INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS Int. J. Numer. Model. (2011) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jnm.808 Modeling tunable band-pass filters based on RF-MEMS metamaterials Marta Morata 1 , Ignacio Gil 2,Ã,y and Rau´l Ferna´ndez-Garcı´a 2 1 Escuela Universitaria Salesiana de Sarria ´ (EUSS), Pg Sant Joan Bosco 74 08017, Barcelona, Spain 2 Department of Electronic Engineering, Universitat Polite `cnica de Catalunya, Terrassa, Barcelona 08222, Spain SUMMARY This work describes progress toward designing and modeling reconfigurable band-pass filters based on RF microelectromechanical systems (RF-MEMS) metamaterials. A device consisting of a coplanar waveguide structure that combines complementary split ring resonators (CSRRs) and RF-MEMS varactor bridges, operating at K and Ka-band, is proposed. Several layouts have been designed and electromagnetically (EM) simulated. A full equivalent-circuit model for the description of the proposed structure, including transmission lines, RF-MEMS, subwavelength resonators and coupling parameters, is provided. A high degree of accuracy between EM simulations behavior and electrical model has been obtained. Copyright r 2011 John Wiley & Sons, Ltd. Received 20 July 2010; Revised 14 January 2011; Accepted 1 February 2011 KEY WORDS: RF-MEMS; reconfigurable filters; complementary split rings resonators (CSRRs); metamaterials; electromagnetic simulation; electrical model 1. INTRODUCTION The research on reconfigurable band-pass filters based on RF microelectromechanical systems (RF-MEMS) bridges has increased significantly in the last years due to the good performance of RF-MEMS as switches and varactors. In fact, RF-MEMS present very low loss, high-Q and outstanding linearity [1]. These devices are typically implemented by several lithographic steps, which perform RF-MEMS in conventional transmission lines (TLs). Typically, RF-MEMS filters design are carried out by loading a TL periodically with RF-MEMS bridges, forming a distributed MEMS TL [2]. Alternatively, metamaterial TLs (i.e. artificial lines consisting of a host line loaded with reactive elements) have been revealed as good candidates in order to improve the performance of conventional microwave filters [3]. Recently, several tunable band- pass filters based on metamaterials have been developed in PCB [4]. Efficient electrical models of microwave components and devices are crucial in order to design filter implementations in many areas such as signal processing, wireless communications or biomedical engineering. According to the state of the art, several works have been developed to achieve accurate electrical models in order to reproduce frequency responses of RF-MEMS tunable filters [5] and tunable metamaterial TLs in PCB [6]. To the best knowledge of the authors, some few works have presented the combination of RF-MEMS and metamaterials in with the aim to implement reconfigurable filters [7, 8]. *Correspondence to: Ignacio Gil, Department of Electronic Engineering, Universitat Polite` cnica de Catalunya, Terrassa, Barcelona 08222, Spain. y E-mail: gilgali@eel.upc.edu Copyright r 2011 John Wiley & Sons, Ltd.