Composite Right/left-handed Transmission Line Research Articles

Design of high power capacity phase shifter with composite right/left‐handed transmission line

AbstractBased on the structure of composite right/left‐handed transmission line (CRLH‐TL), a novel phase shifter with high power capacity is developed. A new and an accurate equivalent circuit of the CRLH‐TL element is utilized and validated in the phase shifter design. Because the switches are incorporated on the fingers of the CRLH‐TLs, the power going through a single switch is only a fraction of that through the entire phase shifter. As a result, the power handling capacity of the proposed phase shifter can be greatly increased. In addition, multiphase phase shifters can be realized with multiple switches incorporated in a single CRLH‐TL element. A 4‐bit phase shifter and a multiphase phase shifter are designed and tested. The power capacity of the multiphase phase shifter is measured to be higher than most of the conventional phase shifters. The presented phase shifter also possesses other advantages such as low cost, compact size and ease of fabrication. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:119–124, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26505

Novel Compact Dual-Band Rat-Race Coupler Combining Fractal Geometry and CRLH TLs

A super compact fractal-shaped composite right/left handed (CRLH) rat-race coupler (RRC) is proposed for the first time by skillfully combining two circuit schematics of the RRC operating at two arbitrary frequencies. For dual-band (DB) purpose, novel circuit schematics of RRC are deducted, and close-form formula and design procedures are derived in detail. The CRLH transmission line (TL) consists of lumped elements for the left handed part and Koch-shaped microstrip lines (MLs) for the right handed part. Since conventional RRC exhibits two types of unique branches, the DB design often suffers a tedious process. By employing the CRLH TL, the realization of a DB RRC becomes much easier. Moreover, constructing the microstrip lines as Koch curves enables the compactness of the circuit. For verification, a coupler operating at 0.75 and 1.8 GHz is fabricated and measured. Consistent results between simulation and measurement have confirmed the design and shown that the RRC with an area of 10.2% of its conventional counterpart owns excellent in-band performances.

차단 주파수 이상에서 평형 조건을 만족하는 CRLH 직각 도파관

In this paper, a composite right-/left-handed(CRLH) rectangular waveguide satisfying a balanced condition above the cut-off frequency is presented. The proposed structure consists of one shorted stub and two twisted H-plane irises which produce an effectively negative permeability and permittivity, respectively. The CRLH structure can independently control the series and shunt resonance frequencies of a CRLH transmission line which determine the left-handed(LH) and right-handed(RH) bands due to a minimized coupling between a shorted stub and twisted H-plane irises. Thus, the design of the CRLH waveguide satisfying a balanced condition is possible. To analyze the CRLH structure, a crossly connected equivalent circuit is derived. The simulated and measured results confirm that the proposed CRLH waveguide has a transmission property without a band gap among the LH and RH bands.

Dual-band push-push OSC using CRLH transmission line and tunable negative resistance based on pin diode

In this article, the dual-band oscillator (OSC) using the composite right/left-handed (CRLH) transmission -line (TL) and the tunable negative resistance based on the pin diode is presented. It is demonstrated that the CRLH TL can lead to metamaterial transmission line with the dual-band tuning. The dual-band push-push oscillator design approach demonstrated in this work enables higher OSC frequency operation, lower noise performance, and smaller size, which is attractive for military radar frequency source applications. The phase noise of OSC is from −110.12 to −111.27 dBc/Hz @ 100 kHz in the tuning range, 4.05–4.11 GHz for the forward bias of the pin diode, whereas that of OSC is from 112.26 to −113.13 dBc/Hz @ 100 kHz in the tuning range, 9.97–10.17 GHz for the reverse bias of the pin diode. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26072

Second harmonic generation with zero phase velocity waves

We design a dual-band nonlinear composite right-left handed transmission line with phase-matching achieved between the fundamental frequency and second harmonic when both interacting waves have zero phase velocity. Additionally, we show that such a transmission line supports a new regime where the generation of backward second harmonic waves is achieved from a backward fundamental frequency wave.

