Compact Dual-Mode Open Loop Microstrip Resonators and Filters

A novel compact microstrip dual-mode resonator and filter are proposed. The characteristics of the dual mode resonator are investigated. It is found that the filter response exhibits a desirable stopband response where the first spurious passband naturally occurs at 3f
₀
. Finally, methods of miniaturizing such resonators and filters are discussed. The proposed structure was able to achieve 60% size reduction.