Low-Cost Quasi-Planar Dielectric Patch Resonator Filters Shielded by AMC Surface

The traditional dielectric resonator filter (DRF) is costly due to the high profile, machining and positioning of individual dielectric blocks and supports, and the necessity of metallic enclosure. To tackle this problem, this article presents a novel dielectric patch resonator (DPR) filter shielded by the artificial magnetic conductor (AMC). The proposed resonator is realized by sandwiching a thin DPR between a bottom-grounded substrate and an AMC plate, where the AMC is realized by a mushroom-type electromagnetic bandgap (EBG) surface printed on a substrate. It is quasi-planar and therefore suitable for integration in multilayer circuits. Three resonator schemes utilizing different fundamental modes (TM01, TM11, and TE11) are presented. The resonant frequency, spurious free window, and quality factor of each scheme are investigated by parametric analysis. The merit of high-quality factor (around 900 to near 2500 at 19 GHz) can be found from the simulated results. Compared to the traditional dielectric resonator (DR), the proposed one features a lower cost as it allows multicoupled DPR to be manufactured as a monoblock and various coupling configurations (positive, negative, or mixed) to be printed on the shielding substrate. For demonstration, four bandpass filters (BPFs) are designed, fabricated, and measured. Good agreement can be observed between the simulated and measured results.