Frequency agility of dielectric resonator using top-loaded rotatable anisotropic metasurface

Dielectric resonators (DRs) are widely investigated and applied due to the high Q-factor feature. Their frequency agility is desperately needed in modern communication systems. In this letter, we propose a novel tuning method for DRs using top-loaded rotatable anisotropic metasurface, instead of the traditional mechanical tuning structures or electrical switches. The effective permittivity of the anisotropic metasurface varies with the E-field direction of the incident wave. We can tune the resonate frequency by rotating the metasurface placed on the top of the DR. To demonstrate the feasibility of this method, a tunable DR with the anisotropic metasurface printed on a thin substrate is designed, fabricated, and measured. With a compact profile, the prototype provides a wide tuning range of 8.4% from 4.80 to 5.22 GHz and a Q-factor higher than 1098. The good tuning performance makes the proposed method highly potential for tunable filters and frequency-reconfigurable antennas.