Finite difference time domain analysis of extended composite right/left‐handed transmission line equations

In this article, a set of differential equations to model the behavior of the extended composite right/left handed transmission line in time domain is proposed. These equations are solved by an explicit finite difference time domain algorithm. To investigate the numerical stability of the proposed algorithm, the amplification matrix is extracted. The results of the proposed algorithm are confirmed by the results of the Agilent ADS commercial software. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:68–76, 2014.     

Dual extended composite right/left‐handed transmission line metamaterial

The new concept of dual extended composite right/left‐handed transmission line (D‐ECRLH TL), with 2 right handed and 2 left handed frequency bands is presented. The D‐ECRLH TL and extended composite right/left handed transmission line are structurally dual. Therefore, the proposed TL shows the dual properties of the ECRLH TL. The D‐ECRLH indeed behaves as a dual‐band bandstop filter, in opposition to the ECRLH which is a dual‐band bandpass one. In contrast, the D‐ECRLH creates an unlimited LH bandwidth. In this article, the transmission parameters and the fundamental properties of the D‐ECRLH TL (dispersion and impedance diagrams) are investigated. The results show that the proposed structure is suitable to design the quad‐band microwave circuits and systems. A prototype of the proposed D‐ECRLH unit cell is realized by the microstrip technology. The good agreement between the measurement and simulation results confirms the realizability of the proposed structure.     

Wideband leaky‐wave antenna with consistent gain and wide beam scanning angle based on multilayered substrate integrated waveguide composite right/left‐handed transmission line

In this article, a wideband leaky‐wave antenna is designed for consistent gain and wide beam scanning angle by using the proposed multilayered substrate integrated waveguide (SIW) composite right/left‐handed transmission line (CRLH TL). The proposed SIW CRLH structure consists of two parts: an interdigital fingers slot of rotating 45° etched on the upper ground of the SIW, and a rotated parasitic patch beneath the slot. Due to the continuous phase constants change from negative to positive values of the proposed SIW‐CRLH under the balanced condition, the designed LWA can achieves a continuous beam‐scanning property from backward to forward over the operating frequency band. The designed antenna is fabricated and measured, the measured and simulated results are in good agreements with each other, indicating that the designed antenna obtains a measured continuous main beam scanning from backward ?78° to forward +76° over the frequency range from 7.7 to 12.8 GHz with a consistent gain of more than 9.5 dB. Besides, the designed antenna also exhibits a measured 3‐dB gain bandwidth of 45.1% with maximum gain of 15 dB. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:731–738, 2016.     

Design and optimization of CPW‐based composite right/left‐handed transmission line

This article presents a systematic design procedure of CPW‐based Composite Right/Left‐Handed Transmission Line (CRLH TL), including the initial design and optimization algorithm. A Graphical User Interface (GUI) is provided to help inexperienced users synthesize CRLH at any given transition frequency, without tedious tuning or iterative trial. An improved fitness function based on Genetic Algorithm (GA) is presented to reduce the return loss and diminish the bandgap. This design procedure is fast and available, and has been verified by both measurement and full‐wave simulation results. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Design and application of composite right/left‐handed transmission line based on complementary meander archimedean spiral resonator

A novel composite right/left‐handed transmission line based on the complementary meander Archimedean spiral resonator (CMASR) is proposed and investigated in detail. The composite property of the proposed structure is demonstrated and the right‐handed frequency band is initially pointed out for the structure derived from the complementary Archimedean spiral resonator (CASR). One modified method of extracting the lumped elements based on the analytical analysis is proposed to investigate the equivalent circuit model. The results indicate that this method can accelerate the extracting process effectively and the circuit model using the extracted elements can predict the property of the given structure excellently. Then, the influence of primary geometrical parameters is investigated through the parametric analysis, which provides the directive guideline. When compared with CASR, CMASR can lower the operating frequency further with keeping the effective area roughly constant. To explore and validate the composite property, one broadband bandpass filter is designed through tuning the left‐ and right‐handed frequency bands into the quasi‐balance condition. The measured results indicate that the fractional bandwidth is about 88.3%. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012.     

