“…Consequently, mm-Wave antenna systems are required to provide high gain and high efficiency [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Various approaches and implementations of radiating elements have been proposed for the mm-wave frequency bands, including flexible antennas [ 6 , 7 ], 3D printed antennas [ 1 , 11 ], microstrip patches and slots [ 2 , 4 , 8 , 9 , 10 ] and conventional DRAs on printed circuit board (PCB) technology [ 3 , 5 , 9 ]. Printed antennas, i.e., patches and slots, are intrinsically narrowband and suffer from conductor losses as well as the likely excitation of surface waves, both of which lead to lower efficiency.…”