Miniaturized Hexagonal Stepped-Impedance Resonators and Their Applications to Filters

Miniaturized hexagonal stepped-impedance resonators and their applications to bandpass filters are presented. Based on the odd- and even-mode equivalent circuits, the resonance characteristics of these resonators are investigated. A series of circuit configurations, including the third-order Chebyshev, trisection, and fifth-order cascaded trisection filters, are constructed by the proposed resonators. These filters are very compact and have good stopband responses. Measured results validate the analysis and theoretical prediction with good agreement.