Zeroth-Order Resonators With Variable Reactance Loads at Both Ends

Effects of the reflection condition at both ends of a zeroth order-resonator are investigated. The proposed resonator is composed of a composite right/left-handed transmission line (CRLHTL) and two reactive elements as reflectors at both ends. The load reactance at one end is chosen as the complex conjugate of the other. The balanced case without bandgaps between right- and left-handed passbands, as well as the unbalanced cases, are discussed for CRLHTLs employed in the resonators. The superposition of stored energies of series resonance in the series branch and parallel resonance in the shunt branch in the ladder network can be continuously and arbitrarily controlled by changing only the load reactance at the terminals. For unbalanced cases, the resonance occurs within the bandgap. Coexistence of the two different resonances is verified by directly observing the near-field distribution of the resonator in the numerical simulation and the measurement.

Extraction of capacitive profiles with a planar metamaterial sensor

The extraction of capacitive profiles with a planar metamaterial sensor is presented. The sensor is build up using a tailored Composite right/left-handed transmission line (CRLH-TL). The capacitance values along the line can be evaluated by measuring the broadband line input impedance followed by applying a dedicated extraction method based on classical network synthesis with a combination of the Cauer canonical forms (CCF) I and II to obtain the values of the corresponding lumped elements in the equivalent circuit. Two prototype sensors have been developed and tested to prove the concept. The areas of application of these types of sensors are transportation of materials in industrial processes where the position of the Material Under Test (MUT) is of interest and can be derived from the changes in the capacitances.

Control of the sensitivity of CRLH interdigital microstrip balanced structures using a co-design genetic algorithm approach

A fully automated tool for designing CRLH interdigital microstrip structures using a co-design synthesis computational approach is proposed and demonstrated experimentally. This approach uses an electromagnetic simulator in conjunction with a genetic algorithm to synthesize and optimize a balanced CRLH interdigital microstrip transmission line. The high sensitivity of a long balanced transmission line to fabrication tolerances is controlled by the use of a high precision 3D simulator. The 2.5D simulator used was found insufficient for a large number of unit cells. A 13 UC CRLH transmission line is designed with the proposed approach. The response sensitivity of the balanced transmission lines to the over/under-etching factor is highlighted by comparing the measurements of four lines with different factors. The effect of over/under-etching is significant for values larger than 10 μm.

High-Gain Array Antenna Based on Composite Right/Left-Handed Transmission Line

In this paper a metamaterial-inspired antenna with high gain and good directivity is designed. Based on the concept of composite right/left-handed transmission line (CRLH-TL), the proposed antenna is realized based on three leakage wave unit cell and a left handed circular ring slot incorporated on the surface. The maximum achievable gain at the resonant frequency of 5.6GHz is 6.933 dBi, and the return loss at 5.6 GHz can be –20 db. This proposed design has a simple structure and a compact dimension of 35 mm*40 mm*1 mm, which is suitable for particular wireless communication application such as WiFi and WLAN.

Active Microwave Metamaterials Incorporating Ideal Gain Devices.

Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL) incorporating ideal gain devices such as constant negative resistance. With realistic lumped element values, we have shown that the negative phase constant of this kind of transmission lines is maintained (i.e., left-handedness kept) while gain can be obtained (negative attenuation constant of transmission line) simultaneously. Possible implementation and challenging issues of the proposed active CRLH-TL are also discussed.