Multimode resonator based on composite right‐/left‐handed transmission line for UWB bandpass filter application

A new multimode resonator (MMR) using composite right‐/left‐handed transmission line (CRLH TL) is proposed and discussed. The CRLH TL structure is constructed by cascading interdigital coupled microstrip line sections on which short‐ended stepped impedance stubs are loaded. Dispersion characteristic of the transmission line structure is obtained using the Bloch–Floquet theory. The resonator, which has multiresonances electrical behaviors, is especially suitable in ultrawideband (UWB) applications. An UWB filter is presented as an illustration. With transmission zeros introduced at upper stopband, the filter has a sharp skirt performance. In addition, rejection level at lower stopband also gets enhanced due to direct current suppression effects of the multimode resonator. The filter prototype is implemented and measured. The measured results validate the theoretical analysis and show that the filter has a sharp skirt and an out‐of‐band rejection level as good as 38 dB. Meanwhile, return loss is better than 16 dB. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:815–824, 2015.     

Bandwidth and gain‐enhanced composite right/left‐handed antenna for ultra‐wideband applications

A coplanar waveguide‐fed metamaterial antenna is presented for ultra‐wideband (UWB) applications. The proposed antenna is designed with single unit‐cell composite right/left‐handed transmission line (CRLH‐TL) loaded with a split‐ring resonator (SRR). The UWB characteristic is obtained by merging the zeroth‐order resonance of CRLH‐TL with two additional resonances due to the ground plane and SRR respectively. Subsequently, a partial reactive impedance surface is embedded on the rear side of the proposed antenna to enhance the realized gain without affecting the UWB response. The overall size of the antenna is 0.241λ_o x 0.267λ_o x 0.013λ_o (28.8 x 32 x 1.6 mm³), where λ_o is the free space wavelength at 2.51 GHz. The measured results indicate –10 dB fractional bandwidth of 139.19% (2.51‐14 GHz) with realized gains of 2.3, 4.6, and 6 dBi at the resonant frequencies 4, 7.84, and 10.29 GHz respectively. The measured peak realized gain is 6.6 dBi at 10.6 GHz. The radiation efficiency is above 63.85% for the entire UWB range with a peak value of 86.84%. A fairly stable group delay with variation within 1 ns is obtained throughout the operating frequency band. A good agreement has been observed between the measured and simulated results.     

Modeling and synthesis of the interdigital/stub composite right/left‐handed artificial transmission line

An efficient design procedure, including both analysis and synthesis, is proposed for Composite Right/Left Handed (CRLH) interdigital/stub structures. Improved models are developed for both the interdigital capacitor and the shorted stub inductor including its ground via hole. Subsequent optimal formulas are recommended to model these components with their parasitic effects. The models and formulas are verified by both full‐wave and experimental results. A CAD program with a friendly GUI, available online, is provided and its operation is described in details. This program allows a very fast design of the CRLH structure, and its synthesis parameters are proven very accurate without any full‐wave optimization. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Miniaturized low‐profile antenna based on uniplanar quasi‐composite right/left‐handed metamaterial

In this article, a metamaterial‐based broadband low‐profile antenna is presented. The proposed antenna employed an array of uniplanar quasi‐composite right/left‐hand (CRLH) metamaterial cells. This structure contributes to exciting the operating modes in lower frequencies. The antenna has an overall electrical size of 0.75 × 0.60 × 0.07 λ₀³ (λ₀ is the center operating wavelength in free space) and provides a 25% measured bandwidth with the center frequency of 5.1 GHz and maximum gain of 6.6 dB. The proposed antenna is an appropriate candidate for WLAN, WiMAX, and other wireless communication applications.     

