Left handed coplanar waveguide band pass filters based on bi-layer split ring resonators

• Published in: IEEE microwave and wireless components letters Vol. 14; no. 1; pp. 10 - 12
• Main Authors: Falcone, F., Martin, F., Bonache, J., Marques, R., Lopetegi, T., Sorolla, M.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-01-2004; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Band pass filters; Bandpass filters; Circuit properties; Coplanar waveguides; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Etching; Exact sciences and technology; Frequency filters; Frequency ranges; Magnetic permeability; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Optical ring resonators; Permeability; Permittivity; Planar waveguides; Resonant frequencies; Resonant frequency; Resonators; Strips; Wire; Waveguide filters; split ring resonators; Ring resonator; Magnetic permeability; Coplanar waveguide (CPW) technology; Band pass filter; microwave filters; Coplanar waveguides; Microwave filter; Permittivity; left handed materials; Planar technology
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2003.821512

A new type of compact band pass filters based on planar structures with three metal levels is proposed. The central layer consists on a coplanar waveguide (CPW) with periodic wire connections between the central strip and ground planes. In the upper and lower metal levels, split ring resonators (SRRs) are etched and aligned with the slots. The wires make the structure to behave as a microwave plasma, with a negative effective permittivity covering a wide frequency range. SRRs, which are magnetically coupled to the CPW, provide a negative magnetic permeability in a narrow frequency range above their resonant frequency. The result is a band pass structure which supports wave propagation in a frequency interval where negative permittivity and permeability coexist. The bandwidth of the structure can be controlled by tuning the resonant frequency of the upper and lower SRRs and the distance between SRRs. Fabricated prototype devices exhibit very low insertion losses in the pass band (<1.5 dB) and high frequency selectivity.