A uneven Doherty power amplifier using anticoupled power divider and composite right/left-handed transmission lines

A uneven Doherty power amplifier using anticoupled power divider and composite right/left-handed transmission lines (CRLH-TL) is proposed for efficiency and linearity improvement.Uneven power divider is achieved by anticoupled line divider and CRLH-TL, the structure is used to deliver more input power to the peaking amplifier than the main amplifier. The CRLH-TL with lead 90° phase shifter at the input of maim amplifier is designed to flexible variation of power division ratio and phase, besides, anticoupled power divider to suppress the second harmonic of front class input. The drain efficiency of 45.2 and 39.3% has been measured at the saturated output power of 43 dBm and 6-dB back off, respectively. Furthermore, the third-order intermodulation distortion performance and ACLR is improved as much as 5–6 dB when compared with conventional uneven Doherty amplifier. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:322–324, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25715

Design of a Novel CRLH-TL Structure

Two new types of interdigital capacitors (IDC) are proposed to be used in a novel Composite Right/Left-Handed Transmission Line (CRLH-TL) structure. The LC parameters of the traditional and novel IDC are respectively extracted for comparisons with Ansoft HFSS9 full-wave simulation. In contrast with traditional structure, such two new IDC enhance the capacitance values dramatically by about 38.7% and 100%, respectively, compared with the traditional structure within the same size of etched area. Also dispersion relationships are calculated by both simulation and Bloch theorem. A one dimension (1-D) CRLH-TL structure consisting of such new IDC and meandering grounded inductors is designed, modeled and simulated. The presented structure is able to operate within a much lower and wider Left-handed (LH) frequency band than traditional ones.

Novel dual-band hybrid coupler using improved simplified CRLH transmission line stubs

In this article, a novel dual-band hybrid coupler is designed by adopting improved simplified composite right-/left-handed (ISCRLH) transmission line (TL) stubs.An ISCRLH TL stub is composed of two ISCRLH TL unit cells with input and output uniform TL sections at the terminals, which can produce specified impedance and phase shift at two (arbitrary) different frequencies. The conditions for synthesizing the dual-band ISCRLH TL stub are discussed in detail, and then such a stub is applied to implement a novel dual-band hybrid coupler in microstrip configuration, and excellent agreement between the simulated and measured results is achieved, which reveal good performance and dual-band operation. The novel device is small, fully planar, and easily designed and fabricated. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2473–2476, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25491

제어 가능한 전송 영점을 갖는 CRLH 전송 선로

In this paper, a novel CRLH-TL unit cell with controllable transmission zeros was proposed. Proposed composite right/left handed transmission line(CRLH-TL) unit cell is implemented in the form of the metal-insulator-metal(MIM) capacitors, the microstrip stub inductors, and the co-planar waveguide(CPW) inductor. And this proposed CRLH-TL generates two transmission zeros in lower/upper passband by the effort of electromagnetic couplings between each MIM capacitors and microstrip stub inductors. Using this proposed CRLH-TL, broad bandpass filter for UWB system was designed and fabricated. The measured results reveal that the two transmission zeros are observed in lower/upper passband and the overall size of the filter, excluding the feed line is about 8 mm8 mm, less then /4 on electric size.

A 3‐bit phase shifter with high‐power capacity based on composite right/left‐handed transmission line

AbstractA miniaturized 3‐bit phase shifter with high power‐handling capacity is designed based on the use of a single composite right/left‐handed transmission line (CRLH‐TL) unit cell. PIN diodes mounted on the fingers of the CRLH‐TL unit cell are used as switches to control the phase shift of the input signal. Different phase shifts are achieved by using different states of the switches determined by the 3 controlling bits of the phase shifter. The surface current flowing through each of the switches is only a fraction of the total current through the device, so the power handled by each of the PIN diodes is much smaller than the total power through the device. The phase shifter is designed to provide a phase‐shift range from 0° to 157.5° at a step 22.5° and operate in the frequency band from 9 to 10 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has much higher power‐handling capacities than that of the PIN diode and low insertion losses across the operating frequency band. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1778–1782, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25346

Design of a broadband balun based on composite right/left handed structure

AbstractA new printed Wilkinson balun based on the nonlinear phase characteristics of composite right/left handed (CRLH) structure is presented.The new device, which differs from the traditional CRLH balun, is composed of a Wilkinson power divider, a distributed CRLH transmission line (TL), and a conventional TL. It can be easily applied to MIC/MMIC circuits. Full‐wave simulations and measurement results verify the effectiveness of the new structure. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1310–1313, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25189

