An antenna assembly includes a metasurface antenna unit including a radiating structure, a feeding structure, and a grounding structure therebetween. The radiating structure includes radiating elements arranged in an m×n grid of m rows of radiating elements and n columns of radiating elements, where n is greater than m. The radiating elements are separated by radiating slots with edges of the radiating elements facing each other across the radiating slots. The grounding structure includes a ground plane having a coupling aperture therethrough. The feeding structure includes a single strip feedline for feeding the radiating elements. The strip feedline passes across the coupling aperture and feeds the radiating structure through the coupling aperture. At least one of the radiating elements is fed through at least one other radiating element across the corresponding radiating slot.