Composite Right/left-handed Research Articles

Matrix Power Amplifier With Open-Circuit Composite Right-/Left-Handed Transmission Line

A distributed matrix power amplifier with open-circuit (O.C) composite right-/left-handed (CRLH) transmission line (TL) is proposed. The matrix structure along with the zero phase-shift CRLH TL and the O.C termination of TLs have led to the design of reduced size, high-gain matrix amplifier with improved power performances. A new small size planar CRLH unit cell is presented. The maximum gain of 21.5 dB at the center frequency is obtained. The measured 1-dB gain compression (P1-dB) is 26 dBm, and the maximum power added efficiency is 29%. Better gain and P1-dB are achieved compared to the previously published narrowband distributed amplifiers. The amplifier has good linearity according to the measured input intercept point (18 dBm) and the output intercept point (39 dBm).

Compact quad‐band second harmonic antenna based on metamaterial DRA load

AbstractWe have developed a compact antenna for wireless applications with a new shape and special attribute. It is a dual‐band antenna with a second harmonic characteristic. The antenna has a special shape of the dielectric resonator with metamaterial meandered composite right/left‐hand (CRLH) structure. The Microstrip ring antenna is the right‐hand part. We used the Microstrip meandered line via inductance for the unit cells to achieve a circular polarization and to change the current distribution at the surface of the antenna. We added a parasitic ring to the antenna to achieve the second harmonic resonance. We have connected three unit cells at the 120° angle. This special shape provides the circular polarization and compact size. The antenna has quad‐band at the first harmonic, and the resonances occurred at 2.25 and 2.8 GHz. The second harmonics happened at 4.5 and 5.6 GHz.

Single-Layer Multi-Via Loaded CRLH Leaky-Wave Antennas for Wide-Angle Beam Scanning With Consistent Gain

Achieving continuous backward-to-forward wide-angle beam scanning with consistent gain by employing composite right/left-handed (CRLH) leaky-wave antennas (LWAs) is reported. For structural and design simplicity, a single-layer one-dimensional structure is considered in which each unit cell consists of a patch shorted centrally to the ground plane. It was found that, when using only one via at the center of a unit cell, a continuous beam scan requires a large-diameter via when all other parameters remain unchanged. To eliminate this limitation while maintaining a single-layer structure, novel unit cells are proposed using multiple vias in each unit cell. An LWA design for continuous beam scan with three vias in each unit cell is investigated, and the results show good performance and design flexibility. A prototype antenna has been realized, and the measured results show that the antenna can scan the radiation beam continuously in a wide range, from −60° to +66° with a consistent gain. The measured gain variation within the scan range is only 2.9 dB, and the 3 dB gain bandwidth is 58.6%.

Design of CRLH Leaky-Wave Antenna With Low Sidelobe Level

Composite right/left-handed (CRLH) waveguide leaky-wave antenna (LWA) with low sidelobe level (SLL) and high radiation efficiency is investigated and designed in this paper. Due to the characteristic of negative and positive dominant mode propagation constant of the CRLH transmission line, a backward to forward beam-steering LWA can be realized through frequency scanning. The leaky-wave radiation is analyzed first based on a Ka-band CRLH waveguide with straight slots differently offset on the broadwall. The propagation constant maintains almost invariable as the slot offset varies, meanwhile the attenuation constant has a considerable dynamic range. Thus meandering long slot, whose offset varies along the CRLH waveguide, can be cut on the broadwall to generate a tapered excitation distribution. A prototype of the proposed CRLH waveguide LWA with meandering long slot is designed and fabricated to validate the design. Measurement results show that continuous beam-steering capability from −29° to +31° is achieved, meanwhile the optimized SLLs for the designed antenna patterns are kept below −18.5 dB in the major operating band with the minimum SLL of −22.4 dB at 33 GHz, and the average radiation efficiency is 65.4%. The realized SLLs and radiation efficiency performances of our CRLH LWA surpass others reported in open literatures.