A compact transmission line with two pairs of composite right/left‐handed passbands

A compact transmission line with two pairs of composite right/left‐handed (CRLH) passbands is investigated, and its equivalent circuit is proposed. Compared with the conventional CRLH transmission line (CRLH‐TL), we use the rectangular patches with meander lines and the T‐shaped defected ground structures (T‐DGS) to model the other two resonators, which realize the second left‐ and right‐handed bands. The dispersion relations are analytically derived using the equivalent circuit and Bloch‐Floquet theory. The five‐stage CRLH‐TL is fabricated, and the measured results are in agreement with those of simulation. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Band‐notched ultra‐wideband antennas using nonperiodic composite right/left‐handed resonators

This article investigates the characteristics of a single/double‐cell composite right/left‐handed (CRLH) resonator and its application on multiple band‐notched ultra‐wideband (UWB) antennas while suggesting an accurate design procedure. Periodicity assumption and calculating a dispersion diagram allow band‐notched frequencies to adequately predict prior to antenna design. Zeroth‐order resonance (ZOR) frequency due to the CRLH characteristics of a mushroom resonator and higher‐order resonance frequencies are predictable through the hypothetical dispersion diagram. To demonstrate this method, compact, printed, ultra‐wideband circular monopole antennas with four/five‐band notched characteristics using a single/double mushroom resonator are presented. The effects of mushroom cell size on ZOR and the other band notched resonant frequencies are also investigated. The numerical simulations show that the asymmetrical unit cell provides the capability to tune both ZOR and band notched frequencies. Comparison between the simulation and measurement results shows reasonable agreement.     

Composite right/left handed artificial transmission line structures in CMOS for controlled insertion phase at 30 GHz

Two CMOS integrated circuits are presented that utilize metamaterial composite right/left handed (CRLH) transmission lines (TLs) for zero insertion phase at 30 GHz. Specifically, 2 and 3 unit cell structures are presented with controlled insertion phase that is achieved by cascading lumped element capacitors and spiral inductors in an LC network configuration defining the TL unit cells. Furthermore, the fixed TL structures suggest the possibility of zero, advanced or delayed insertion phases by element variation, or by the use of simple active components. Simulation and measured results are in good agreement with CRLH TL theory, and display a linear insertion phase and flat group delay values that are dependent on the number of unit cells with an insertion loss of ～0.8 dB per cell. These findings suggest that such high speed CRLH TLs structures can be implemented for linear array feeding networks and compact antenna designs in CMOS at millimeter wave frequencies. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

基于复合左右手结构的新型超宽带巴伦

基于复合左右手(CRLH)结构的非线性相位特性,设计了一种新型的超宽带威尔金森功分器巴伦.该巴伦利用一个单元的CRLH结构代替传统微带线构成分支臂.仿真和实验结果表明该新型的巴伦具有高达120%的相对阻抗带宽、112%的相对相位差带宽、体积小、制作简单、易与MIC/MMIC技术集成等优势.     

Wideband dual‐element leaky‐wave antenna with constant gain and enhanced broadside radiation bandwidth using multilayered composite right/left‐handed substrate integrated waveguide

In this study, a wideband dual‐element leaky‐wave antenna (DE‐LWA) is proposed to achieve constant gain and wideband broadside radiation by using multilayered composite right/left‐handed substrate integrated waveguide. The proposed DE‐LWA consists of two leaky‐wave radiator elements which are with slanted and vertical interdigital fingers slot arrays. To verify the simulated results, the proposed DE‐LWA is fabricated and measured. The measured results are in good agreement with the simulated ones, indicating that the fabricated antenna obtains broadside gain of 12.5 dB with variation of 1.0 dB over the frequency range of 8.725‐9.25 GHz (5.84%). Moreover, the proposed DE‐LWA also can provides a beam scanning property from backward ?80° to forward +80° over the frequency range from 7.4 to 12.7 GHz with a constant gain of more than 10 dB. Besides, the electromagnetic performances of this work are better than those of the recently reported similar work in the references.     

Broadband magic‐Ts with the use of coupled‐line directional couplers and left‐handed transmission line sections

The problem of broadband magic‐T realization with the use of coupled‐line directional couplers and left‐handed (LH) transmission‐line sections has been comprehensively investigated. Broadband amplitude characteristics of the proposed networks are ensured with the use of coupled‐line couplers, whereas the required phase characteristics have been achieved by the appropriate selection of right‐ and left‐handed transmission line sections. To analyze the properties of the proposed networks, a model of an ideal left‐handed transmission line has been utilized. The presented concept has been verified by two designs of broadband magic‐Ts operating in 2.5–3.5 GHz and 0.8–2.3 GHz, respectively. The obtained results proved that the proposed magic‐T networks allows one to obtain broadband amplitude and phase responses together with its compact structure. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:513–521, 2014.     

