International Journal of Electrical and Computer Engineering (IJECE) Vol. 14, No. 4, August 2024, pp. 4128~4137 ISSN: 2088-8708, DOI: 10.11591/ijece.v14i4.pp4128-4137  4128 Journal homepage: http://ijece.iaescore.com A novel configuration of a microstrip metamaterial reconfigurable bandstop filter Amina Aghanim 1 , Otman Oulhaj 1 , Jamal Zbitou 2,3 , Aziz Oukaira 4 , Ahmed Lakhssassi 4,5 , Rafik Lasri 1 1 TEDAEEP Research Team, Faculty Polydisciplinary Larache, Abdelmalek Essaâdi University, Tetouan, Morocco 2 Laboratory of Information and Communication Technologies (LabTIC), National School of Applied Sciences (ENSA) Tangier, Abdelmalek Essaâdi University, Tetouan, Morocco 3 National School of Applied Sciences of Tetouan (ENSATe), Abdelmalek Essaâdi University, Tetouan, Morocco 4 Department of Electrical and Computer Engineering, University of Quebec, Outaouais, Canada 5 Department of Electrical and Computer Engineering, University of Sherbrooke, Sherbrooke, Canada Article Info ABSTRACT Article history: Received Dec 28, 2023 Revised Apr 2, 2024 Accepted Apr 16, 2024 This paper presents the design, simulation, and test measurements of a microstrip bandstop filter operating at 1.5 GHz, incorporating six split ring resonator (SRR) unit cells. The substrate employed is an FR-4 with a thickness of 1.6 mm and tangent losses of 0.025. In the initial phase, the design is conceptualized, simulated using computer simulation technology (CST) studio and advanced design system (ADS) Agilent simulators, and validated through test measurements. Building upon this foundation, the filter is transformed into a reconfigurable variant by integrating four SMV2019 varactor diodes. These varactors are modeled to ensure the reconfigurability of the bandwidth. The integration of varactors introduces dynamic tuning capabilities to the considered bandstop filter. Keywords: Filter Reconfigurable Split ring resonator Stopband Varactor This is an open access article under the CC BY-SA license. Corresponding Author: Amina Aghanim TEDAEEP Research Team, Faculty Polydisciplinary Larache, Abdelmalek Essaâdi University Tetouan, Morocco Email: amina.aghanim@etu.uae.ac.ma 1. INTRODUCTION The escalating demand in the radio frequency (RF) and microwave domain, fueled by applications in wireless communications, internet of things (IoT) technology, radar systems, and cognitive radio [1]–[5], has introduced challenges such as interferences and signal quality reduction. These issues saturate the frequency spectrum, hindering the optimal deployment of RF and microwave technologies. In response, advanced filtering mechanisms are imperative. RF bandstop filters, particularly in microstrip technology, emerge as a promising solution, offering flexibility for integration into compact devices while ensuring optimal filtering performance [6]. These filters are not only cost-effective but also easy to fabricate, addressing challenges in the development and deployment of RF and microwave technologies. Microstrip technology leverages metamaterial properties for the design of optimized bandstop filters [7]–[10]. Metamaterials, engineered with artificial complex geometries, yield unique properties, including negative permittivity and permeability. The historical development of metamaterials, from Veselago's theoretical work in 1986 to Pendry's introduction of the split ring resonator in 1999, laid the foundation for innovative approaches to RF filtering [11]–[13]. The recent focus on reconfigurable filters represents a significant shift from traditional static filters. Reconfigurability, achieved through continuous and discrete avenues, addresses crucial parameters such as bandwidth, center frequency, poles, zeros, and quality factors [14]–[16]. This pursuit is motivated by the