Left-handed Coplanar Waveguide Research Articles

Solitonic rogue waves induced by the modulation instability in a split-ring-resonator-based left-handed coplanar waveguide

Modulation instability and nonlinear excitation modes in lower and upper frequency bands are investigated in the nonlinear left-handed coplanar waveguide, where nonlinear capacitance (voltage-dependent) is used. The multi-scale method is employed to derive a system of two coupled nonlinear Schödinger equations governing the evolution of the kink and bright solitons of these modes. A modulation instability is investigated to show the effects of the left-handed and right-handed influences on the modulation instability gain and the intensity of the plane wave. In the lower and upper frequency modes, the breathing structures have strong values for the left-handed component. At the end, the numerical simulation of the continuous wave is used to show the development of the modulated waves and localized objects. Another relevant localized structure has been obtained to display the second-order breathers and Akhmediev breathers of types A and B under the variation of the perturbed wave number. Both linear inductances and perturbed wave numbers are tools for controlling the amplitude of the localized structures, and modulation instability is sensitive to these parameters.

Quasidiscrete microwave solitons in a split-ring-resonator-based left-handed coplanar waveguide

We study the propagation of quasidiscrete microwave solitons in a nonlinear left-handed coplanar waveguide coupled with split-ring resonators. By considering the relevant transmission line analog, we derive a nonlinear lattice model which is studied analytically by means of a quasidiscrete approximation. We derive a nonlinear Schrödinger equation, and find that the system supports bright envelope soliton solutions in a relatively wide subinterval of the left-handed frequency band. We perform systematic numerical simulations, in the framework of the nonlinear lattice model, to study the propagation properties of the quasidiscrete microwave solitons. Our numerical findings are in good agreement with the analytical predictions, and suggest that the predicted structures are quite robust and may be observed in experiments.

The research of equivalent circuit of left-handed coplanar-waveguide transmission line element

In this paper, a new type of left-handed (LH) transmission line is proposed. It is composed of a parallel embedded inductance and a series interdigital capacitor based on a coplanar-waveguide (CPW) transmission line. According to medium theory, the effective permittivity and permeability of LH CPW transmission line have been extracted. The characteristics of LH transmission line have been verified by calculating β parameter of the CPW transmission line. Then, an equivalent circuit model of LH CPW transmission line is extracted and the validity of the model is demonstrated by full-wave simulation.

Numerical Simulations of Backward-to-Forward Leaky-Wave Antenna with Composite Right/Left-Handed Coplanar Waveguide

A composite right / left-handed (CRLH) coplanar waveguide (CPW) structure and its leaky-wave antenna (LWA) with continuous backward-to-forward scanning applications are proposed. The structure of the CRLH transmission line (TL) is composed of split-ring resonators (SRRs) for left-handed (LH) series capacitance and short-circuited stubs connected between the CPW central signal line and the ground for LH shunt inductance, while the unavoidable right-handed (RH) parasitic effects series inductance and shunt capacitance are generated by wave propagation through the host transmission line. The dispersion relations are calculated and compared with the equivalent circuit model method and 3D full-wave simulations, which can be used to determine the physical dimensions of the CRLH-CPW, such as in the balanced CRLH-TL case. As a main example, a CRLH-CPW-LWA operating from 1.67 GHz to 1.80 GHz with the dispersion characteristics of the balanced CRLH-TL case shows continuous leakage frequency band (fast wave region) from LH (phase constant β < 0, 1.67 < f < 1.74 GHz) to BH (β > 0, 1.74 < f < 1.80 GHz) state through the transition frequency point (β = 0, f = 1.74 GHz), whereas conventional LWAs operated in RH state only provide forward scanning capabilities (β > 0).

Neural Model for Left-Handed CPW Bandpass Filter Loaded Split Ring Resonator

Compact left-handed coplanar waveguide (CPW) bandpass filter loaded split ring resonator (SRR) is presented in this paper. The proposed filter exhibits a quasi-elliptic function response and its circuit size occupies only 12 × 11.8 mm2 (≈0.21 λg × 0.20 λg). Also, a simple circuit model is given and the parametric study of this filter is discussed. Then, with the aid of NeuroModeler software, a five-layer feed-forward perceptron neural networks model is built up to optimize the proposed filter design fast and accurately. Finally, this newly left-handed CPW bandpass filter was fabricated and measured. A good agreement between simulations and measurement verifies the proposed left-handed filter and the validity of design methodology.