Application of the Scattering Bond Graph Methodology for Composite Right/Left Handed Transmission Lines

The approach of the metamaterials based on the theory of transmission lines has an influence on the development of the radiofrequency domain, so the types and techniques of elaboration of these artificial lines are quite diversified. This paper will present two models of Artificial Transmission Line CRLH (Composite Right Left Handed) composed of a combination of resonators OSRR (Open Split Ring Resonators) and OSCRR (Complementary Open Split Ring Resonators). This paper will also show how the Scattering Bond Graph (SBG) study methodology allows to provide electromagnetic simulation results (Scattering parameters, phase response) more conducive to Bond Graph (BG) modeling, and will prove the possibility of having the most perfect line (solved the problem of impedance adaptation) and better understanding of the behavior of radiofrequency systems.

Design and Fabrication of VHF Band Small Antenna Using Composite Right/Left-Handed Transmission Lines

This paper presents a small VHF antenna using a composite right/left-handed (CRLH) transmission lines. The proposed antennas have 3 and 7 unit cells that consist of interdigital capacitors and shunt spiral inductors. The size of the antenna with 3 unit cells is 0.039λ × 0.025λ × 0.0008λ (72.9 × 47.5 × 1.52 mm3) at 161 MHz and its peak gain is − 33 dBi. To enhance the gain, the antenna with 7 unit cells is fabricated. Its size is 0.089λ × 0.025λ × 0.0008λ (167.2 × 47.5 × 1.52 mm3) at 161.4 MHz and its peak gain is − 26.5 dBi. The radiation pattern of both antennas is omni-directional. The electrical size in kr of each antenna is 0.055 and 0.11, respectively. The effects of frequency characteristic of lumped elements on the impedance matching are discussed.

Design of Compact Tri-Band Gysel Power Divider With Zero-Degree Composite Right-/Left-Hand Transmission Lines

In this paper, a tri-band Gysel power divider (PD) based on zero-degree composite right-/left-handed (CRLH) transmission lines (TLs) is presented. Compared to the generalized design methods in which multiple passbands are realized by replacing conventional impedance transformers with quarter-wavelength CRLH-TLs, the employed zero-degree CRLH-TLs include high design flexibility for the characteristic impedance and phase responses of the composed left-handed and right-handed TLs, which can be used to separately control the bandwidths of the three passbands. In addition, the microstrip-to-slotline transition is utilized to replace the conventional 180° TL, which can expand the realizable range of the three center frequencies and reduce the circuit size, as well. The proposed theory is validated using two designs: One involves a broadband PD with a center frequency of 2.5 GHz, while the other is a tri-band PD centered at 3.5 GHz, 2.5 GHz, and 1.5 GHz. Good agreement between the simulated and measured results are obtained; for the first PD, a fractional 3-dB bandwidth of up to 116% is achieved, whereas, for the tri-band PD, a size reduction of 80% is achieved with good impedance matching and isolation performance.

Compact Frequency Reconfigurable Antennas Based on Composite Right/Left-Handed Transmission Line

The compact reconfigurable antennas based on composite right/left-handed (CRLH) transmission line are proposed and analyzed in this paper. The proposed antenna is fed by the asymmetric coplanar strip (ACPS) and consists of coupling radiation patch as well as a PIN diode. The differences of the antennas with meander line and without meander line are discussed. By utilizing a PIN diode as the CRLH transmission line termination, the termination states can be controlled, and the resonance of the antenna can thus be tuned between the two zeroth-order resonant frequencies. By switching the diode, the antenna with meander line is able to operate in single-band of 2.08-2.54 GHz and dual-bands of 1.65-1.84 GHz and 5.35-6.40 GHz, while the antenna without meander line is able to operation between two single-bands of 1.84-2.28 GHz and 4.6-6.0 GHz. All these operation bands cover the UMTS (1750 MHz-1780 MHz), ISM (2.4 GHz), WIMAX (2.5-2.69 GHz) and WLAN (2.4-2.484 GHz/5.725-5.825 GHz) applications. The radiation performance was simulated by High Frequency Structure Simulator, and the measurements were taken in an anechoic chamber to verify the simulation results. Good agreements are observed between the simulated and measured results. Moreover, the radiation patterns of the proposed antennas remain stable at different reconfigurable bands.

