Spoof surface plasmons spawning pencil-beam antennas of subwavelength profile

Slot-array antennas based on metallic waveguides have been widely used to generate pencil-beams, attracting attention due to their design simplicity and compact size. However, current slot-array antennas possess wavelength-scale profiles, which do not align optimally with the low-profile requisites of contemporary integrated communication and radar systems. Here, we propose a low-profile slot-array antenna designed specifically for the pencil-beam generation. Constructed with the two-dimensional-array (2D-array) slots situated on a sub-wavelength domino plasmon waveguide, the pencil-beam is generated with a peak gain of up to 21.6 dBi. Moreover, the generated pencil-beam allows for a wide scanning range of over 73.6° by adjusting the operating frequency from 45 to 65 GHz. Our research shows great potential for enhancing millimeter-wave radar capabilities and advancing communication systems.