Accurate and robust characterization of metasurface-enabled frequency reconfigurable antennas by radially homogeneous model

A category of frequency reconfigurable antennas realized by rotating mechanically a metasurface mounted atop a source radiator has attracted growing attention. Their electromagnetic properties and range of frequency reconfigurability have, nevertheless, not been satisfactorily studied. To this end, an equivalent radially homogeneous model is firstly proposed in this paper. The retrieval process is accordingly formulated to address the polarization dependence of the retrieved effective electromagnetic parameters. A couple of typical metasurface-based frequency mechanically reconfigurable antennas are thus characterized by the proposed model. The predicted central operating frequencies are validated against the results of full-wave simulation and the measurement ones of manufactured proof-of-concept prototypes. Further comparisons to the isotropic and the anisotropic models confirm superior accuracy, robustness, and simplicity of the proposed characterization model. In addition, frequency reconfigurable range is shown to be determined by the anisotropy of the metasurface, related to the geometrical symmetry of its constitutive unit cell.