Composite Right- And Left-handed Research Articles

A Dual-Mode Power Divider With Embedded Meta-Materials and Additional Grounded Resistors

This article presents a dual-mode power divider (PD) that offers new working mechanism, compact size, significant design freedom, wide working bandwidth, arbitrary power division, and ultrawide isolation between the two output ports. The structure is simple in comparison with conventional Wilkinson PDs in that only two composite right-and left-handed (CRLH) transmission lines (TLs) grounded through two resistors are used. Different from previous CRLH-TL-embedded studies in that almost all CRLH-TLs operate at quarter-wavelength phase responses, in the present work, the zero-degree property is noted and used to modify the impedance variation curves. Additionally, because of the use of grounded resistors, the proposed PD can operate in two modes, such that when high-value resistors are used, the PD operates in a lossless mode, while when low-value resistors are used, the PD operates in an attenuated mode. Because working power has been significantly improved due to progress in modern RF system development, more attenuation elements are required. This means that attenuated PDs will become very useful in the future. For verification, two PDs operating in different working modes and power divisions are designed and fabricated. Based on the experimental results, both PDs demonstrate good performance over more than 60% of the bandwidth with reference to the 15-dB S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> , ultrawide isolation, full port matching, and compact size.

Differential‐to‐single‐ended crossover based on dumbbell‐shaped defected ground resonators for dual‐band applications

This article presents a novel differential-to-single-ended (DS) crossover by using two rings included of controllable frequency ratio of composite right- and left-handed (CRLH) transmission lines for dual-band applications. To reject the out-of-band differential-mode transmission coefficient, two dumbbell-shaped defected ground resonators (DGRs) are utilized over the differential transmission lines. Theoretical analysis proves that the frequency ratio can be controlled by choosing the number of designing CRLH cells and the parameter values appropriately. Also, desired electrical lengths and impedances of DGRs were obtained at the bandstop notch of differential-mode transmission coefficient by conducting common- and differential-mode analysis of lumped element equivalent circuit. To validate the proposed structure, two fabricated prototypes including the DS crossover designing at 1.8 and 4.2 GHz and separate differential lines with embedded DGRs were fabricated and measured. Measurement mixed-mode results exhibit that the fabricated crossover has great results at both frequency bands and has a good out-of-band differential insertion loss rejection.

A Fully-Printed CRLH Dual-Band Dipole Antenna Fed by a Compact CRLH Dual-Band Balun.

In this paper, a new design method is proposed for a planar and compact dual-band dipole antenna. The dipole antenna has arms as a hybrid CRLH (Composite right- and left-handed) transmission-line comprising distributed and lumped elements for the dual-band function. The two arms are fed by the outputs of a compact and printed CRLH dual-band balun which consists of a CRLH hybrid coupler and an additional CRLH phase-shifter. Its operational frequencies are 2.4 and 5.2 GHz as popular mobile applications. Verifying the method, the circuit approach, EM (Electromagnetics) simulation and measurement are conducted and their results turn out to agree well with each other. Additionally, the CRLH property is shown with the dispersion diagram and the effective size-reduction is mentioned.

Design method of new power divider employing zero-degree transmission line with arbitrary power dividing ratio

In this paper, a new structure of power divider (PD) employing zero-degree transmission line (TL) with arbitrary power dividing ratio is firstly proposed. Detailed analysis is performed according to the modified even- and odd-mode analytical method. This procedure shows that the resistor between the two output ports corresponds to the wide isolation band, while the other two grounded resistors can not only realize the two output ports matching, but also provide better power handling capability in comparison with the conventional Wilkinson PD. Specifically, a zero-degree composite right- and left-handed (CRLH) transmission line (TL) is used in the PD structure, which results in a smaller size, higher design flexibility, and wider operating band than the conventional Gysel PD with the reference of 10-dB return loss and 1-dB insertion loss. Closed-form design equations are derived, and the proposed design theory is verified by two PDs with the same centre frequency but different power dividing ratio (P2/P1) as 1:1 and 2:1, respectively. According to the experiment results, both PDs have a better out-of-band rejection than the conventional Wilkinson PD, more than 100% fractional operating bandwidth under full port matching, and more than 85% isolation bandwidth with the reference of 15-dB S32.

