An electronically scanned array (ESA) is configured for a high-degree of isolation between adjacent radiating elements and between co-located ports. Radiating elements of the ESA include a centrally located slot-aperture configured as a radiating source, and multiple via-apertures positioned around and between each port of the co-located ports. An amount of metamaterial structures found in a unit cell of an antenna layer ascendingly increases from a bottom antenna layer to a top antenna layer, with groups of metamaterial structures differing in orientation with respect to unit cells of two or more antenna layers and with respect to two groups found within a unit cell of the top antenna layer.