Low-pass filters based on crystal-like inhomogeneities

The paper proposes microstrip low-pass filters (LPF) based on three-dimensional electromagnetocrystalline inhomogeneities (ECI). The calculated responses (AFRs) of quasi-lumped reactive elements based on traditional and ECI structures are compared. AFRs of quasi-lumped ECI-based reactive elements are noticeably close to AFRs of lumped elements. The frequency of the AFR first minimum of ECI-based LPF is three times as large as the similar frequency of LPF based on traditional structures. Combined ECI incorporating the inductive and capacitive elements are also proposed. LPF structures based on single and combined ECI are presented. The calculated and experimental parameters and AFRs of filters are presented that illustrate a significant size reduction and performance improvement in the suppression band as compared to the filter having the traditional structure. The amplitude-frequency characteristics have been calculated using the three-dimensional simulation in the environment of CST Microwave Studio software package