Dual‐band balanced‐to‐single‐ended crossover based on composite right‐ and left‐handed transmission lines

This Letter presents a balanced-to-single-ended (BS) crossover for dual-band applications by using two rings included of composite right- and left-handed (CRLH) transmission lines (TLs) with controllable frequency ratio feature. Two dumbbell defected ground structures (DGSs) are employed through balanced TLs to suppress out-of-band common-mode. Theoretical analysis expresses that the frequency ratio can be controlled by suitable selecting of the element values and the number of designing cells of the CRLH TLs. Furthermore, desired impedances and electrical lengths of DGSs are obtained at the frequency of common-mode rejection by using even- and odd-mode analyses. To validate the proposed structure, a dual-band BS crossover operating at 1.8 and 4.2 GHz is fabricated. Measurement results show that the fabricated proposed structure has good performance at the designed frequency bands.

Linear array arrangement using composite right‐/left‐handed transmission lines for magnetic resonance imaging

AbstractArray coils for magnetic resonance imaging have been used to improve field uniformity, improve signal‐to‐noise ratios, and increase imaging speed. Alternative radio frequency (RF) coils that use metamaterials, such as loop or microstrip coils, have recently been proposed and are expected to provide better performance than the traditional RF array coils. Transmission lines (TLs) based on metamaterials are known as composite right‐ and left‐handed (CRLH) TLs, which are artificially created by adding inductances and capacitances to a common TL. CRLH TLs have a zero‐order resonance mode, wherein wave propagation is independent of the TL's electrical length. Decoupling between array elements is important for obtaining the benefits of parallel imaging. In this study, we analyze the decoupling properties between two CRLH TLs. In addition, we design a linear array of four CRLH TLs to obtain a uniform magnetic (|B1|)‐field in the axial‐ and longitudinal‐direction at 7T for the corresponding frequency of 300 MHz.

Dual‐band planar antenna loaded with CRLH unit cell for WLAN/WiMAX application

A dual-band planar antenna based on composite right and left handed (CRLH) metamaterial is presented. The proposed antenna is comprised of a host folded planar monopole antenna and a CRLH transmission line unit cell. Due to another resonance frequency generated from the loaded CRLH unit cell, the presented antenna is actually a planar antenna with dual resonance bands at the centre frequency of 2.50 and 5.80 GHz, respectively, which can be regulated independently. The developed antenna also has different polarisations, the linear polarisation at the lower band and the circular polarisation at the upper resonance band. Rather than the complicated structure as before, this antenna is fabricated easily for the simple configuration without holes and the interdigital capacitances. The results of this study show that the reflection coefficient and radiation pattern have a good agreement between the simulation and measurement, the simulated relative bandwidth is 22.8% (2.22–2.79 GHz) and 10.8% (5.42–6.04 GHz), which meet the Wi-Fi/Worldwide Interoperability for Microwave Access (WiMAX) specification very well.

Quad‐element multi‐band antenna array in the smart mobile phone for LTE MIMO operations

ABSTRACTIn this paper, a quad‐element MIMO antenna array in the smart phone has been developed for multi‐wideband operations covering 750–960 MHz and 1700–3600 MHz. The proposed antenna element consists of two parts: one is a dielectric resonator that operates in a TE11δ mode and generates the antenna's upper band, and the other is a radiating patch with a meander line connected to the ground plane, which achieves composite right‐ and left‐handed (CRLH) metamaterial transmission lines structure and contributes the antenna's lower band. Each of four antenna elements fitting in a small region of 25 × 16 × 4 mm3 are located on a circuit board of 125 × 75 × 0.8 mm3. The slots are etched on the metallic ground plane to guarantee good isolation between four antenna elements. The MIMO antenna array is fabricated, and the simulated and measured results show good performance in terms of S parameters, radiation pattern, total efficiency, and envelope correlation coefficient (ECC). © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2619–2626, 2016

