Meandered Transmission Lines Research Articles

Highly sensitive RF sensor based on microstrip meander line for measuring microfluidics dielectric properties of alcohol–alcohol mixtures

Abstract In this paper, a radio frequency sensor for measuring microfluidics dielectric properties is designed based on microstrip meander line. The meander sensor replaces the straight transmission lines with meander transmission lines in the part of the half-wavelength path difference to improve the sensitivity of the sensor and reduce its size. According to the experimental results, the meander sensor based on the meander line has higher accuracy and a lower relative error than the straight sensor in measuring methanol–ethanol mixtures with different molar fractions. The relative error measured by the meander sensor after calibration with an adjustable cavity is less than 1%. It is easier to detect the very slight variation in dielectric properties brought about by microfluidics. The detection technique can be further applied for the accurate detection of dielectric properties of valuable biological samples, providing a more concise and convenient way.

Novel Meandered Line EBG Filters with Significant Size Reduction Using Sine Tapering

Tapering electromagnetic bandgap (EBG) structures is a common method in designing microstrip filters with different periodic structures. A novel technique for tapering EBG structures with the amplitude coefficients obtained from the sine function has been illustrated. This method deduces mellifluous coefficients that improves the performance with reasonable stopband width, preferable insertion loss level, and much-minimized passband ripples compared to similar designs with other tapering methods (e.g., binomial distribution, Chebyshev distribution, and conventional cosine tapering). It also offers tandem use of tapered EBG structures, leading to the novel meandered transmission line tandem design that significantly reduces the length of the filter; more than 40% is possible, compared to the uniform and conventional tapered designs. Size reduction on such a large scale will benefit the designers with the limited space issues.

Design of N-Way Wilkinson Power Dividers with New Input/Output Arrangements for Power-Halving Operations

In this paper, new single/double-layer N-way Wilkinson power dividers (WPDs) were designed by using slow-wave structures such as narrow-slit-loaded and meandered transmission lines. For size reduction, the slit-loaded and meandered lines were used instead of the quarter-wavelength transmission lines of a conventional WPD. Based on the proposed approaches, two-, four-, and eight-way power dividers were designed, simulated, and fabricated. The fabricated 2-, 4-, and 8-way circuits were measured at the center frequencies of 2.03, 1.77, and 1.73 GHz, which are in excellent agreement with the predicted ones. The meandered transmission lines were also used to design WPD types with novel input/output port arrangements. For this purpose, two three-way WPDs were located on both sides of the same board to have different power-splitting ratios at different inputs and outputs in order to provide alternative solutions for antenna arrays. Furthermore, a five-way dual-layer WPD was introduced by locating the meandered transmission lines into two layers. The most important advantage of the proposed 3- and 5-way WPDs is that they allowed the input power at the next output port to be halved, in the order of P/2, P/4, P/8, P/16, and P/16. All the designed power-halving WPDs were simulated, fabricated, and successfully tested.

Numerical simulation results of printed polarizers based on meander transmission lines

Numerical simulation results of printed polarizers based on meander transmission lines

Design of microstrip quint‐band lowpass–bandpass filters with flexible passband allocation

In this paper, newly proposed microstrip quint-band lowpass–bandpass filters are presented. The lowpass filter structure comprises a meandered transmission line and modified T-shaped resonators. Based on such an lowpass filter (LPF) structure, a quad-band λ/4 inductively-coupled dual-mode stub-loaded stepped impedance resonators BPF with one pair of a coupled I/O feeding line are parallelled on both sides of LPF to construct a quint-band lowpass–bandpass filter. By incorporating the parallel I/O coupled line and utilising multiple coupling paths, four bandpass bands can be fully controlled and designed independently. Specially, two distinct types of bandpass filters with different generating mechanisms are investigated and then combined to provide the quad-band responses. To validate the design concept, two types of quint-band lowpass–bandpass filters are designed, fabricated, and tested, where simulation results agree well with measurement results.

