Composite Right- And Left-handed Transmission-line Research Articles

A triple‐band dual‐polarized CRLH antenna for wireless applications

AbstractThis paper presents an asymmetric coplanar waveguide fed triple‐band (1.99, 4.06, and 5.23 GHz) dual polarized antenna based on composite right‐ and left‐handed transmission line (CRLH‐TL) approach. The two lower bands of the antenna are linearly polarized whereas the rest is circularly polarized (CP). 20.49% 3 dB axial ratio bandwidth is achieved for the CP band which is higher than the recently reported triple band CRLH‐TL antennas. It has a compact size of 0.085 × 0.097 × 0.01λ0, where λ0 is the free space wavelength at ZOR frequency (1.99 GHz). The antenna is suitable for UMTS/WCDMA/PCS, WiMAX, and WLAN/Wi‐Fi applications.

Circularly polarized ACPW Fed CRLH-TL based ZOR antenna with band notch characteristics

AbstractIn this paper, two asymmetric co-planar waveguide (ACPW) fed circularly polarized (CP) zeroth-order resonance (ZOR) antennas (Antenna I and II) are presented using a composite right and left-handed transmission line (CRLH-TL) approach. By adding a stub on the left side of the ACPW ground and adjusting its length, circularly polarization property has been achieved in Antenna I. The simulated 3 dB axial ratio bandwidth (ARBW) of Antenna I is 1750 MHz (3.50–5.25 GHz). Next, the left side ground plane of Antenna I is further defected by etching a quarter wavelength slit to introduce a notch band (Antenna II). Antenna II has an extended 10 dB return loss bandwidth of 2200 MHz (3.28–5.48 GHz) with a band notch from 4.18–4.65 GHz that isolates the WiMAX and 5.2 GHz WLAN bands. ARBWs of 1080 and 870 MHz are achieved in the first and second band of Antenna II. The overlapping 3 dB ARBW and 10 dB return loss bandwidths of Antenna II in these two bands are 770 and 830 MHz, respectively.

A CPW‐fed band notched wideband circularly polarized ZOR antenna based on CRLH‐TL approach

This article presents design and analysis of three wide band zeroth-order resonance antennas (antennas I, II, and III) using composite right and left-handed transmission line (CRLH-TL) approach. Coplanar waveguide technology, single layer via-less structures are used to have the design flexibility. The bandwidth characteristics are analyzed by using lumped parameters of CRLH-TL. By introducing a simple slot in the ground plane of antenna I both bandwidth enhancement and circularly polarization characteristics are achieved in antenna II. Another quarter wave L-shaped slot has been introduced in the ground plane of antenna II to introduce a notch band in the frequency response of antenna III. Achieved measured 10 dB return loss bandwidth of antenna I and antenna II are 960 (3.3-4.26 GHz) and 2890 MHz (2.77-5.66 GHz), respectively. Antenna III offers measured 10 dB return loss bandwidth of 3220 MHz (2.32-5.54 GHz) with a band notch from 2.39 to 2.99 GHz that isolates the 2.4 GHz WLAN and 3.5 GHz WiMAX band. Antenna II and antenna III have circular polarization property with measured axial ratio bandwidth of 440 MHz. The measured peak realized gain of antennas II and III is around 1.53-2.9 dBi.

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.

Miniaturized Dual Bandstop Filter using CRLH Transmission Line

Design of a dual wide bandstop filter is proposed based on Composite Right and Left-Handed Transmission-line (CRLHTL) . Two stop bands with center frequencies of 8.3 GHz and 12.9 GHz are achieved with fractional bandwidths 57.8% and 32.5% respectively. Spiral interdigital capacitors and stub inductors are employed to designed filter. The proposed bandstop filter provides low passband insertion loss, better attenuation in stopbands, and low cost. The total filter size is about 7.8mm×15.1mm which is very compact compared to other metamaterial and conventional microstrip filters. Filter is also fabricated and measured to demonstrate the performance matched with simulation results.

Optimal Design of a Compact Filter for UWB Applications Using an Improved Particle Swarm Optimization

This paper proposes an improved particle swarm optimization (PSO) process to design a high-performance compact ultrawideband (UWB) filter. The filter consists of one-cell composite right- and left-handed-transmission line (CRLH-TL) resonator, a stepped impedance (SI), and two spurlines. The one-cell CRLH-TL resonator has compact size but performs wide passband filtering. One SI and two spurlines are employed to reject both the harmonics outside the UWB and the wireless local area network (WLAN) (5.15–5.825 GHz) band. The improved PSO consists of the conventional PSO with the sensitivity analysis, and the process for checking the ripple. The improved PSO suppresses the ripple and accelerates the optimization. During the improved PSO, the objective function converges from the 116th iteration. In addition, the characteristic of the filter is optimized to get acceptable results. The proposed filter has the overall size of $14 \times 15$ mm2 ( $0.63\lambda _{g} \times 0.53\lambda _{g})$ only, a 105% bandwidth for a return loss >10 dB, a flat insertion loss $11.5\sim 22$ GHz and WLAN band. In particular, the ripple in the passband is minimized significantly by the improved PSO.