Ultrasmall Dual-Band Metamaterial Antennas Based on Asymmetrical Hybrid Resonators

A new type of hybrid resonant circuit model is investigated theoretically and experimentally. The resonant model consists of a right hand (RH) patch part and a composite right and left handed (CRLH) part (RH + CRLH), which determines a compact size and also a convenient frequency modulation characteristic for the proposed antennas. For experimental demonstration, two antennas are fabricated. The former dual-band antenna operating at f-1=3.5 GHz (Wimax) and f+1=5.25 GHz (WLAN) occupies an area of 0.21λ0×0.08λ0, and two dipolar radiation patterns are obtained with comparable gains of about 6.1 and 6.2 dB, respectively. The latter antenna advances in many aspects such as an ultrasmall size of only 0.16λ0×0.08λ0, versatile radiation patterns with a monopolar pattern at f0=2.4 GHz (Bluetooth), and a dipole one at f+1=3.5 GHz (Wimax) and also comparable antenna gains. Circuit parameters are extracted and researched. Excellent performances of the antennas based on hybrid resonators predict promising applications in multifunction wireless communication systems.

An Octave Bandwidth Metamaterials-based Hexagonal Patch Antenna

A broadband metamaterials (MTM)-based hexagonal patch antenna is designed and presented. A hexagonal shape of a top patch on a mushroom structure makes not only direct-current paths between two ends of the patch but also round-current path along the outside of the patch, thereby widening a resonance frequency of the mushroom MTM antenna. Moreover, input microstrip transmission line acted as a reflecting element for the surface wave, resulting in forward-directed end-fired radiation. The hexagonal patch was implemented by utilizing a composite right-and left-handed (CRLH) transmission line. The antenna operates from 15.9 GHz to 30.6 GHz covering the Ku- to Ka-band. The antenna gain is from 6 dBi to 9.3 dBi with small size compared to the conventional antennas. The application areas are in automotive radars and ground penetrating radar (GPR). DOI: http://dx.doi.org/10.5755/j01.eee.21.5.13325

An Octave Bandwidth Metamaterials-based Hexagonal Patch Antenna

A broadband metamaterials (MTM)-based hexagonal patch antenna is designed and presented. A hexagonal shape of a top patch on a mushroom structure makes not only direct-current paths between two ends of the patch but also round-current path along the outside of the patch, thereby widening a resonance frequency of the mushroom MTM antenna. Moreover, input microstrip transmission line acted as a reflecting element for the surface wave, resulting in forward-directed end-fired radiation. The hexagonal patch was implemented by utilizing a composite right-and left-handed (CRLH) transmission line. The antenna operates from 15.9 GHz to 30.6 GHz covering the Ku- to Ka-band. The antenna gain is from 6 dBi to 9.3 dBi with small size compared to the conventional antennas. The application areas are in automotive radars and ground penetrating radar (GPR). DOI: http://dx.doi.org/10.5755/j01.eee.21.5.13325

基于零阶谐振超材料的新型LTE智能手机天线设计

With the rapid development of next-generation wireless communication systems, a novel smart mobile phone antenna covering Long-Term Evolution (LTE) bands is proposed based on the theory of composite rightand left-handed (CRLH) transmission lines, which can be used to design a miniaturized and multi-band antenna. In this paper, the theory of zeroth-order resonance (ZOR) is particularly recommended for antenna design to produce the equivalent left-handed capacitor and left-handed inductor. In the meantime, the ground current is also used to achieve miniaturization. The proposed ZOR metamaterial antenna can cover LTE747/GSM850/900 and DCS1800/PCS1900/UTMS/LTE2300/2600; further, it provides the performance benefits of an effective radiation pattern, as well as high gain and high efficiency, which can meet the requirements of a LTE smart mobile phone. The performance impact of the proposed antennas operating characteristics is also analyzed. The measured results of the fabricated antenna are in good agreement with the simulated antenna. They confirm that the fabricated ZOR metamaterial antenna offers the advantages of miniaturization and good performance.

