Composite Right/left-handed Transmission Line Research Articles

COMPACT ULTRA-WIDEBAND BANDPASS FILTER WITH SHARP ATTENUATION USING MODIFIED COMPOSITE RIGHT/LEFT-HANDED TRANSMISSION LINES

In this paper, the characteristics of novel modifled composite right/left-handed (CRLH) transmission lines are discussed, and an ultra-wideband (UWB) bandpass fllter (BPF) using the modifled CRLH transmission lines is presented. Design formulas of a novel modifled CRLH unit cell are theoretically derived. Based on the design formulas, the UWB bandpass fllter with three unit cells is designed, fabricated, and measured. The measurement results show that the UWB bandpass fllter has an insertion loss of less than 1dB, bandwidths of 2:9 » 49GHz, and a rejection of greater than 50dB at 5.8GHz.

Control of Phase and Phase Slope with Reinvestigation of 1D CRLH Transmission Lines

The conventionally classified waves are reclassified in this paper, including the waves associated with metamaterial (MTM) transmission lines. Various types of guided waves in periodic structures are analyzed for 1D Composite Right/Left Handed (CRLH) transmission lines (TL). In addition, dispersion diagrams for 1D CRLH, RH, and LH TLs are presented in terms of radiation conditions. We have refined the design equations of the conventional 1D CRLH TL and proposed a condition to realize the desired phase shift and its slope per unit cell. This condition has been applied to the conventional Wilkinson power divider and realized into MTM added <TEX>$90^{\circ}$</TEX> hybrid coupler. Based on the 10 dB return loss and the <TEX>$90{\pm}10^{\circ}$</TEX> phase shift, the bandwidths of the MTM added <TEX>$90^{\circ}$</TEX> hybrid coupler are 82.25% and 103.5% against the conventional 23% and 52.5%, respectively.

Time Reversal Applied to the Time Domain Response of a CRLH Transmission Line

In this letter, the concept of electromagnetic time reversal is applied to compensate for the non-linear phase response of a dispersive transmission line. To achieve a significant phase distortion on a short transmission line, a special type of transmission lines is chosen as an experimental platform. This special type is the so called composite right-left handed (CRLH) transmission line. The time domain response of the CRLH transmission line is calculated from a wideband frequency domain measurement.

Metamaterial Based Electronically-Scanned Circularly-Polarized LWA

An electronically-scanned circularly-polarized leaky-wave antenna (LWA) designed for ETC system is proposed in this paper. Based on the theory of composite right/left-handed (CRLH) transmission line (TL), the proposed antenna can fulfill the beam-scan from -6° to -21° in the half plane continuously at the fixed frequency of 5.8 GHz by tuning the bias voltage of varactors loaded on the CRLH TL. By loading corner-cut square patches, a circularly-polarized radiation is obtained at the main beam, and the maximum gain in the main beam direction keeps above 11 dB.

CRLH-TL을 이용한 2.45GHz 무선랜용 ZOR 안테나 설계

본 논문은 CRLH-TL(composite right left handed transmission line) 메타물질을 이용하여 2.45GHz 무선랜용 ZOR(zeroth order resonance) 안테나를 설계하는 것이다. 일반적으로 안테나는 파장에 대비한 선로의 길이에 따라 공진주파수가 결정되지만 ZOR 안테나는 파장의 길이와 상관없이 안테나의 공진주파수를 결정한다. 그러므로 소형화 할 수 있는 장점이 있으며 방사패턴 또한 등방성의 방사패턴을 가지는 장점이 있다. ZOR 안테나를 설계하기 위해 먼저 단위 셀 길이를 <TEX>${\lambda}/4$</TEX>의 길이보다 작도록 조정하여 균질한 매질 특성을 가질 수 있도록 하였다. 제안된 안테나는 공진 주파수의 감소와 대역폭의 증가를 위하여 CPW 급전을 사용하였고, 기존의 mush-room 형태의 CRLH-TL 보다 높은 인덕턴스와 낮은 캐패시턴스를 얻기 위하여 방사패치와 접지면 사이에 단락 스터브가 사용 되었다. ZOR(zeroth order resonance) antenna for 2.45GHz WLAN(wireless local area network) is designed by use of CRLH-TL(composite right left handed transmission line) meta-material. The electrical length of conventional antennas is determined generally according to the resonant frequency, whereas that of ZOR antenna can be determined without reference to the resonant frequency. Therefore ZOR antenna has advantage in miniaturization of antenna in comparison with conventional antennas. In order to design such ZOR antenna, first unit cell with electrical length shorter than a quarter wavelength at 2.45GHz is designed to the some characteristics of homogeneous medium. In order to decrease resonant frequency and enhance frequency bandwidth, the proposed antenna is fed by CPW(co-planar waveguide) and short stub between radiation patch and ground plane is used for obtaining both higher inductance and smaller capacitance than previous mush-room type of CRLH-TL.

