This paper introduces a novel wideband bandstop filter designed for S and C band applications, utilizing rounded interdigital meander lines and impedance stubs to achieve significant bandwidth and performance improvements. The proposed filter, with compact dimensions of 25 mm x 30 mm, exhibits a wide stopband spanning 4.58 GHz, covering critical frequencies for modern communication systems. The design leverages simple yet effective structural elements, including meandering lines and impedance stubs, to modify the impedance at the excitation ports, ensuring efficient band rejection. The filter’s performance was thoroughly validated through parametric simulations, followed by the fabrication of a prototype on an FR4 substrate. Measurement results show excellent agreement with simulations, achieving |S11| of -0.56 dB and |S21| of -73 dB at 4 GHz, demonstrating the filter’s ability to deliver high rejection with minimal insertion loss. This BSF not only offers a robust solution for interference mitigation in S and C bands but also stands out for its ease of fabrication and stability, making it a viable option for integration into compact and high-performance communication systems.