Band pass filter bank design (250–500 MHz) for radio astronomy application based on metamaterial ZOR techniques

Metamaterial (MTM) is an artificial composite material for which we can change its electromagnetic properties [1]. The equivalent circuit approach of MTM was developed by Caloz and Itoh [2] and Sanada et al. [3], and this approach has led to the concept of composite right- and left-handed (CRLH) materials. This concept fully takes into account the parasitic right-handed (RH) effects, which is unavoidable in a practical application. The zeroth-order resonator (ZOR) has the mode number zero, and its resonator length is invariant of its wavelength. Sanada et al. [3] first proposed MTM-ZOR and realized it in microstrip configuration. Using the MTM-ZOR technique, several researchers [4]–[8] have designed band pass filters (BPFs) in different frequency bands.

An Orthogonally Polarized Negative Resonance CRLH Patch Antenna

A novel fully-printed microstrip antenna with negative first resonance and dual polarization is proposed. The radiator is printed on the 1-layer substrate instead of multilayers. The -1st resonance results from a composite right- and left-handed(CRLH) structure that has a circumferentially interlocked gap capacitively coupling a patch with a shorted-ring. This compact antenna is provided with a dual-polarization capability by creating two orthogonal linear polarizations in one body with coaxial feeds. The design is carried out by doing full-wave EM field simulation which is compared with the measurement of the fabricated antenna prototype. The measured results give the gain of 5 dBi and the efficiency of 78% at the -1st resonance mode as the center frequency of a downlink channel of the bandwidth over 20 MHz with 29 dB polarization isolation for mobile communication.

LTE smartphone antenna design based on zeroth-order resonant metamaterials

With the rapid development of next-generation wireless communication systems, a novel smart mobile phone antenna covering Long-Term Evolution (LTE) bands is proposed based on the theory of composite rightand left-handed (CRLH) transmission lines, which can be used to design a miniaturized and multi-band antenna. In this paper, the theory of zeroth-order resonance (ZOR) is particularly recommended for antenna design to produce the equivalent left-handed capacitor and left-handed inductor. In the meantime, the ground current is also used to achieve miniaturization. The proposed ZOR metamaterial antenna can cover LTE747/GSM850/900 and DCS1800/PCS1900/UTMS/LTE2300/2600; further, it provides the performance benefits of an effective radiation pattern, as well as high gain and high efficiency, which can meet the requirements of a LTE smart mobile phone. The performance impact of the proposed antennas operating characteristics is also analyzed. The measured results of the fabricated antenna are in good agreement with the simulated antenna. They confirm that the fabricated ZOR metamaterial antenna offers the advantages of miniaturization and good performance.

Design of a broadband hexagonal-shaped zeroth-order resonance antenna with metamaterials

A broadband hexagonal-shaped metamaterials (MTMs)-based zeroth-order resonant (ZOR) antenna was designed and fabricated. The hexagonal shape of a top patch on a mushroom structure makes not only direct-current paths between the two ends of the patch but also round-current paths along the outside of the patch, thereby widening the resonance frequency of the mushroom MTM antenna. According to the shape of the hexagon patch, the presented antenna achieved impedance bandwidth of 58.6% corresponding to ultra-wideband technology. The proposed ZOR antenna was modeled by utilizing a composite right- and left-handed (CRLH) transmission line and provided 4 to 9.3 dBi of the antenna gain with reduced size as compared to conventional microstrip antennas at Ku- to K-band frequencies.

