Javier Mata-Contreras

Miniature Microwave Notch Filters and Comparators Based on Transmission Lines Loaded with Stepped Impedance Resonators (SIRs)

In this paper, different configurations of transmission lines loaded with stepped impedance resonators (SIRs) are reviewed. This includes microstrip lines loaded with pairs of SIRs, and coplanar waveguides (CPW) loaded with multi-section SIRs. Due to the high electric coupling between the line and the resonant elements, the structures are electrically small, i.e., dimensions are small as compared to the wavelength at the fundamental resonance. The circuit models describing these structures are discussed and validated, and the potential applications as notch filters and comparators are highlighted.

Modeling Metamaterial Transmission Lines Loaded With Pairs of Coupled Split-Ring Resonators

A lumped-element equivalent circuit model of the unit cell of metamaterial transmission lines loaded with pairs of coupled split-ring resonators (SRRs) is presented. It is assumed that the dominant coupling mechanism between the SRRs forming the pair is magnetic, and that the distance between SRRs of adjacent cells is high enough to neglect such additional inter-resonator coupling. SRRs are oriented with their symmetry plane orthogonal to the line axis. Under these conditions, the line-to-SRR coupling is also magnetic, the electric coupling being negligible. The presented model accounts for the rupture of symmetry that can be caused, for instance, by asymmetric dielectric loading of the SRRs. Thus, the analysis is carried out on a general model where the SRRs of the pair have different inductance and capacitance. Then, different cases are studied, in particular a line with identical SRRs, and a line with different SRRs, but with the same resonance frequency. It is shown that coupling between SRRs tends to far or split the resonance frequencies of the loaded lines (transmission zeros), except for the symmetric case, where only one resonance (different to the one of uncoupled SRRs) appears. The model is validated by comparing circuit simulations using extracted parameters with electromagnetic simulations and experimental data.

Modeling and Applications of Metamaterial Transmission Lines Loaded With Pairs of Coupled Complementary Split-Ring Resonators (CSRRs)

This letter is focused on the modeling, analysis, and applications of microstrip lines loaded with pairs of electrically coupled complementary split-ring resonators (CSRRs). Typically, these epsilon-negative (ENG) metamaterial transmission lines are implemented by loading the line with a single CSRR (etched beneath the conductor strip) in the unit cell. This provides a stopband in the vicinity of the CSRR resonance. However, by loading the line with a pair of CSRRs per unit cell, it is possible to either implement a dual-band ENG transmission line (useful, for instance, as a dual-band notch filter), provided the CSRRs are tuned at different frequencies, or to design microwave sensors and comparators based on symmetry disruption (in this case by using identical CSRRs and by truncating symmetry by different means, e.g., asymmetric dielectric loading). The design of these CSRR-based structures requires an accurate circuit model able to describe the line, the resonators, and the different coupling mechanisms (i.e., line-to-resonator and inter-resonator coupling). Thus, a lumped element equivalent circuit is proposed and analyzed in detail. The model is validated by comparison to electromagnetic simulations and measurements. A proof-of-concept of a differential sensor for dielectric characterization is proposed. Finally, the similarities of these structures with coplanar waveguide transmission lines loaded with pairs of SRRs are pointed out.

Ultra-Compact (80

This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm × 7.6 mm.

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Distributed mixers are based on the active coupling of two artificial transmission lines (TLs) and provide ultra-wideband performance. This paper shows that it is possible to design distributed mixers with novel performances if artificial TLs with dispersion diagrams different from those provided by conventional series-inductor/shunt-capacitor TLs are used. In particular, three novel distributed mixers, presenting dual-band/diplexer behavior, with and without image rejection or wideband conversion response with image rejection, are proposed, analyzed, and measured. An ideal continuous model is used to analyze the intrinsic behavior of distributed mixers and to show how to engineer their desired performance by proper design of the phase constants. The limitations derived from the unavoidable discrete implementation of the artificial TLs are also assessed. Finally, three mock-ups are implemented and measured. The experimental results obtained proof these novel distributed mixer concepts and validate the proposed theoretical analysis and design methodology.

) Differential-Mode Ultra-Wideband (UWB) Bandpass Filters With Common-Mode Noise Suppression

Spectral signature barcodes functional at the

Active Distributed Mixers Based on Composite Right/Left-Handed Transmission Lines

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Multistate Multiresonator Spectral Signature Barcodes Implemented by Means of S-Shaped Split Ring Resonators (S-SRRs)

frequency band are presented in this paper. The barcodes are implemented by loading a coplanar waveguide transmission line by means of multiple S-shaped split ring resonators (S-SRRs), each one tuned to a different frequency. The main particularity of this paper is the fact that more than two logic states (i.e., three or four, depending on the implementation) are assigned to each resonant element. By this means, the total number of bits of the barcode (for a given number of resonators) is increased, as compared with previous approaches based on two logic states per resonator. This multistate functionality is achieved by rotating the S-SRRs. Such rotation modulates the line-to-resonator coupling intensity, and consequently the notch depth at the S-SRR fundamental resonance. Therefore, by considering three or four fixed rotation angles (or orientations) between the line axis and the S-SRR (for the tri- and four-state multiresonator barcodes, respectively), intermediate levels between the maximum and minimum attenuation are achieved. This multistate strategy only exploits a single frequency per resonant element (the fundamental one). Therefore, the data capacity per bandwidth are improved as compared with two-state-based barcodes or to multistate barcodes that use two frequencies per resonant element. As illustrative examples, two different four-state multiresonator barcodes with eight S-SRRs (providing

Splitter/Combiner Microstrip Sections Loaded With Pairs of Complementary Split Ring Resonators (CSRRs): Modeling and Optimization for Differential Sensing Applications

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Transmission Lines Loaded With Pairs of Stepped Impedance Resonators: Modeling and Application to Differential Permittivity Measurements

different codes, or 16 bits) and with nine S-SRRs (equivalent to 18 bits), occupying a spectral bandwidth of 1 GHz and less than 6.75 and 8.2 cm2, respectively, are designed, fabricated, and characterized.