Dual‐band branch line coupler based on composite right‐/left‐handed transmission lines with series capacitors only

AbstractThis article demonstrates, for the first time, a dual‐band branch line coupler based on composite right‐/left‐handed transmission lines with series capacitors only.The complete elimination of shunt inductors provides a potential for the proposed CRLH transmission lines to be applicable to high frequencies, especially without via‐holes in microstrip lines. Experimental results are in excellent agreements with the simulated results. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1046–1048, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25123

Numerical Simulations of Backward-to-Forward Leaky-Wave Antenna with Composite Right/Left-Handed Coplanar Waveguide

A composite right / left-handed (CRLH) coplanar waveguide (CPW) structure and its leaky-wave antenna (LWA) with continuous backward-to-forward scanning applications are proposed. The structure of the CRLH transmission line (TL) is composed of split-ring resonators (SRRs) for left-handed (LH) series capacitance and short-circuited stubs connected between the CPW central signal line and the ground for LH shunt inductance, while the unavoidable right-handed (RH) parasitic effects series inductance and shunt capacitance are generated by wave propagation through the host transmission line. The dispersion relations are calculated and compared with the equivalent circuit model method and 3D full-wave simulations, which can be used to determine the physical dimensions of the CRLH-CPW, such as in the balanced CRLH-TL case. As a main example, a CRLH-CPW-LWA operating from 1.67 GHz to 1.80 GHz with the dispersion characteristics of the balanced CRLH-TL case shows continuous leakage frequency band (fast wave region) from LH (phase constant β < 0, 1.67 < f < 1.74 GHz) to BH (β > 0, 1.74 < f < 1.80 GHz) state through the transition frequency point (β = 0, f = 1.74 GHz), whereas conventional LWAs operated in RH state only provide forward scanning capabilities (β > 0).

Shielded Structure of Composite Right/Left-Handed Transmission Line Using Substrate Integrated Waveguide and Floating-Conductor

A composite right/left-handed transmission line (CRLH-TL) using substrate integrated waveguide (SIW) with floating-conductor (SIW-type CRLH-TL) for microwave and millimeter wave frequencies has been proposed by the authors. This paper proposes a new configuration that is shield type of the SIW-type CRLH-TL, which can suppress the radiation from the exposed floating-conductors, and shows that even if the shielded structure is used, the SIW-type CRLH-TL supports the LH mode as well as the prototype. Proposed CRLH-TL consists of a SIW with slot apertures (part 1), a dielectric film with floating-conductors (part 2) and a SIW without lower conductor (part 3). A shielded SIW-type CRLH-TL for X - K band (with wide LH mode bandwidth of 6GHz and transition frequency of 16GHz) that satisfies the balance condition is designed. Dispersion diagram and S-parameters are derived numerically, and typical field distributions of RH and LH transmission and the zeroth-order resonance are shown. Measured result agrees well with theoretical result, by considering the accuracy performance and loss factors of the fabricated CRLH-TL. Proposed CRLH-TL has advantage of simple manufacturing, because the parts 1 - 3 are composed of simple planar periodic structure. It is expected to be one of the basic structure of CRLH-TL or components such as LH coupler above 10GHz or millimeter wave frequency.

Extraction of Capacitive Profiles with CRLH Transmission Lines

Different methods for extracting the capacitive profile with a CRLH (composite right/left-handed) transmission line are presented. Using broadband techniques the input impedance in the LH and RH bands can be measured. The capacitance values along the line can be evaluated by applying extraction methods such as time domain reflectometry, perturbation theory or network synthesis. The areas of application of these methods is for sensing applications that range from transportation of materials in industrial processes to biomedical applications where the characteristics of an organic tissue is necessary.