Ultra-Compact 60-GHz Near-Field Focusing Configuration Using SIW Slot Array Loaded by Transmission Coding Metasurface Lens

This communication 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 meta surface lens. A comprehensive design methodology is presented, encompassing unit cell design, coded meta surface lens synthesis, and planar slot array design. The transmissive meta surface 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 meta surface where the distance between the feeder and meta surface lens is 2 mm (0.4 lambda), which shows the integrability and being packed of the proposed setup, contrary to the conventional meta surface-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-resolutionefficiency.