Compact Matryoshka DGS Using Dielectric Resonator

In this paper, a compact matryoshka DGS using dielectric resonator (DR) is proposed. Despite the use of dielectric resonators to obtain band-stop frequency response not being a new idea, the proposed compact matryoshka DGS is an original contribution, since only recently the matryoshka geometry was used in DGS applications. Furthermore, a numerical analysis of the positioning of the DR is presented, which makes it possible to determine the region of the DGS for which the minimum resonant frequency is reached, and the resonant frequency range that can be obtained. To the best of the authors' knowledge, this numerical analysis is an unpublished result, even more so, for the matryoshka DGS. The matryoshka geometry was described, including initial design equations. To verify the expected characteristics (miniaturization, selectivity, and resonant frequency tunability), two compact matryoshka DGSs (DGS1 and DGS2) were designed using a high permittivity ceramic (MCT-115) as DR. The obtained numerical and experimental results showed good agreement, and the initial design equations proved to be applicable, which allows new dimensions to be determined for other resonant frequencies, according to the application requirements. Resonant frequencies ranging from the maximum value to 33% (DGS1) and 27% (DGS2) were achieved, depending on the DR position. Considering lambda(0) the wavelength in free space, corresponding to the resonant frequency, DGS1 and DGS2 achieved an occupied area of 0.04 lambda(0 )x0.004 lambda(0), and 0.05 lambda(0)x0.05 lambda(0) , respectively, a good miniaturization. The proposed compact matryoshka DGS may be especially attractive for applications that require a very selective band-stop frequency response. If a wider band-stop is required, the proposed DGS can be cascaded.