Basic study on novel base-station filter using artificial dielectrics

An artificial dielectric is a material made artificially in which arranged metal strips work as molecules in a crystal. The artificial dielectric has characteristics which are not in natural dielectric, such as an extraordinary high dielectric constant and anisotropy. High dielectric constant is effective in filter miniaturization, and anisotropy contributes to spurious suppression. To improve the performance of filter using TE_01δ-mode with direct-connected I/O coupling, I/O coupling structure was investigated. It was possible to control k_e and spurious independently by optimizing cell structure of I/O port. The experimental filter was designed and fabricated based on the results. The filter showed excellent performance with desired bandwidth and spurious performance.