Abstract
In this article, two types of substrate-integrated defected ground structure (SIDGS) resonant cells with wide upper stopband and low radiation loss are presented for filter implementation. Such SIDGS resonant cells are composed of two dissimilar DGSs surrounded by the bottom ground and metal-vias, which cannot only introduce wide stopband with low radiation loss but also be flexible for integration. Based on the aforementioned SIDGS resonant cells, single- and dual-band bandpass filters (BPFs) are designed and fabricated. The single-band BPF centered at 2.40 GHz exhibits an ultrawide upper stopband up to 19.7 GHz with a rejection level of 31 dB, whereas the measured stopband total loss (i.e., including radiation, metal, and substrate loss) remains about 30% up to 19.3 GHz. The dual-band BPF operated at 2.10 and 3.78 GHz exhibits an ultrawide upper stopband up to 17.8 GHz with a rejection level of 23 dB, whereas the measured stopband total loss is less than 16% up to 11.4 GHz.
Highlights
W ITH the increasing development of modern wireless systems, electromagnetic interference (EMI) and interference suppression become major challenges for circuit designs [1]
Based on the basic concept of substrate-integrated defected ground structure (SIDGS) mentioned earlier, two types of SIDGS resonant cells are proposed, as shown in Fig. 2, which are employed for singleand dual-band filter implementations with specific coupling schemes
Both SIDGS resonant cells are composed of two stepped-impedance defected ground structure (DGS), which are surrounded by the bottom ground and metal-vias
Summary
W ITH the increasing development of modern wireless systems, electromagnetic interference (EMI) and interference suppression become major challenges for circuit designs [1]. To extend the stopband bandwidth, the wiggly line [10], compact microstrip resonant cell resonator [11], parallel-coupled line [12], and periodically nonuniform coupled microstrip line [13] are proposed for single-band design, while the CPW-to-microstrip [14] and net-type resonators [15] are proposed for dual-band design These structures either suffer from a high insertion loss or a low stopband rejection level. Following the previous SIDGS BPF design, this article expands the detailed theoretical analysis of SIDGS cells for filter design, including resonance, spurious suppression, and radiation suppression.
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