A miniaturization of compact band-pass filter with radial stubs utilizing modified composite right/left-handed structure

A novel compact band-pass filter (BPF) with radial stubs (RS) utilizing modified composite-right/left-handed (CRLH) structure is proposed. A pair of microstrip RS is loaded as a combination of inductance and capacitance, which creates a transmission zero at the upper stop band. By introducing the magnetic coupling to the traditional interdigital coupled lines, two more transmission zeros are created. In addition, the fractional bandwidth is just more than 30% contrasted with super-wide BPF implemented by traditional CRLH transmission lines(CLRH-TL). Due to the good performance of out-of-band rejection and to guarantee the compactness in size, only one unit cell is adopted. The interdigital coupled lines are used to realize the strong coupling for the design which is shown to have the compact size of ( is the guided wavelength at the center frequency of 2.45 GHz). The insertion loss is no more than 1.7 dB in the pass band from 2.28 GHz to 2.62 GHz, and the spurious response up to is controlled effectively with more than 20 dB attenuation from 3.5 GHz up to 6.0 GHz, where is the pass band center frequency. Simulated and measured results are in good agreement with each other.

CRLH 전송선을 이용한 Marchand 발룬의 소형 격리 회로 설계

In order to obtain balanced ports matching and isolation between balanced ports of a Marchand balun, a compact isolation network is proposed. The proposed compact isolation network is designed using composite right/left-hand (CRLH) transmission line and compact phase inverter using CRLH transmission line unit cell. Also, design method and analysis of proposed isolation network are presented. The sizes of the proposed isolation networks are significantly reduced to and compared with the conventional isolation network of . The Marchand balun is operated at 2.45 GHz and is demonstrated through excellent experimental results.

Analysis and Design of Low Pass Filter using Unit Cell based on CRLH Transmission Line

In this paper, a unit cell for low pass filter design by using composite right and left-handed transmission line in conductor-backed coplanar waveguide is proposed. The characteristics of the unit cell are analyzed in order to design a low pass filter in small sizes. By changing the sizes of the unit cell, the parameters of right-handed and left-handed immittance components are changed and the desired characteristics of the unit cell are achieved. The equivalent circuit of the unit cell is extracted and analyzed either. As a result, the simulation results of the unit cell and the equivalent circuit are almost identified. The movement and energy distributions of electromagnetic field are shown to confirm the property of the unit cell. In the end, a low pass filter is demonstrated by cascading three proposed unit cells, which shows cutoff frequency of 1.53GHz and deep attenuation from 2.23GHz to 4.49GHz lower than -50dB.

Compact Equal and Unequal Dual-Frequency Power Dividers Based on Composite Right-/Left-Handed Transmission Lines

A novel approach using fully integrated composite right-/left-handed (CRLH) transmission lines (TLs) is proposed to design equal and unequal dual-frequency Wilkinson power dividers (WPDs) with controllable frequency ratio. Theoretical analysis indicates that the frequency ratio and the power-splitting ratio k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of the divider can be controlled by changing the element values and the number of the constructing cells of the CRLH TLs. Design formulas are presented to calculate the element values of the cells for a given frequency ratio. Dispersion relation, transmission/reflection coefficient, and Bloch impedance studies show that the Π-shaped unit cells have smaller size than the T-shaped counterparts but the same performance. For demonstration, one equal and one unequal dual-frequency WPDs operating at 2.45 and 5.2 GHz, respectively, are implemented. Measurements show that both the equal and unequal dividers have 17.5% and 26% relative bandwidths at 2.45 and 5.2 GHz, respectively.