Dual‐band artificial transmission lines branch‐line coupler

By using short‐circuited Composite Right/Left‐Handed Transmission Lines as loading stubs, and Purely Right‐Handed Artificial Transmission Lines, a Dual‐Band Branch‐Line coupler is presented. The adoption of such technologies adds degrees of freedom with respect to other already proposed design techniques, thus allowing the development of a very compact device, and a larger flexibility in the choice of the two operating frequencies and corresponding bandwidths. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Fine control of filter performance based on composite right/left‐handed metamaterial technology

Composite right/left‐handed (CRLH) metamaterial unit cell whose ground‐plane is defected with a rectangular dielectric slot is used to develop a single and multi‐pole pole bandpass filter. The unit cell comprises of serially connected interdigital capacitors whose junction is connected to a short‐circuited inductive stub. By defecting the ground‐plane of the unit cell's structure with a dielectric slot, which is located immediately below the unit cell, enables substantial tuning of the filter's center frequency in the order of 26.5%. This is achieved with minimal effect on the unit cell's insertion and return‐loss performance including its selectivity. The filters were fabricated on conventional dielectric substrate and their performance measured to verify the design methodology. The proposed technique eases the trade‐off constraints and makes possible the realization of challenging filter specifications constituted from CRLH unit cells using distributed transmission‐lines. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:39–45, 2014.     

Harmonic suppressed bandpass filter using composite right/left handed transmission line

A wideband composite right/left handed transmission line (CRLH TL) in conjunction with its corresponding equivalent circuit model is studied based on a cascaded complementary single split ring resonator (CCSSRR).The characterization is performed by theory analysis,circuit simulation,and full-wave electromagnetic (EM) simulation.The negative refractive index (NRI) and backward wave propagation performance of the CRLH TL are demonstrated.For application,a bandpass filter (BPF) with enhanced out-of-band selectivity and harmonic suppression operating at the wireless local area network (WLAN) band is designed,fabricated,and measured by combining the CRLH TL with a complementary electric inductive-capacitive resonator (CELC).Three CELC cells with wideband stopband performance in the conductor strip and ground plane,respectively,are utilized in terms of single negative permeability.The design concept has been verified by the measurement data.     

Crosstalk analysis of multi‐microstrip coupled lines using transmission line modeling

This article presents a new analytical method to predict crosstalk of a homogeneous terminated two microstrip coupled lines over a ground plane using transmission line theory. The derived formula is frequency and location dependent, which can be used to quickly estimate the crosstalk of a coupled line. Also, the effect of the geometrical parameters of the lines and load are included in the derived formula. Presented method can be used for the other types of coupled lines including lossy or lossless lines. To verify the accuracy of the introduced method, a few microstrip coupled line structures with different geometrical parameters are considered numerically and experimentally. The results of crosstalk based on the proposed analytical methods, simulation study using high frequency structure simulator and those obtained by measurements are reported and compared with each other. It is shown that our proposed method accurately estimates the amount of crosstalk for a two microstrip coupled lines.     

Modal analysis of the microwave frequency response and composite right‐/left‐handed operation of a rectangular waveguide loaded with double positive and double negative materials

This article presents a theoretical study of the electromagnetic wave propagation in a rectangular waveguide, loaded with double positive (DPS) and double negative (DNG) dielectrics. The frequency response of the waveguide is analyzed using a modal technique. The results show that when at least one of the dielectrics is a DNG material the cutoff frequency of the waveguide is much more lower than the cutoff frequency of the DPS loaded or the empty waveguide. This interesting property means that very low frequency signals could be guided by structures that have very small size. Properties of composite right‐ and left‐handed wave propagation are also observed as well as the characteristic stop‐band between the frequency regions in which RH and LH wave propagation occurs. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.