Received: January 10, 2018 29 International Journal of Intelligent Engineering and Systems, Vol.11, No.3, 2018 DOI: 10.22266/ijies2018.0630.04 A Miniature Microstrip BSF Using Complementary Split Ring Resonator Badr Nasiri 1* Ahmed Errkik 1 Jamal Zbitou 1 Abdelali Tajmouati 1 Larbi El Abdellaoui 1 Mohamed Latrach 2 1 Laboratory of Mechanic, Energetic, Electronic and Telecommunication, Faculty of Sciences and Technics, Hassan first university, Morocco 2 Microwave Group, Ecole Supérieure d’Electronique de l’Ouest, Angers, France * Corresponding author’s Email: b.nasiri@uhp.ac.ma Abstract: In this paper, a new microstrip band-stop filter based on a complementary split ring resonator unit cell is proposed, simulated and fabricated on an FR-4 substrate. The design procedure is divided into three sections. Firstly the conventional 3rd Butterworth low-pass prototype a cut-off frequency of 1.2GHz is designed. Secondly, several series of optimisations have been carried out and studied in order to achieve a miniature circuit size, thirdly the low impedance of the miniaturized LPF is replaced by the chosen resonator with a view to obtaining a band-stop behaviour around of CSRR resonant frequency. The simulated and measured results are compared and good agreement is achieved between them. The proposed band-stop filter is characterized by stopband fractional bandwidth of 58% with deep rejection can reach 30 dB at the centre of the rejected band and good electrical performances in the first and second passbands are noticed. This proposed circuit is an adequate solution for the Industrial, Scientific, and Medical band (ISM band) and Universal Mobile Telecommunications System (UMTS IMT-E band). Keywords: Microstrip, Band-stop filter, Metamaterials, Complementary split ring resonator. 1. Introduction Suppression of spurious signals and harmonic interferences produced by the active devices is an essential process in wireless and mobile communication systems [1, 2], this operation is performed by the filters. Which mean that the microwave filters are important and indispensable devices in these systems due to their remarkable and outstanding role [3, 4]. Recently, the demand for compact and miniature planar components characterized by high- electrical performances has rapidly increased [5, 6]. That led to exploring various methods and techniques for achieving the microstrip band-stop filters BSFs with excellent features in term of size, band-stop rejection level, and band-pass insertion loss [7, 8]. Among these technics, Defected ground structure DGS [9, 10], electromagnetic band gap EBG but the EBG- filter circuit size remains relatively large which is one of the most major disadvantages to be solved, more particularly when these filters operate at lower frequencies [11], and metamaterials. Newly, filters based on metamaterials have attracted the attention of scientists and researchers due to their special and unusual characteristics [12, 13]. In 1967, this engineered material was first introduced and theoretically investigated by Veselago [14]. Metamaterial exhibit exceptional and unusual electromagnetic propagation properties are not found in nature and available materials, this artificial structure has a negative permittivity or/and negative permeability in a certain frequency range [15]. After 30 years, Pendry et al proposed the idea to realize a medium have simultaneously negative effective permeability and negative effective permittivity by using Thin-Wires TW and Split Ring Resonators SRRs [16]. The first experimental verification was achieved by smith et al in 2001. These important theoretical and experimental contribution in electromagnetic field and material properties lead to the beginning of study and development of the metamaterials [17]. That give rise