Abstract
This paper proposes an ultra-compact Near-field Focusing (NFF) setup at 60 GHz. The proposed configuration is included a planar substrate integrated waveguide (SIW) slot array as a feeder for a three-layer transmissive coded metasurface lens. A comprehensive design methodology is presented, encompassing unit cell design, coded metasurface lens synthesis, and planar slot array design. The transmissive metasurface lens performance is studied and validated by numerical and analytical approaches. Then, the planar slot array design considerations are elaborated, investigating the amplitude and phase of the resulting waves to ensure that quasi-plane waves are produced in the near-field region. Finally, the slot array is employed to illuminate the designed metasurface where the distance between the feeder and metasurface lens is 2 mm (0.4λ), which shows the integrability and being packed of the proposed setup, contrary to the conventional metasurface-based NFF structures. There are fair agreements between analytical, numerical, and measurement methods to verify the presented approach. It turns out that the proposed device can focus waves close to the diffraction limit, which results in a high-resolution efficiency.