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In this paper, a circuit model for the description of left handed transmission lines based on complementary split rings resonators (CSRRs) is proposed. As compared to previous models, coupling between adjacent resonators is included in the present work. The conditions that make this coupling significant are discussed. Specifically, it will be shown that it is barely present when circular CSRRs are used to implement the left handed transmission line. However, if the line is loaded with rectangular CSRRs separated by a small distance, inter-resonator coupling is important and it significantly influences the electromagnetic behavior of the structures. It will be also shown that under low or moderate coupling, it is possible to describe the structures by means of a simplified model with modified parameters. Several prototype devices with different CSRR topologies and coupling levels have been fabricated to illustrate the phenomenology associated with these structures and the accuracy of their model descriptions. The results of this work can be of interest for the design of planar microwave circuits based on CSRR left handed lines. [ABSTRACT FROM AUTHOR]

A new design approach for compact microstrip band-pass filter based on semi-lumped resonators are proposed. The resonators, which are coupled through quarter wavelength meander lines acting as admittance inverters, are shunt connected to the line. They consist of parallel combination of a grounded (inductive) stub and a narrow metallic strip followed by a capacitive patch to ground. With this topology, the necessary degree of flexibility to design narrow and broad-band-pass filters with compact dimensions and good out-of-band performance was obtained. Another key advantage of the devices, as compared to previous lumped or semi-lumped element-based structures reported by the authors, is the absence of ground plane etching. To illustrate the potentiality of the proposed approach, a third-order (30% fractional bandwidth) and a nineth-order (35% fractional bandwidth) Chebyshev band-pass filters have been designed and fabricated. The measured frequency responses are very symmetric and exhibit low in-band losses as well as good out-of-band rejection up to approximately 3fo. Filter dimensions are as small as $0.40\lambda \times 0.12\lambda$ (third-order prototype) and $0.62\lambda \times 0.16\lambda$ (nineth-order prototype), λ being the guided wavelength at fo. With these dimensions and performance, and the possibility to synthesise microstrip filters with controllable bandwidth over a wide margin, it is believed that the reported approach can be of actual interest for the design of planar filters at microwave frequencies. [ABSTRACT FROM AUTHOR]

In this paper, the transmission properties of left-handed microstrip lines implemented by etching complementary split rings resonators (CSRRs) and capacitive gaps in the ground plane and conductor strip, respectively, are investigated. To this end, we make use of the lumped element equivalent circuit model of the structure, from which an accurate analysis is carried out, and the influence of the main electrical parameters on the transmission properties is pointed out through electrical simulations. Aspects such as bandwidth and in-band ripple control are discussed in detail. The influence of the geometrical parameters is also discussed and interpreted to the light of the equivalent circuit model. From the results obtained, there are inferred design guidelines that are suitable for the design of metamaterial transmission lines subjected to specifications. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the potential use of complementary split-ring resonators (CSRRs) to design very compact waveguide filters, by etching a CSRR in the center of a metallic sheet, is demonstrated. This original layout reduces the dimensions of the well-known resonant-cavity waveguide filters coupled by irises. This has been made feasible due to the self-resonance property of the CSRR. Thus, it is possible to design waveguide filters with lengths equal to the thickness of a metallic sheet. Consequently, this technique paves the way for the design of miniaturized waveguide filters, in contrast to conventional waveguide filters, based on bulk resonators. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 88–92, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20909 [ABSTRACT FROM AUTHOR]

In this paper, it is demonstrated that split-ring resonators (SRRs) magnetically coupled to a coplanar waveguide (CPW) structure can be applied to the design of miniaturized band-pass filters. To this end, a two-stage prototype device consisting of a CPW with two signal-to-ground shorts and a series gap, combined with SRRs, is designed and fabricated. By virtue of the subwavelength operation of SRRs at their quasi-static resonance, the filter dimensions can be made to be very small in comparison to conventional distributed implementations. Other relevant features of the proposed structures are: (i) low insertion losses (<3.5 dB) in the allowed band, (ii) out-of-band rejection levels above 30 dB, and (iii) very sharp transition slopes. It is believed that these SRR-based structures can be of interest for the design of planar filters with potential application in future communication transceivers. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 33–35, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20893 [ABSTRACT FROM AUTHOR]

Coplanar waveguide (CPW) transmission lines periodically coupled to spiral resonators (SRs) are proposed to obtain very compact band-pass or rejection-band structures. The devices consist of a CPW with SRs etched on the back substrate side, underneath the slots. Due to inductive coupling between the line and the spirals, signal propagation is inhibited in the vicinity of the resonant frequency, resulting in a stop-band structure. However, by periodically loading the line with narrow wires, this behavior is switched to a band-pass characteristic. This has been interpreted as being due to the coexistence of a negative effective permittivity and permeability in a narrow band above resonance for the composite structure. Since the dimensions of the spirals are very small in comparison to the signal wavelength at resonance, these devices are very compact and can be of interest in applications where miniaturization is mandatory. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 386–388, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20312 [ABSTRACT FROM AUTHOR]

A new topology for the design of microstrip microwave diplexers, based on the use of quasi-lumped resonators, is presented. Specifically, the receiver (Rx) and transmitter (Tx) filters of the diplexer are implemented by etching complementary split ring resonators (CSRRs) in the ground plane as well as series capacitive gaps and shunt inductive strips in the upper metal level. By this means, narrowband microwave diplexers with transmission zeros can be synthesised, which allow for the improvement of Rx/Tx isolation. A prototype device operative in the 2.4-3.0 GHz frequency band is presented. Measured insertion losses are lower than 2 dB while the isolation between Rx/Tx channels is in the vicinity of 40 dB. Diplexer dimensions (29.8 × 16.3 mm), which are small on account of the semi-lumped resonators employed, and performance point to the practical application of these structures in communication transceiver front-ends. [ABSTRACT FROM AUTHOR]