Analysis of Scan Blindness in Connected Slot Arrays

Connected slot arrays attract substantial interest for their wideband and wide scanning performance. Nevertheless, similarly to other periodic structures, they may suffer from scan blindness under specific conditions limiting their operation. In this communication, we provide insights into the generation of scan blindness for connected slot arrays. The circuital representation of the unit cell of the array in an infinite periodic environment and with an arbitrary wide angle impedance matching (WAIM) layer is used in a transverse resonance method approach to derive the free resonances of the structure. A clear connection is identified between the free resonances of the array and the scan blindness. More specifically, we show that blindness occurs in the vicinity of leaky-wave poles. This straightforward analysis allows us to efficiently detect possible points of total reflection while providing a deeper understanding of the operational principle of connected slot arrays.