Wearable Spoof Surface Plasmon Polariton Transmission Line

In this work, we present a study of Spoof Surface Plasmon Polari-ton (SSPP) supported by a meandered Transmission Line (TL) dedicated to wireless body sensor network applications. First, dispersion curves evidence the existence of a surface wave propagation, called odd mode according to the symmetry of the magnetic field. This mode can be wirelessly excited with of a dipole antenna parallel-positioned above the meandered transmission line. Experimental part is validated with a SSPP TL fabricated on a Kapton substrate and compared with a wearable SSPP TL produced by embroidering a metallic yarn on a textile substrate. Second, transmission measurements for both SSPP TLs are also pre-sented and compared. The difference of performances achieved between involved technologies is explained by the conductivity value of the metallic yarn. Finally, the use of embroidered SSPP TL shows an improvement of the transmis-sion compared with the transmission in free space. This study is investigated in simulation and experiments by determining the dispersion curves and the transmission for two SSPP TLs.

Wireless Experimental Determination of Dispersion Curves of Spoof Surface Plasmon Polariton Modes Supported by a Transmission Line

Excitation of spoof surface plasmon polaritons (SSPPs) by means of a dipole antenna is considered to experimentally assess the dispersion curves of the two first modes guided by a meandered transmission line (TL). First, simulated dispersion curves bring out even and odd symmetries of the SSPP modes highlighted by magnetic field mappings. Then, a dipole antenna with vertical and horizontal polarization is proposed for generating the even and odd propagation modes by near‐field magnetic coupling, respectively. Experimental validation is carried out with a SSPP TL fabricated on a flexible substrate (Kapton). For each mode, experiments show a pass‐band feature of the transmission between two antennas coupled to the SSPP TL with ripples related to the presence of a standing wave. Finally, the dispersion curves are experimentally achieved using a de‐embedding method applied on the scattering parameters directly measured between antennas without the need of a mode conversion structure. Experimental results are favorably compared with the simulated transmission and dispersion curves.

Novel Chipless RFID High Resolution Crack Sensor Based on SWB Technology

A novel chipless RFID based structural health monitoring sensor is proposed in this paper. By using the time domain reflectometry (TDR) based technique, this device enables a wireless, low-cost and pervasive sensing system for detecting the presence of crack in a structure. The proposed sensor is designed on the Taconic TLX-0 substrate and it integrates a super wide band (SWB) antenna with a long transmission line. The SWB antenna covers a bandwidth of 2-20 GHz which offers extremely short time domain pulses. This eventually enables a high-resolution crack sensing scheme that results in higher accuracy and greater precision. A thorough analysis on the designed sensors with a straight and a meandered transmission line is carried out and a comparative study between the SWB and UWB technologies is performed to imply the superiority of the proposed technique. The experimental results from a fabricated prototype of the sensor validate the theoretical analysis.

A novel compact lowpass filter with sharp roll-off and wide stopband

AbstractIn this paper, a microstrip lowpass filter adopting two main resonators with steep transition band and wide rejection band has been introduced. The first main resonance cell consists of meandered transmission lines which are loaded by modified T-shaped patches. The second main resonator is composed of high-impedance lines loaded by polygon patches. To obtain a steep skirt performance, the first and second resonators have been combined. Moreover, employing eight high–low impedance folded stubs and two rectangular open-stubs as suppressing cells has resulted in improving the stopband features. To comprehend the frequency behavior of the employed resonators and also their combination, the formulas of the transmission coefficient, reflection coefficient, and the transmission zeros of their equivalent LC circuits have been extracted, separately. According to the measurement results, the −3 dB operating frequency of this filter is 1.65 GHz. Moreover, a relative stopband bandwidth equal to 166% with a corresponding attenuation level of 23 dB and a sharp roll-off rate (393.61 dB/GHz) have been achieved. In the passband region from DC to 1.632 GHz, the insertion loss and return loss are better than 0.0763 and 15.85 dB, respectively, proving an acceptable in-band performance. Finally, the implemented structure brings about a high figure-of-merit equal to 81 672.

Miniaturized dual‐band branch‐line coupler with enhanced bandwidth

AbstractIn this letter, a miniaturized hybrid dual‐band branch‐line coupler (BLC) with enhanced fractional bandwidths is proposed. Compact size and bandwidth enhancement are obtained using meandered transmission line sections with broken symmetry between cross‐coupling branches. The circuit is designed at a low numerical cost using surrogate‐assisted techniques. The optimized design features small size of only 0.25 λ g × 0.19 λ g (28% miniaturization with respect to conventional single‐band structure), as well as fractional bandwidths of 16% and 9% for 2.5 GHz and 5.4 GHz center frequencies, respectively. The proposed structure is compared against state‐of‐the‐art dual‐band couplers and validated experimentally.