CRLH-Transmission Line for Design and Analysis of Compact Microstrip Patch Antenna

The composite right/left-hand transmission line is displayed as an ordinary Transmission Line having two type of properties, first one left-hand properties and second one right-hand properties. By demonstrating a metamaterial based CRLH as a comparing TL, TL hypothesis can be utilized for analysis and plan one-, two-, or even three-dimensional CRLH metamaterials. The structure of CRLH-TL has the arrangement of metamaterial transmission line (TL) made out clearly by composite right-/left-hand (CRLH) unit cells. The Composite Right Left Handed (CRLH) transmission lines are on recent displayed as a kind of artificial transmission lines with various microwave applications. This examination take a gander at various types of execution of these transmission lines and the impact over the execution. The examination is passed on utilizing both lumped parts and microstrip utilization of the unit cells. As a summed up, show for CRLH TL provides for an incredible level of excellent stage reaction, for instance, double band task, nonlinear frequency, bandwidth capacity upgrade, and furthermore the presence of basic frequency with zero phase velocity. In this paper, we discuss about a Microstrip Patch antenna which is based on composite right/left-hand transmission line.  Â

Time-domain analysis of a CRLH coupled-line coupler using the CN-FDTD method

In this study, the implicit Crank–Nicolson finite-difference time-domain (CN-FDTD) method is applied to discretize the governing telegrapher's equations of a composite right-/left-handed (CRLH) coupled-line coupler. The unconditionally stable CN-FDTD is compared with the conventional leap-frog (LF) FDTD method. The results obtained from the CN-FDTD scheme show up to 10 times increase in the temporal step size, reflecting in a dramatic decrease in processing time; in addition to having a good agreement with the LF method and the measurements.

Fast method for analysing nonlinear composite right/left‐handed transmission lines based on finite‐difference time‐domain method

In this study, a new finite-difference time-domain (FDTD) scheme is presented for analysing nonlinear composite right/left-handed (CRLH) transmission lines, with reduction of the central processing unit time. A step by step analysis is demonstrated to solve the equations for nonlinear CRLH transmission lines based on the FDTD method. The proposed method is applied to a nonlinear CRLH transmission line as an example and the results are confirmed by those of the conventional FDTD method. The comparisons reveal that the presented solution efficiently decreases by about 82% of the computational time consumption.

A compact ultra wide band bandpass filter with dual band notch designed based on composite right/left‐handed transmission line unit cell

In this article, we propose an ultra wide band (UWB) bandpass filter with dual notch characteristics. The proposed filter is designed based on composite right/left handed (CRLH) transmission lines. The filter is having a compact size of 2.4 mm × 8.78 mm and printed on FR4 material with relative permittivity 4.4 with thickness 1.6 mm. The filter is constructed by series of strip lines, which forms interdigital capacitance and shunt inductors allowing both low and high frequencies of the UWB to pass. The selectivity in lower and higher parts of the UWB is achieved by the slots etched from the ground plane. The dual band notch is obtained at 4 GHz and 7 GHz using the L-shaped strip lines on both sides of the filter. The comparative analysis of the proposed UWB band pass filter without and with notch characteristics is presented with the help of the S11 and S21 curves.