GA-Optimized Compact Broadband CRLH Band-Pass Filter Using Stub-Inserted Interdigital Coupled Lines

The design of a new compact band-pass filter is proposed, which is based on the microstrip composite right- and left-handed transmission-line (CRLH-TL) structure. Particularly, the interdigital coupled (IDC) lines of the CRLH geometry are proposed to be parted by inserting open stubs to meet the specifications on the passband. In addition, there is another pair of stubs to complete the design in a limited space. These are considered in the TL-based analysis and the design parameters are calculated by genetic algorithm optimization. The measurement is shown to be acceptable and agreeable with the circuit and electromagnetic field simulations. In addition, the zerothorder resonance (ZOR) phenomenon is verified.

Reducing the Interference in Compact MIMO Antennas of CRLH-TL-Based Broadside-Capacitive and Slot Couplings

In this paper, the interference in small MIMO antennas having two identical composite right- and left-handed transmission-line(CRLH-TL)-based radiating elements is remarkably decreased. The radiating element has the broadside-capacitive coupling as well as slots to be equivalent to the CRLH-TL to prevent the size from increasing for an LTE high band. The suspended line bridging the two radiating elements is optimized to lower the interference between them down to -23 dB, while the overall MIMO antenna system is compact and its antenna performance is acceptable. The design is tested for 2.5 GHz.

Compact multiband antenna with CRLH‐TL ZOR for wireless USB dongle applications

AbstractA compact multiband antenna with composite right‐ and left‐handed transmission line (CRLH‐TL) zeroth‐order resonator for wireless universal serial bus dongle applications is proposed in this article. The proposed antenna occupying a small volume of 12 × 28 × 5.8 mm3 comprises a folded monopole which can generate two resonant modes to cover the GSM850/900 (820–960 MHz) and the LTE2500 operation (2500–2690 MHz) and a CRLH‐TL ZOR structure which is capacitively excited by the folded monopole to generate zeroth‐order resonant mode to cover LTE700 (746–787 MHz). The proposed antenna offers nearly omnidirectional radiation patterns, the measured peak gain are obtained from 0.8 to 3.4 dBi, and measured antenna efficiency varies from about 40–56% in the whole operation band. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1133–1138, 2014

Soliton decay in composite right- and left-handed transmission lines periodically loaded with Schottky varactors

Soliton decay in a composite rightand left-handed transmission line periodically loaded with Schottky varactors, termed a Schottky CRLH line, is characterized to obtain broadband envelope pulses. When the three waves in the line satisfy the wave-number and frequency resonance conditions, they are governed by the three-wave resonant interaction equation, which have solutions that exhibit soliton decay, i.e., the decay of the highest frequency envelope into those carried by the other two frequency solitons. Due to the left-handedness, solitons resulting from the decay can have much smaller width than the incident envelope. This paper discusses the potential of a Schottky CRLH line as a generator of broadband envelope pulses.

Tunable Bandpass Filter with Varactors Based on the CRLH-TL Metamaterial Structure

This paper presents a tunable bandpass filter based on the varactor-loaded composite right- and left-handed transmission line (CRLH-TL). The proposed filter is composed of one CRLH-TL unit cell, which corresponds to the third-order bandpass filter. The tunable bandpass filter is designed using only lumped-elements. The use of lumped elements saves space and lowers the fabrication cost. The size of the proposed tunable bandpass filter is 17 mm × 5 mm, neglecting the feed lines and DC lines. All of the varactors are controlled by one DC bias. The center frequency of the bandpass filter can be controlled by varying the value of the varactors. The tunable range of the center frequency is from 412.5 to 670 MHz. The insertion loss is less than 3 dB, the return loss is more than 10 dB in the passband.

