Compact Log-Periodic Single-Port Planar Antennas for D-Band Monolithic RIS Panels

IEEE Antennas and Wireless Propagation Letters. 2025. Vol. 24. No. 1. P. 88–92.

Shurakov A., Razakova A., Lvov A., Belikov I., Prikhodko A., Goltsman G.

The quality of wireless connections in the sixth-generation (6G) communication networks is tightly linked to the capabilities of smart antenna environments. They should enable effective routing of ultra-narrow radio beams, intrinsic to D-band channels, and make use of so-called reconfigurable intelligent surfaces (RISs). Practical RISs are seriously judged by their cost and operation efficiencies. In this letter, we report on the development of a robust single-port antenna that can be used as part of a D-band RIS panel. The antenna is presented by a grounded log-periodic spiral on thin quartz substrate. Two types of spirals are developed for either a static beamforming or dynamic beam steering in reflected light. The geometry- and load-controlled phase shifts consistently cover a 0 ∘ to 350 ∘ range upon reflection of 140 GHz waves with the angles of incidence within ± 75 ∘ . This is achieved by changing either first, the spiral scaling factor between 0.658 and 1 in half-wave cells or second the spiral load capacitance between 0 fF and 20 fF in quarter-wave cells. These values are feasible for gallium arsenide (GaAs)-on-quartz planar Schottky diodes. The simulation results are justified by prototyping. For a 1.3 k pixel proof-of-concept reflectarray with geometrically phase-configured cells, we measure the beamwidth, sidelobe, and cross-polarization levels of 4 ∘ , − 13 dB, and − 26 dB, respectively. All together suggests great potential of the developed antennas as basic elements for the physical layer devices of reflection-aided 6G wireless communications.

Keywords: reflection, geometry, capacitance, Spirals, antennas, reconfigurable intelligent surfaces, Schottky diodes, Beam steering, 6G mobile communication