Compact Tunable Left Handed Ferrite Transformer

In this paper, a novel compact and tunable impedance transmission line transformer is presented for the first time. The transformer is designed using a left handed coplanar waveguide transmission line on a ferrite substrate. Based on the dispersive properties of the ferrite medium, the theoretical study of the transformer has been carried out using its equivalent circuit analysis and the composite right / left handed transmission line theory. The theoretical study was verified through full wave electromagnetic numerical simulations. The results show that the transformer matches a 25 Ω load to a 50 Ω line with tunability from 2.55 GHz to 3.2 GHz. The return loss at center frequency is better than 20 dB with insertion loss better than -1 dB. The transformer has a very compact size with dimensions of 4.25 × 21 mm2, showing approximately 64% reduction in size in comparison with a conventional right-handed transformer within the same operating frequency band. Moreover, the proposed coplanar waveguide transformer configuration has smaller demagnetization factor and hence it requires smaller DC magnetic bias values compared to microstrip configuration.

Compact tuneable single and dual mode ferrite left-handed coplanar waveguide coupled line couplers

For the first time, single and dual mode novel left-handed coupled line couplers implemented on ferrite substrates are reported. Both of the proposed couplers demonstrate novel characteristics of coupler operation with properties of tunability and non-reciprocity, which have not been demonstrated before. The proposed couplers are realised in a left-handed coplanar waveguide configuration, constructed using interdigital capacitors and various types of planar shunt inductors. The performance of the couplers has been studied theoretically and verified numerically. The single mode tuneable coupler demonstrates a coupling level as high as 4 dB with a maximum isolation level better than 25 dB. The dual mode tuneable coupler exhibits non-reciprocal operations with a near-zero dB coupling level and a maximum non-reciprocal isolation level of more than 30 dB. Moreover, both the couplers have very compact sizes: 10.32 mm times 19.8 mm for the single mode coupler and 10.2 mm times 19.8 mm for the dual mode tuneable coupler, respectively.

Multi-Band Functional Tunable LH Impedance Transformer

This paper presents, for the first time, the analysis and design performance of tunable left handed coplanar waveguide transformer designed on a ferrite substrate. The proposed transformer is studied analytically and verified numerically. Results show that the proposed transformer has tunable dual band of operation with frequency tuning range from 2.35 GHz to 3.85 GHz with return loss from 10 dB to 25 dB. Such tunability can be achieved by changing the DC magnetic bias. The advantages of the proposed transformer are its tuning capability, its multi functionality operation, and its compact size.

Design and Analysis of Tunable Left Handed Zeroth-Order Resonator on Ferrite Substrate

This paper presents, for the first time, a tunable left handed coplanar waveguide zeroth-order resonator on a ferrite substrate. Analysis and design procedures of the proposed resonator are introduced. The proposed resonator is designed to be tuned over the frequency band from 3 to 4.85 GHz with lower than 3-dB insertion loss and better than 10-dB return loss. The dimensions of the proposed resonator are 8.3 times 20 mm. The advantages of the proposed resonator are its tuning capability in addition to its compact size.

Nonreciprocal left handed coplanar waveguide over ferrite substrate with only shunt inductive load

AbstractA novel ferrite nonreciprocal left‐handed (LH) transmission line is presented. The proposed structure is composed of a coplanar waveguide over a ferrite substrate, horizontally magnetized and periodically loaded with only shunt inductors. The line has a nonreciprocal LH propagation with transmission level better than −5 dB with isolation level up to 20 dB over a moderate bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2810–2814, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22848

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

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.

Split ring resonator-based left-handed coplanar waveguide

In this letter, a planar left-handed propagating medium consisting of a coplanar waveguide (CPW) inductively coupled to split ring resonators (SRR) and periodically loaded with narrow metallic wires is proposed. The wires make the structure behave as a microwave plasma with a negative effective permittivity which covers a broad frequency range. The negative permeability required to achieve left-handed wave propagation is provided by the rings in the vicinity of their resonant frequency. The result is a structure which allows negative wave propagation in a narrow frequency band. The transmission coefficient measured in a fabricated prototype device exhibits very low insertion losses in the pass band and high-frequency selectivity. Since rings are much smaller than signal wavelength at resonance and can be easily tuned, SRR-CPW-based structures are of interest for the design of very compact microwave circuits based on left handedness.