Variable Multi-Band Metasurface Reflector with Controllable Direction Using Varactor Diodes Mounted Large-Via Mushroom-Type Structure

Reconfigurable metasurface reflectors, which are key components of the intelligent reflecting surface (IRS) have recently been considered as the countermeasures for the coverage hole problem in the fifth- and sixth-generation (5G/6G) mobile communication systems. In this paper, a novel varactor diodes mounted large-via mushroom-type (VDLM) structure with a wide reflection phase range is proposed to realize the variable multi-band metasurface reflector with controllable direction. Specifically, two varactor diodes for controlling the reflection direction and frequency band are mounted on the unit cell of the metasurface. In addition, the proposed VDLM structure consists of a large grounding conductor cylinder (large-via) to expand the reflection phase range, and mitigate the influence of the design gap that is caused between each frequency. According to our electromagnetic simulation results, the reflector with the proposed VDLM structure could control the reflection direction at selected frequency with a low sidelobe suppression ratio.