Novel wide‐stopband bandpass filter with good frequency selectivity based on composite right/left handed transmission line

AbstractA novel wide‐stopband bandpass filter (BPF) with quasi‐elliptic response based on composite right/left handed transmission line (CRLH‐TL) is presented in this letter. Two compact CRLH‐TL resonators are utilized in the proposed wide‐stopband BPF. A magnetic cross coupling between the input and output ports is also used, which can generate three additional transmission zeros near the passband. Then, the frequency selectivity of the bandpass filter is greatly improved. The equivalent circuit method is used to analyze the mechanism of the magnetic coupling. A wide‐stopband BPF operating at 2.42 GHz is designed, simulated, and fabricated to demonstrate the performance of the proposed filter structure. The measured results show good agreement with the simulated ones. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2494–2497, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27104

CRLH 전송선로의 필터 특성을 이용한 트리플렉서와 삼중대역 증폭기에의 응용

In this paper, we proposed the triplexer using unit-cell of CRLH transmission line which has a bandpass characteristic to reduce adjacent channel interference. The input impedance of triplexer with each channel filter is operated open-circuit at the resonance frequencies of other channels. Such property is due to the combination a series and parallel resonance circuits of CRLH-TL unit-cell. The measured triplexer results are showed a measured insertion loss of each channel, less than 1.5 dB, matching at each port, less than 15dB and isolation between channel, better than 25 dB. Also, to validate the triplexer, a small signal amplifier with triple-band is designed and tested. the measured amplifier results show good agreements with prediction.

LTCC를 이용한 GPS와 WLAN 대역통과 여파기

본 논문은 LTCC를 이용하여 구현된 GPS와 WLAN용 대역통과 필터 설계방법을 제안한 것이다. 여기서 구현한 여파기는 버터워스 저역통과 여파기와 CRLH(Composite Right/Left-Handed) 전송선로의 고역통과 특성을 결합한 대역 통과 여파기를 설계하였다. 이렇게 설계된 여파기는 유전율 7.2의 그린쉬트를 이용한 LTCC 공정을 사용하여 1.5 GHz의 GPS와 2.4 GHz의 WLAN 대역의 대역통과 여파기를 제작하였다. 제작된 여파기의 삽입손실 결과는 1.5 GHz GPS대역에서 1.66 dB 또, 2.4 GHz WLAN 대역에서는 3.20 dB를 만족하는 대역통과 특성을 얻었다. This paper presents a bandpass fitler of GPS and WLAN band based on LTCC. The structure of bandpass fitler consists of a Butterworth lowpass fitler and highpass filter using CRLH (Composite Right/Left-Handed) transmission line. Using green sheet with dielectric constant 7.2, we fabricated the bandpass filter that satisfied GPS and WLAN band characteristics. We are implemented the bandpass filter at center frequency 1.5 GHz (GPS) and 2.4 GHz (WLAN). Its insertion loss are 1.66 dB at GPS and 3.20 dB at WLAN respectively.

Miniaturized Ring Coupler with Arbitrary Power Divisions Based on the Composite Right/Left-Handed Transmission Lines

A novel and miniaturized ring coupler capable of presenting arbitrary power divisions is proposed using the composite right/left-handed (CRLH) transmission lines. The unbalanced CRLH transmission lines that can be easily tailored to implement transmission lines of high or low Bloch impedance are applied to enhance the coupler's capability of arbitrary power divisions. To support our idea, a ring coupler that offers a 6 dB power division ratio and occupies only 44% of the conventional footprint was experimentally realized. Experimental results agree well with the simulation data. The proposed CRLH configuration demonstrates an alternative for implementing a compact ring coupler with arbitrary power division ratios.

IMPROVED CRLH-TL WITH ARBITRARY CHARACTERISTIC IMPEDANCE AND ITS APPLICATION IN HYBRID RING DESIGN

An improved designable composite right/left-handed transmission line (CRLH-TL) is presented in this paper, whose operating frequency-band and transmission characteristics can be tuned, respectively, by three structure variables. The equivalent characteristic impedance is studied carefully, and CRLH-TLs with arbitrary characteristic impedances are obtained. Some useful empirical formulae are derived for engineering application. Then, a sample of 50-› CRLH-TL, which can be used directly as a wide-band fllter, is fabricated with the center frequency of 2.8GHz. The measured results show that a relative 3-dB bandwidth of 74.6% is achieved, in good agreement with the simulated results. Moreover, the phase- frequency responses of our proposed CRLH-TLs are discussed in detail. A novel hybrid ring is then proposed, where 70-› CRLH-TL is used. At the center frequency of 5.8GHz, equal power dividing is achieved with return loss and isolation more than 20dB and 30dB, respectively. The sample is flnally fabricated and good agreements among theoretical analysis, simulated results, and measured results are obtained.

