A Focused Metasurface Lens Antenna with Gain Enhancement

A specialized metasurface has been developed for lens antenna applications. This innovative metasurface unit cell comprises five metallic layers and four dielectric layers. Each metallic layer consists of a pair of back-to-back split resonant rings. The proposed unit cell is highly effective with a transmission phase coverage exceeding 360∘ and a transmission amplitude larger than 70% at X-band (8.8-11.2 GHz). The unit cell has been thoroughly designed, fabricated and tested. To verify the present unit cell, a metasurface array with 27×27 elements is designed. An X-band horn antenna is used as the feed source. Simulation and measurement results show that the electromagnetic wave from the feed horn is focused within the operating band, resulting in a measured gain of 16.9 dB at 9 GHz and 19.2 dB at 11 GHz. Thus, a gain enhancement of 5.4 dB at 9 GHz and 5.7 dB at 11 GHz are obtained, making it a good reference for engineering applications.