A Novel Ultrawideband Transmitarray Design Using Tightly Coupled Dipole Elements

One of the key challenges in transmitarray (TA) designs is its narrow bandwidth. To overcome this limitation, this paper proposes a novel design of ultrawideband TA antenna based on tightly coupled dipole arrays (TCDAs). The array consists of $20 \times 10$ unit cells, and each unit cell is composed of a pair of short dipoles connected with a section of meandered transmission line. The size of each unit cell is 20 $\text {mm} \times 10$ mm, which is about $0.2\lambda \times 0.1\lambda $ , where $\lambda $ is the wavelength in free space at the lowest working frequency of the TA. By utilizing the strong coupling between adjacent units of the TA, the bandwidth of the TA is improved significantly. To verify the design concept, one prototype of the proposed TA is fabricated and measured. The prototype demonstrates good performance over a bandwidth of 104%, i.e., from 3.0 to 9.5 GHz, which is significantly wider than that of other TAs reported in the literature. Within the working band of the TA antenna, the radiation pattern is stable and no distortion or splitting of the main beam of the antenna is observed. This is the first time that the TA based on TCDA is reported.

Decoherence-Free Interaction between Giant Atoms in Waveguide Quantum Electrodynamics.

In quantum-optics experiments with both natural and artificial atoms, the atoms are usually small enough that they can be approximated as pointlike compared to the wavelength of the electromagnetic radiation with which they interact. However, superconducting qubits coupled to a meandering transmission line, or to surface acoustic waves, can realize "giant artificial atoms" that couple to a bosonic field at several points which are wavelengths apart. Here, we study setups with multiple giant atoms coupled at multiple points to a one-dimensional (1D) waveguide. We show that the giant atoms can be protected from decohering through the waveguide, but still have exchange interactions mediated by the waveguide. Unlike in decoherence-free subspaces, here the entire multiatom Hilbert space (2^{N} states for N atoms) is protected from decoherence. This is not possible with "small" atoms. We further show how this decoherence-free interaction can be designed in setups with multiple atoms to implement, e.g., a 1D chain of atoms with nearest-neighbor couplings or a collection of atoms with all-to-all connectivity. This may have important applications in quantum simulation and quantum computing.

A designing method for band‐reject filter with high selectivity and tunable bandwidth

AbstractHigh selectivity band‐reject filters are usually demanded in applications such as removing QAM signals of digital cable TV network and removing interference signals in communication systems. In this letter, a filter design method which employ discontinuous meandered transmission line and isolated board is proposed. The experimental results show that the transient bandwidth (between −3 and −20 dB) of our filters is less than 1 MHz. Besides, the rejecting bandwidth of our filters can be tuned to fulfill the requirements of different applications.

Performance Improvement of Microstrip LPF Based on Transfer Function Analysis

A high performance microstrip LPF with adjustable cut-off frequency and outstanding specifications is designed, analyzed, and implemented. The structure comprises a meandered transmission line and modified and improved T-shaped resonators. In order to describe the design theory, the transfer function based on an LC equivalent circuit is calculated to adjust the cut-off frequency and the location of the transmission zeros (TZs). The proposed LPF has a $-$ 3-dB cut-off frequency equal to 1.208 GHz and a narrow transition band of 0.188 GHz. The proposed LPF achieves a wide stopband with 14th harmonic suppression, insertion loss less than 0.4 dB, and low VSWR. Finally, the fabricated LPF reaches an extremely high figure-of-merit of 102182, which is considered as a significant achievement.

Millimeter‐wave miniaturized couplers integrated on BiCMOS technology

ABSTRACTIn this article, we present a new wideband hybrid coupler for millimeter‐wave applications realized in the BiCMOS9MW 130‐nm process from STMicroelectronics. The fabrication of two slightly different couplers demonstrates the wideband performance associated with miniaturized size, thanks to the use of meandered transmission lines and lumped capacitors. The best coupler provides a −10‐dB matching bandwidth of 42% with an insertion loss of 0.6 dB and a phase shift of 88° at 60 GHz. The amplitude imbalance and the phase imbalance stay, respectively, within ±1 dB and ±5° over 27 and 36%. These state‐of‐the‐art results are compared to recently published results obtained with comparable hybrid couplers. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:587–590, 2014

Dual band Trapezoidal antenna with Partial Ground and Meander line feed for GPS and WiMAX applications