Planar diplexer using composite right-/left-handed transmission line under balanced condition

A novel high-performance planar diplexer is proposed. The filtering response of a balanced composite right/left-handed transmission line (CRLH-TL) is investigated first. The diplexer is then implemented based on two balanced CRLH-TLs. Simulated results and experimental verifications are provided, and simulation results are found to be consistent with measurement results. This diplexer shows advantages in terms of the low loss, high isolation, easy fabrication and integration with other circuits.

An Omnidirectional Small Loop Antenna Based on First-Negative-Order Resonance

A compact first-negative-order resonance-based small loop antenna is proposed which consists of two unit cells of composite right-left hand transmission line (CRLH TL). By folding one of the unit cells to the bottom layer, higher radiation efficiency and omnidirectional radiation property can be achieved. A prototype antenna is fabricated and measured. The size of the proposed antenna is only 10.45 mm × 7 mm (or 0.062λ0 × 0.042λ0) at 1.78 GHz. The measured antenna bandwidth is 6.4 MHz and gain is 0.53 dBi.

NOVEL COMPOSITE RIGHT/LEFT-HANDED LEAKY-WAVE ANTENNAS BASED ON THE FOLDED SUBSTRATE-INTEGRATED-WAVEGUIDE STRUCTURES

In this paper, novel composite right/left-handed (CRLH) leaky-wave antennas based on folded substrate-integrated-waveguide (FSIW) structures are proposed. The proposed leaky-wave antennas were realized by periodically loading the radiating slots on the top metallization of the FSIW-based CRLH transmission lines. The structural advantages of the FSIW combined with the unique dispersion characteristics of the CRLH transmission line enable the proposed leaky-wave antennas to present continuous beam-scanning capability from backflre to endflre directions, occupy smaller footprint size, and provide more design ∞exibility than the conventional CRLH leaky-wave antennas. Two of such CRLH leaky-wave antennas were developed. In addition to the continuous beam scanning, it is found that the radiation e-ciency and polarization of the FSIW-based leaky- wave antennas can be easily tuned by means of the slot size and slot orientation, respectively, indicating their potential for versatile applications. Calculated and experimental results are presented and compared. A good agreement is obtained. To the best of our knowledge, it is the flrst time that the leaky-wave antenna exploits both of the dispersion behavior of the CRLH transmission lines and the structural beneflts of the FSIW conflguration.

COMPACT MULTI-BAND LOOP ANTENNAS USING CPW-BASED CRLH QUARTER-WAVE TYPE RESONATORS

In this paper, a novel approach to design compact multi-band loop antennas is proposed. This type of antennas is composed of coplanar waveguide (CPW)-based composite right/left- handed (CRLH) quarter-wave type resonators, and developed on a vialess single layer. Both size reduction and low frequency ratios have been achieved, proflting from the employment of quarter-wave resonators and the high nonlinearity in the left-handed region of CRLH transmission line (TL) dispersion diagram. A sample prototype operating at three negative modes (1.92/2.15/2.64GHz) with an overall size of 29 £ 21:3 £ 1:0mm 3 was manufactured and measured. Measured results show good agreement with EM simulation, exhibiting good impedance matching as well as stably omni-directional radiation patterns at the three operating modes.

Composite Right- and Left-Handed Traveling-Wave Field-Effect Transistors

We introduce a composite right- and left-handed travelling-wave field-effect transistor (CRLH TWFET) for developing large-scale platform to support left-handed waves. The device represents two electromagnetically coupled CRLH transmission lines by capacitance and FET transconductance. Owing to the couplings, two different modes can support waves in CRLH TWFETs. It was experimentally established that waves supported by one of the modes were amplified, while those supported by the other mode were significantly attenuated. To quantify the wave propagation in CRLH TWFETs, we developed a numerical model based on the transmission line theory that well simulated measured results. This paper discusses the results of numerical calculations that validate the design criteria of CRLH TWFETs.

Theoretical Study on Creation Mechanism of Self-resonance Occurred in Unit Cells of Multilayer CRLH Transmission Lines

Theoretical Study on Creation Mechanism of Self-resonance Occurred in Unit Cells of Multilayer CRLH Transmission Lines