Electromagnetic metasurface lenses with the characteristic of being conformal to a cylindrical geometry are presented in this\nstudy. Based on the formulated principle of the cylindrical metasurface lens operating with transmission or reflection mode, the\ntransmission or reflection phase gradient varying along the circumferential direction of a cylinder is implemented. A focused\nbeam is observed at the objective focal point for each lens illuminated by a plane electromagnetic wave with transverse magnetic or\ntransverse electric polarization. A coaxial-fed microstrip patch antenna element is used as a feeding of cylindrical metasurface\nlenses and positioned at their focal points, so as to evaluate their application in the enhancement of antenna gain along the\nboresight direction. By virtue of the focusing ability of presented lenses, effectively enhanced boresight gain from the cylindrical\nmetasurface lens antennas are obtained, in comparison with the freestanding feeding antenna. The agreement between simulation\nand measurement validates the designs. Conformal integration or embedment of the electromagnetic lens into a certain platform\nskin with cylindrical characteristics is therefore potentially demonstrated, which implies an enhancement of boresight gain\nwithout obviously disturbing the local shape of the skin by apparent weight or drag.
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