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A 2% bandpass filter with an out-of-band rejection in excess of 30 dB was demonstrated experimentally for operation in the C-band (central frequency at 4.5 GHz). Narrow bandwidth and high rejection were achieved by cascading three double split-ring resonators (SRRs) magnetically coupled to a coplanar waveguide (CPW) and three pairs of shunt wires between the central strip and the ground metal layers. This configuration, directly inspired from the so-called metamaterial technology, takes advantage of the high dispersion of the loaded transmission line, induced by a negative magnetic response via the resonators, and of a negative permittivity effect via the shunt wires. The optimization of: 1) the symmetry; 2) the out-of-band rejection; and 3) the fractional bandwidth was carried out in two stages, i.e., by engineering the plasma frequencies of the electrical and magnetic systems and by tapering the tightly coupled cascaded unit cells in order to achieve an overlap of their individual responses.

In this letter, the design and comparative study of metamaterial-inspired bandpass filters operating at G-band (150 GHz) is presented. To this aim, filters based on split ring resonators (SRRs) and complementary SRRs are studied and compared on a scale compliant with MMIC technology. Technological issues impose severe constraints to the design of this type of devices. Specifically, the filter selectivity concern is addressed as a trade-off between the acceptable insertion losses in the transmitted band and the achievable bandwidth. The addition of series gaps to previous unit cell configurations and suspended membrane structures are introduced to overcome these limitations, thus presenting improved upper band edges and rejection characteristics. In this context, the extension of metamaterial-based filtering structures to higher frequencies and notably at millimeter waves is still lacking. Therefore, we present here the first contribution in this field by addressing the possibility to fabricate an ultra narrow bandpass filter for space applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1868–1872, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25300

International audience; In this study, two split ring resonator-based coplanar waveguide cells operating in C-band are studied. Particularly, the lines have been loaded with double shunt strips or series gaps. The use of double strips allows controlling the electric plasma frequency, and at the same time permits one to have a good excitation of the resonators. On the other hand, the employment of double series gaps provides a right-handed behaviour, contrary to conventional metamaterial structures for which a backward propagation is obtained. Several parametric studies show the possibility to significantly increase the selectivity, and in particular the possibility to have an effective control on the out-of-band rejection levels by means of the loading elements characteristics. In a second stage, enhanced out-of-band rejection properties have been obtained by the use of cascaded basic cells and rigorous optimization processes. As a consequence, the proposed filters can be foreseen for practical applications relying on the trade-off found between selectivity, insertion losses and out-of-band rejection.

Dipole loaded with left handed transmission lines allows operation with higher order mode current distributions and small size. Use in a meandered configuration can give polarisation orthogonal to the dipole length. In this paper a new printed implementation using distributed elements is proposed with improved efficiency. Comparisons are made between this antenna and previous antenna structures implemented with lumped and distributed elements, consisting of interdigitated capacitors and meandered line inductors. The simulated results show good input impedance match and radiation pattern typical of a dipole. This antenna also achieved an improved radiation efficiency of 73.84% and a gain of 0.809 dBi was obtained. Experimental results validate the performance of this antenna. (4 pages)

The frequency selectivity of coplanar transmission lines loaded with split ring resonators and shunt strips was dramatically improved owing to a blueshift of the electrical plasma frequency by oversizing the strip width. Beyond a higher rejection level, which was expected as a consequence of the deepening of the forbidden gap between the left- and right-handed dispersion branches, a huge enhancement in the loaded Q quality factors, while maintaining low insertion losses were also pointed out. This Q factor improvement was a consequence of a decrease in the coupling between the resonators and the transmission line.

International audience; A coplanar waveguide line based on a split ring resonator technology and loaded with metallic strips and capacitances is proposed. The addition of series capacitances to previous unit cell implementations dramatically improves the upper band rejection levels and provides a transmission response almost symmetric. The configuration also exhibits a band pass response with a right-handed character as a result of the balance between advance and delay phase offsets contrary to the conventional left-handed lines. The interpretation is based on an equivalent circuit model, full-wave electromagnetic analysis, and measured responses of a prototype designed for microwave operation

This paper presents a printed dipole with left-handed loading and electrically small dimensions. Uniform currents are obtained at 750MHz, proving zero order (i.e., n = 0) mode operation. Comparisons are made with other left- and right-handed antennas. Good agreement is achieved between simulation and measurement. The antenna has various applications in RFID systems and wireless environments.