Tunable Dielectric Resonator-Based Left-Handed Leaky Wave Antenna

Recently, left-handed (LH) metamaterials have been achieved by arranging an array of TE resonant dielectric resonators (DRs) in a cut-off parallel plate waveguide [1], [2]. Since negative permittivity is provided by the TE cut-off background, the DRs only need to generate the required negative permeability in order to realize a LH metamaterial. This configuration provides a more flexible choice in structural parameters and uses a non-metallic resonant structure for achieving negative permeability that can be scaled to terahertz frequencies and beyond. One of the unique features of a LH metamaterial-based leaky wave antenna is that it can scan from back-fire to end-fire simply by changing the operational frequency. To overcome this frequency-dependent feature, an electrically-controlled tunable leaky wave antenna has been proposed [3]; the dispersion curve can be shifted by varying the bias voltage of the varactor diodes in each unit-cell. In contrast to the frequency and electrically controlled leaky wave antenna, this paper presents a mechanically controlled leaky wave antenna suitable for DR-based LH transmission lines. The dispersion curve is shifted when the boundary condition on the other side of the radiation aperture changes. A 15-cell leaky wave antenna is designed with the proposed structure and the radiation patterns are measured to confirm the capability of mechanical tunability for the maximum beam direction.