Dual‐band beam scanning filtering antenna using dual‐eighth mode substrate integrated waveguide‐based metamaterial structure

In this article, a dual-band beam scanning antenna with filtering capability is proposed by using novel dual-eighth mode substrate integrated waveguide-based dual-band metamaterial (DB-MTM) structure. The novel DB-MTM structure consists of two interconnected modified eighth mode substrate integrated waveguide (EMSIW) structures, which is designed by etching four interdigital fingers on the upper ground, and has two balanced composite right/left-handed (CRLH) passbands. Taking advantage of the continuous phase constant changing from negative to positive values within the two CRLH passbands of the DB-MTM structure, a beam scanning antenna, which is composed of 11 dB-MTM unit cells, is designed to achieve continuous beam scanning from backward to forward directions within dual operating frequency bands. For verification, the proposed dual-band antenna is fabricated and measured. According to the measurements, the fabricated antenna can scan its main beam from −72° to +57° and −70° to +38° over the two operating frequency bands of 3.40-4.95 GHz and 5.85-6.80 GHz, respectively; and exhibits very sharp transitions at the band edges over the two operating frequency bands. Besides, the measured peak gains in the two operating bands are 14.0 dB at 4.5 GHz and 14.5 dB at 6.4 GHz. Moreover, the measurements show good agreement with the simulations, proving the validity of the design method, and further expanding the applications of EMSIW.

High gain dual-band distributed amplifier using new composite right/left-handed transmission line

AbstractIn this paper, a high-gain dual-band distributed amplifier (DBDA) based on the metamaterial transmission line (TL) is proposed. To have two separate frequency bands in the distributed amplifiers, the composite right/left-handed (CRLH) TLs are used instead of conventional TLs. Although both forward and reverse gains of the distributed amplifiers are available in this case, they suffer from their low gains. In this paper, to increase the DBDA power gain, a new circuit architecture for the CRLH TL is introduced. By using the proposed CRLH TL, a lower wave attenuation coefficient at the forward band of the DBDA is achieved than the conventional structures, which causes a higher forward power gain. Simulation results also show that the power gain of the proposed DBDA is about 28.5 dB at the desired frequency bands, and good agreement between the measurement and simulation results confirms the accuracy of the design method.

A compact dual-band bandpass SIW filter using uniplanar combination of the CRLH and resonant type metamaterials

ABSTRACTA new manner of obtaining dual bandpass behaviour in substrate-integrated waveguide (SIW) using a uniplanar combination of composite right/left-handed (CRLH) transmission line and complimentary double split single ring resonator (CDSSRR) is presented and analysed in this paper. The proposed dual band structure has the advantage of miniaturisation due to the presence of both the passbands below the characteristic cutoff frequency of the SIW.A high passband transmission zero overcomes the poor frequency selectivity, and the two resonant frequencies are independently controllable. There are very low insertion losses in both passbands as compared to DGS structures and fabrication simplicity is ensured due to an intact ground. The potential for application of the proposed structure to the design of completely planar miniaturised dual band bandpass metamaterial filters has been verified by fabricating a two-stage filter based on the proposed combination. The measured results are in good agreement with the simulation results.

A Novel Metamaterial Transmission Line With Adjustable Left-Handed Elements and Its Application to <inline-formula> <tex-math notation="LaTeX">$H$ </tex-math> </inline-formula>-Plane Filter

This letter presents a metamaterial transmission line (TL) with enhanced designing flexibility. Interdigital fingers and rectangular slots are etched on the top and bottom metal plates to generate series capacitances and shunt inductances, respectively, which give rise to the composite right-/left-handed (CRLH) property. In this structure, the rectangular slots provide adjustable shunt inductances that facilitate the design of CRLH property compared with that in previous work. Furthermore, the increment of the shunt inductances also enables more compact size due to lower resonance. Examples are given to verify the advantages by comparing the dispersions, S-parameters, and extracted values of lumped elements for two types of CRLH TLs with various physical dimensions. In addition, a bandpass filter is implemented by the proposed CRLH TL with partial H-plane coupling structure. The filter is fabricated and measured, and the result shows a good agreement between the measurement and simulation.