Compact Dual-Band Three-Way Metamaterial Power-Divider with a Hybrid CRLH Phase-Shift Line

A compact dual-band three-way metamaterial power divider is proposed that has three in-phase outputs. Fully printed composite rightand left-handed (CRLH) unequal and equal power dividers are first implemented for 900-MHz and 2.4-GHz bands with the power-division ratios of 2:1 and 1:1, respectively. An initial 1:1:1 power divider is then achieved by incorporating the input of the two-way equal block into an output of the unequal block, and trimming the interconnection parameters. The condition of an identical phase at the three outputs of the power divider is then met by devising a hybrid CRLH phase-shift line to compensate for the different phase errors at the two frequencies. This scheme is confirmed by predicting the performance of the power divider with circuit analysis and full-wave simulation and measuring the fabricated prototype. They results show agreement; the in-phase outputs as well as the desirable power-division are accomplished and outdo the conventional techniques.

Metamaterial CRLH Structure-based Balun for Common-Mode Current Indicator

We proposed a new PCB-type 'common-mode current(<TEX>$I_c$</TEX>) and differential-mode current(<TEX>$I_d$</TEX>) detector' working for fast detection of <TEX>$I_c$</TEX> and <TEX>$I_d$</TEX> from the differential-mode signaling, with miniaturization effect and possibility of cheaper fabrication. In order to realize this device, we suggest a branch-line-coupler balun having a composite right- and left-handed(CRLH) one-layer microstrip phase-shifting line as compact as roughly <TEX>${\lambda}_g/14$</TEX>. The presented balun obviously is different from the conventional bent-&-folded delay lines or slits on the ground for coupling the lines on the top and bottom dielectrics. As we connect the suggested balun output ports of the differential-mode signal lines via the through-port named U and coupled-port named L, <TEX>$I_c$</TEX> and <TEX>$I_d$</TEX> will appear at port <TEX>${\Delta}$</TEX> and port <TEX>${\Sigma}$</TEX> of the present device, in order. The validity of the design scheme is verified by the circuit-and numerical electromagnetic analyses, and the dispersion curve proving the metamaterial characteristics of the geometry. Besides, the examples of the <TEX>$I_c$</TEX> and <TEX>$I_d$</TEX> indicator are observed as the even and odd modes in differential-mode signal feeding. Also, the proposed device is shown to be very compact, compared with the conventional structure.

L대역 군위성 중계기 경량화를 위한 메타재질기반 소형 이중대역 3분기 전력분배기의 설계

This paper proposes a compact dual-band 3-way power divider that helps lowering the weight of a transceiver for the L-band or multi-purpose satellite communication. Instead of the multi stages or tapering which ends up with loss accumulation and size-growth, the non-linear dispersive phases from the metamaterial CRLH(composite right and left-handed) properties are obtained by the accurate formulation and implemented by the short transmission line segments. Firstly, the CRLH dual-band two-way unequal power divider and equal power divider are separately designed. And then, the input of the two-way equal power divider is plugged in the output port of the unequal one, and the entire geometry is slightly adjusted for the desirable performance. The circuit analysis and full-wave simulation are used to predict the frequency responses and validated by the measurement of the prototype. Besides, the size-reduction effect is addressed.

Fully Printed Dual-Band Power Divider Miniaturized by CRLH Phase-Shift Lines

In this letter, a compact and fully printed composite right- and left-handed (CRLH) dual-band power divider is proposed. The branches of the conventional Wilkinson power divider are replaced by subwavelength CRLH phase-shift lines having +90° for one frequency and −90° for another frequency for dual-band and miniaturization performance. Equations are derived for the even- and odd-mode analysis combined with the dual-band CRLH circuit. A PCS and a WLAN band are chosen as the test case and the circuit approach agrees with the CAD simulation and the measurement. Additionally, the CRLH property is shown with the dispersion diagram and the eightfold size reduction is noted.