Dual-Band N-Way Series Power Divider Using CRLH-TL Metamaterials With Application in Feeding Dual-Band Linear Broadside Array Antenna With Reduced Beam Squinting

A general design for a non-radiating dual-band N-way series power divider (SPD) is presented in this paper. The non-linear phase responses of composite right and left handed transmission-line (CRLH-TL) and non-radiating CRLH-TL (NR-CRLH-TL) are used to achieve the desired dual-band performance. Theory and design procedure of this divider are analyzed in detail. For demonstration, a dual-band 3-way power divider was designed, fabricated and tested at two arbitrary design frequencies: 0.915 GH (UHF) and 2.440 GHz (ISM). There is nearly equal and in-phase power division to all three output ports in the two passbands while the measured input return loss remains below 10 dB. Also, the dual-band divider presents the benefit of setting the output ports arbitrarily apart. In addition, the dual-band nature of the proposed SPD, low cost and easy integration with printed antenna make it well suited for feeding dual-band planar antenna arrays. To verify the performance of the proposed divider, the designed dual-band 3-way SPD is used as a series feed network for a linear array of printed monopole antennas, designed to radiate in the broadside direction. It is shown that the proposed dual-band planar antenna array experiences a decrease in the amount of beam squinting with a change in frequency for both the operating bands.

Frequency reconfigurable zeroth‐order resonant antenna using RF MEMS switch

AbstractIn this article, a frequency reconfigurable zeroth‐order resonant (ZOR) antenna using RF micro‐electron‐mechanical‐system (MEMS) switch has been implemented. The ZOR characteristics of the proposed antenna are realized using the composite right‐ and left‐handed (CRLH) transmission line, which is realized by way of a rectangular slot on the ground plane of mushroom‐structured antenna to minimize the antenna size. In addition, the RF MEMS switches are introduced on the slotted ground plane to change operation frequency. Depending on the states of the RF MEMS switch on the slotted ground plane, a shunt inductance of the CRLH transmission line is changed, and its resonant frequency becomes tunable. From the experimental results, the resonant frequency of the proposed antenna is changed from 4.95 to 4.66 GHz. Additionally, the proposed antenna's size is reduced by 71.5% compared with the conventional half‐wavelength patch antenna. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1266–1269, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26803

메타 물질을 이용하여 소형화와 주파수 가변이 가능한 영차 공진 안테나

In this paper, a frequency tunable zeroth-order resonant(ZOR) antenna has been implemented. The ZOR characteristics of the proposed antenna is realized by using a composite right-and left-handed(CRLH) transmission line which consists of a rectangular slot on the ground plane of a mushroom structured antenna in order to minimize the antenna size. In addition, the tunable devices are introduced on the slotted ground plane for frequency tuning capability. Depending on the on and off states of the tunable device on the slotted ground plane, a shunt inductance value of the CRLH transmission line is changed and its resonant frequency becomes tunable. From the experimental results, the resonant frequency of the proposed antenna is changed from 4.92 GHz to 2.96 GHz. Additionally, the proposed antenna`s size is reduced by 94.24 % compared with the half-wavelength patch antenna.

일단 CRLH 전송선 구조를 이용한 소형 초광대역 대역 통과 여파기의 설계

본 논문을 통해, 메타 재질 특성을 가지는 CRLH-TL 구조를 이용하는 새로운 개념의 초광대역(UWB) 대역 통과 여파기의 설계법이 제시된다. 기존의 주기성 혹은 유한 다단 구조의 CRLH-TL가 아닌, 단일 구조만을 이용하여, 관내 파장의 0.25배 길이의 공진기를 기반으로 하는 여파기에서 가질 수 없는 초소형 구조를 형성한다. 특히 초광대역 통과 특성을 위해 필요한 강결합은 인터디즈틀 평행 결합 선로 양단의 접지된 스터브 구조를 통해 구현된다. 제안하는 설계 방안의 타당함은 전자기 모의 시험과 제작품의 측정을 통해 증명되며, 여파기의 전체크기가 '관내 파장/9.4'로의 축소, UWB 100 % 이상의 통과 대역폭, 1 dB 이하의 삽입 손실, 높은 평탄도의 군지연 등의 주파수 영역 특성 결과를 보인다. This paper presents a new design method of the Ultra-Wide-Band BandPass Filter using the CRLH-TL(Composite Right- and Left-Handed Transmission-line) having the Metamaterials' properties. Instead of the periodic type or many cells of the CRLH-TL, only the unit cell is used to miniaturize the target component, which can not be realized by the conventional quarter guided-wavelength resonator-based filters. Particularly, the strong coupling essential to the Ultra Wide Band is enabled by the interdigital coupled lines between the grounded stubs. The proposed design scheme is validated by the electromagnetic simulation and measurement of the fabricated filter which shows the total size of 'the guided-wavelength/9.4', the 100 % fractional bandwidth for the UWB, the insertion loss of less than 1 dB and the flat group-delay.