2 × 2 Lens Array Antenna Using Square-Bottom Concave-Convex Lens in 300-GHz Band

A $2\times2$ lens array provides a half reduction of antenna height compared to the twice-diameter single-feed lens antenna with an almost similar gain performance due to the same aperture size. However, it generally suffers from a non-uniform amplitude distribution of each lens, which degrades the overall lens antenna performance. This study proposes a $2\times2$ lens array antenna composed of square-bottom lenses with a concave-convex lens shaping design to improve the uniformity and aperture efficiency. The measured results of the proposed $2\times2$ square-bottom concave-convex lens array antenna with a lens height of 9.74 mm achieved a boresight gain of 34.9 dBi, and the lowest sidelobe level observed was greater than −12 dB in the 300-GHz band.