comprised of microstrip lines.