Metamaterial characteristics of dielectric resonator arrays in rectangular waveguide and free space

The study demonstrates the metamaterial characteristics of the arrays containing dielectric resonators by evaluating the permittivity and permeability coefficients of the array structures in rectangular waveguide and free space. For this purpose, the array with two closely spaced dielectric resonators is setup and placed both in a rectangular waveguide and free space one by one. The scattering parameters in both structures are extracted with full-wave simulations (CST Microwave Studio) and supported with measurement results. Then, the effective relative permittivity and permeability values are obtained with the deembedding technique and retrieval method. According to the results, the structures show double negative (DNG) characteristics at some frequencies. Therefore, the array with dielectric resonators is shown to have metamaterial characteristics. Besides, the DNG frequencies of both (waveguide and free space) structures are found to be consistent to each other. This means that the metamaterial behaviour of the dielectric resonator array is highly insensitive to the wave excitation where TE10 and TEM modes are excited in rectangular waveguide and free space, respectively.