Efficiency optimization of millimeter wave FR4-based metasurface using lossy spatial filter modeling

This paper presents millimeter wave beam steerable lens antenna where the lens consists of numerous unit cells made of low-cost but lossy substrate, FR4. It is found that through lossy spatial filter modeling the unit cells employing low-pass filter responses are more influenced by loss factor compared to the unit cells employing band-pass filter response. Therefore, the proposed lens is designed to achieve low insertion loss with wide tunable range of phase shift by identifying and selecting unit cell topology providing relatively low insertion loss to achieve target phase shift. It is demonstrated that this practical consideration based on analysis of lossy factors in equivalent circuit can achieve higher than 1.5 dB efficiency enhancement.