en 5-Microwave Passive Circuits Microwave Passive Circuits Research Paper Research Paper <span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif">Bandpass filters (BPFs) are critical components in 5G radio-frequency front-end systems, where wide bandwidth, low insertion loss, and compact size are simultaneously required. In this paper, a metamaterial-inspired wideband BPF based on Complementary Split Ring Resonators (CSRRs) loaded with a dumbbell-shaped Defected Ground Structure (DGS) is proposed for mid-band 5G applications centered at 4.7 GHz. Unlike conventional designs that rely on commercial electromagnetic solvers, the proposed filter is developed and analyzed using a fully open-source electromagnetic simulation framework based on Open EMS, enabling cost-effectiveness and design reproducibility. The design evolution from a single-ring CSRR to a triple-ring configuration is systematically presented to enhance magnetic coupling and bandwidth. The incorporation of a dumbbell-shaped DGS further modifies the ground current distribution, leading to improved selectivity and reduced insertion loss. The optimized filter achieves a fractional bandwidth of approximately 43%, a minimum insertion loss of 0.72 dB, and a return loss better than -35 dB using a low-cost FR-4 substrate. Comprehensive parametric analysis, metamaterial characterization, group delay response, and electromagnetic field distribution are provided to validate the proposed approach. The results demonstrate that the open-source Open EMS-based methodology can achieve performance comparable to commercial solvers, offering an accessible and reliable design pathway for next-generation microwave filter development.</span></span> Bandpass Filter, Complementary Split Ring Resonator, Defected Ground Structure, Scattering Parameters, Open EMS.s, Open EMS 4257 4257 http://ijeee.iust.ac.ir/browse.php?a_code=A-10-6273-3&slc_lang=en&sid=1 Gauravkumar Asari grasari@vgecg.ac.in 1800319475328460017635 1800319475328460017635 Yes Department of Electronics and Communication Engineering, Vishwakarma Government Engineering College, Chandkheda-382424, Ahmedabad, Gujarat, India