ABSTRACTA dual band Trapezoidal antenna with Partial Ground and Meander line feed is proposed in this article. The antenna designed operates at 1.42–1.62 and 3.49–3.73 GHz simultaneously, which makes it suitable for 1.5 GHz global positioning system (GPS) and 3.5 GHz worldwide interoperability for microwave access (WiMAX) frequency bands, respectively. The antenna is fabricated on low‐cost FR‐4 substrate with 1.6 mm thickness. The proposed antenna consists of a trapezoidal‐shaped patch and a partial ground etched on bottom side of the strip. The antenna is fed through a meandered transmission line which reduces the overall antenna size. Moreover, the partial ground plane used facilitated the antenna radiation pattern to omnidirectional. The antenna is measured to observe the performance in comparison with simulated result. Gains of 1.7 and 3.4 dBi are recorded, with high gain especially at the second frequency band of the design. There is very good agreement between the simulation and measurement results. Hence, the antenna is suitable for GPS and WiMAX band applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:497–502, 2014

Compact microstrip lowpass filter with sharp roll‐off and ultra‐wide stop‐band

A compact microstrip lowpass filter (LPF) with sharp roll-off and ultra-wide stop-band bandwidth is presented. The structure consists of high-impedance meandered transmission lines loaded by triangular and polygonal resonant patches. The cutoff frequency of the proposed LPF is 2.44 GHz and the measured results show good performance such as sharp roll-off, good insertion loss and an ultra-wide stop-band from 2.53 to 35 GHz with the insertion-loss higher than 20 dB. There is a good agreement between the electromagnetic-simulation and measurement results.

Millimeter-wave miniaturized hybrid couplers integrated on advanced bicmos technology

In this article, we present the design and the measurement of two hybrid couplers for millimeter-wave applications realized in the BiCMOS9MW 130nm process (ST Microelectronics). The aim is to demonstrate several miniaturization possibilities of a conventional branchline coupler while maintaining a constant 90° phase shift and a low insertion loss over the full 57–66-GHz band. The first miniaturized coupler is composed of meandered transmission lines; the second is a quasi-lumped quadrature coupler with discrete capacitors. The performance of these circuits is compared with the most recent on-chip 60-GHz couplers. We especially demonstrate the possibility to achieve state-of-the-art performance while using miniaturization techniques. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2221–2223, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27079

Design of compact microstrip lowpass filter with ultra-wide stopband

A new microstrip lowpass filter with compact size and an ultra-wide stopband is proposed. To achieve compact size and ultra-wide band rejection, both triangular patch resonators and radial patch resonators are introduced in the filter. To reduce the circuit size of the filter further, meander transmission lines are also adopted in the design. A demonstration filter with 3 dB cutoff frequency at 1 GHz has been designed, fabricated and measured. Results indicate that the proposed filter can suppress the sixteenth harmonic response referred to a suppression degree of 15 dB. Furthermore, the proposed filter exhibits a small size of 0.111 λg×0.091 λg, where λg is the guided wavelength at 1 GHz.

Composite right/left-handed transmission line based on complementary single-split ring resonator pair and compact power dividers application using fractal geometry

A new resonant-type composite right/left-handed transmission line (CRLH TL) is proposed based on the combination of a complementary single-split ring resonator pair (CSSRRP) etched on the ground plane and a series gap embedded in the conductor strip of a microstrip line. The CSSRRP, which is composed of two identical complementary single-split ring resonators (CSSRR) with face-to-face splits, demonstrates negative permittivity. An equivalent circuit model is presented and studied in depth through the Bloch theory and finally validated by the simulated full-wave S-parameters. The balanced condition for novel CRLH TL is also derived. Moreover, the negative refractive index and backward wave propagation are confirmed by the effective constitutive parameters. It is proved that the zero-degree phase-shift CRLH TL exhibits a significantly lower resonant frequency by constructing the CSSRRP as Koch curves of different iteration order (K-CSSRRP). To demonstrate the applicability, two compact prototype device examples are provided, these being a three-way fork power divider and a four-way series power divider. The three-way divider achieves a 74.2% size reduction and displays comparable performance relative to its conventional counterpart, whereas the four-way divider obtains a 56% bandwidth enhancement and a 48% size reduction in comparison with a conventional one using a one-wavelength meandered transmission line.