Substrate-Integrated Defected Ground Structure for Single- and Dual-Band Bandpass Filters With Wide Stopband and Low Radiation Loss

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 singleband 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 dualband 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.

Compact 1.75–2.7 GHz Tunable BPF With Wide Stopband Up to 9.5 GHz Using Harmonic-Controlled SIDGS Resonators

“…Port 2 electronically tuning elements. Recently, substrate-integrated defected ground structure (SIDGS) [17]- [18] is proposed for various kinds of high-performance passive components with wide stopband, low radiation loss, and compact size. However, such filters with fixed operating frequency can hardly satisfy the requirement of multi-standard communication circuits and systems.…”

Compact Filtering Balun With Wide Stopband and Low Radiation Loss Using Hybrid Microstrip and Substrate-Integrated Defected Ground Structure

“…Such radiation could cause an extra insertion loss and EM interference to adjacent devices. SIDGS is proposed to confine most of the divergent EM-field, which effectively reduces the radiation loss compared to the conventional DGS [15]- [16]. In this balun design, the microstrip is integrated with the SIDGS by the surrounding ground and metal-vias.…”

“…However, these baluns could easily generate high radiation at stopband. Recently, substrate-integrated defected ground structure (SIDGS) [15]- [16] is developed with wide stopband and wideband low radiation loss. Nevertheless, the design of filtering balun with the good in-band performance, wide stopband, and wideband low radiation loss and compact size for flexible integration remains a great challenge.…”

Compact UWB BPF With Broad Stopband Based on Loaded-Stub and C-Shape SIDGS Resonators

“…Nevertheless, high radiation loss allocated by the DGS makes filters not easy to integrate in passive circuit. Recently, substrate-integrated defected ground structure (SIDGS) filters [36]- [37] are developed with low insertion loss, wide stopband, and wideband low radiation loss, simultaneously. Nevertheless, the design of compact UWB BPF with enhanced passband and stopband performance for flexible integration remains challenges.…”