“…Over the past few years, in order to improve the gain, directivity, and radiation efficiency, while overcoming the limitations of silicon substrates and maintaining reduced size, different types of metamaterials have been proposed, such as Artificial Magnetic Conductors, AMC; High Impedance Surfaces, HIS; Electromagnetic Band-Gap structures, EBG; Double Negative Materials, DNG; Zeroth Order Resonators, ZOR; and various types of metasurfaces 13 – 20 . In other works, external resonators 21 , or lenses are used 22 , 23 , micromachining is performed around and below the antenna 24 , the doping profile around the antenna is tailored 12 , its position is optimized 25 , reflectors are employed 26 , and high resistivity (HR) substrates are used 27 , 28 .…”