Self-Oscillating Active Integrated Antenna With Harmonic Suppression Using Metamaterial Resonators and Ground Radiation

A self-oscillating active integrated antenna (AIA) with harmonic suppression using metamaterial resonators and ground radiation is proposed and investigated. Two composite right-/left-handed (CRLH) cells are connected in parallel and operated at negative first-order mode as the left-handed resonators to serve as the frequency selective element and the feedback path of the oscillating circuit at the same time. Meanwhile, the radiation parameters are independently controlled by exciting dipole-like ground-mode radiation using the CRLH cells. Benefiting from the high-quality factor of the CRLH cells and the newly added harmonic choking filters, the proposed AIA shows extraordinarily low phase noise, along with notable radiation parameters and good dc-to-RF conversion efficiency. The design principle, linear and nonlinear simulated data, and experimental results are carefully discussed and validated.

A Compact CRLH Circularly Polarized Leaky-Wave Antenna Based on Substrate-Integrated Waveguide

A compact single-radiator circularly polarized (CP) leaky-wave antenna (LWA) based on composite right/left-handed (CRLH) transmission line is presented. The proposed antenna is based on substrate-integrated waveguide (SIW), and its unit cell consists of a T-shaped interdigital slot, which provides a CRLH property, a proper CP, and also effective compactness for the full-length LWA. The proposed LWA provides beam scanning from −19° to +84° over the frequency range of 7.35–10.15 GHz, while maintaining a good CP. By providing the balanced condition for the CRLH unit cell, a continuous backward-to-forward scanning including broadside is achieved. The maximum gain of the LWA is 8.95 dB which is satisfactory, considering the compactness of the antenna. Moreover, the radiation efficiency has an average of 85.7% over the operating frequency band. The measurement results are in good agreement with the simulation ones and show considerable advantages over the SIW-based CP LWAs proposed in the recent literature.

Multi-functional RF coils for ultra-high field MRI based on 1D/2D electromagnetic metamaterials

Electromagnetic metamaterials have already proven very valuable for the enhancement and molding of RF magnetic fields within ultra-high field MRI scanners at 7T. We report on our development of coil elements based on composite right-/left-handed (CRLH) 1D electromagnetic (EM) metamaterial transmission lines (metalines) operating in the zeroth order resonance (ZOR) to foster uniform RF magnetic field distributions along the scanner axis. Tailored EM metalines supporting full-wave or quarter-wave resonances are used either as metamaterial ring antenna or as dual-band coil elements for simultaneous 1H/23Na imaging. The EM metalines are key to the MetaBore, which is a fully adaptive RF field control scheme based on a periodic axial arrangement of conformal metamaterial ring antennas in the framework of high-field traveling-wave MRI. With the 2D EM metamaterials (metasurfaces) we realized high-impedance surfaces (HIS) in order to enhance the uniformity and directivity of the RF magnetic field from e.g. overlaid (elongated) dipole elements towards the probe volume. The designs include simulation studies of the overall multichannel coil systems, which are carried out with our home-made, open source electromagnetic 3D EC-FDTD solver openEMS supporting conformal cylindrical inhomogeneous meshing. Experimental verifications of our coils have been carried out within 7T MRI scanners (Siemens Magnetom).

Dual-Band and Polarization-Flexible CRLH Substrate-Integrated Waveguide Resonant Antenna

A dual-band and polarization-flexible substrate-integrated waveguide (SIW) resonant antenna based on composite right-/left-handed (CRLH) structure is presented in this letter. The proposed antenna consists of a CRLH SIW resonator and dual feeding lines. A slot and surface-mount technology capacitors on the top metallic layer of SIW resonator provide necessary reactance to realize multiresonance CRLH structure. Due to the intrinsic multiband characteristic of a CRLH structure, the proposed antenna can provide dual-band broadside radiations. Polarization flexibility is realized by two orthogonal feedlines. Utilizing the CRLH resonator instead of the conventional square resonator, such as patch antenna, allows antenna miniaturization. The electrical lengths of the sidewalls for the proposed square SIW resonant antenna are 75% (for first resonant mode) and 44% (for second resonant mode) shorter than that of the previously proposed dual-band polarization-flexible SIW antenna. To highlight the unique advantages, the dual-band circularly polarized antenna array based on the proposed antenna element is presented. Dual-band circularly polarized radiation is supported by the dual-band CRLH transmission-line-based feeding network.