Showing papers on "Stub (electronics) published in 2017"

Wearable Flexible Reconfigurable Antenna Integrated With Artificial Magnetic Conductor

Abstract: This letter presents a wearable flexible reconfigurable folded slot antenna. The antenna is composed of a folded slot and a stub where the reconfigurability is achieved by turning a p-i-n diode on and off , which alters the radiation characteristics of the stub. The operating frequency and polarization of the slot and stub are different. Hence, a polarization-dependent dual-band artificial magnetic conductor (AMC) surface is integrated with the antenna to improve its radiation performance and to reduce the specific absorption rate (SAR). The antenna is designed and fabricated on a flexible substrate, and its performance is measured for both flat and curved configurations. The measurements show an excellent agreement with the simulations. To examine its performance as a wearable antenna, it is measured on a human body. Simulations show that the SAR level is reduced when the AMC surface is used as an isolator. The proposed wearable antenna structure can be used for wireless body area network (WBAN) and Worldwide Interoperability for Microwave Access (WiMAX) body-worn wireless devices.

Simplified Numerical Modeling of Axially Loaded Circular Concrete-Filled Steel Stub Columns

Abstract: Behavior of concrete-filled steel tubular (CFST) columns can be predicted accurately using detailed finite-element (FE) modeling, but such models are tedious to build and impractical for fr...

CPW-Fed Dual-Band Dual-Sense Circularly Polarized Monopole Antenna

Abstract: A novel design of a dual-band and dual-sense circularly polarized coplanar-waveguide-fed monopole antenna with two rectangular parasitic elements and an I-shape grounded stub is presented here. The monopole consists of a vertical and a horizontal section. Lower band is obtained due to 90° phase difference between currents in the two orthogonal branches of the monopole. Upper band is obtained due to the I-shape stub. Parasitic elements help in input impedance matching. The dual-band and dual-sense antenna provides wide 10-dB impedance bandwidth of 71.63% at 2.82 GHz. The 3-dB axial-ratio bandwidths are 27.45% at 2.55 GHz (right-hand circular polarization) and 7.1% at 3.53 GHz (left-hand circular polarization).

Axial compressive behaviour of concrete-filled double-tube stub columns with stiffeners

Abstract: Concrete-filled double-tube (CFDT) columns, which are a new type of composite columns, have high fire resistance and the potential to be widely used in high-rise buildings. It is expected that the amount of steel used in a regular CFDT column will be relatively high due to the use of double tubes. To reduce the steel consumption, a thin-walled steel tube with longitudinal stiffeners may be adopted for the outer tube in a CFDT column. This paper studies the behaviour of concrete-filled stiffened double-tube (CFSDT) stub columns under axial compression. Tests on 12 CFSDT stub columns and two reference columns were carried out accordingly, and the test results confirm that the stiffened columns have high strength and good deformation capacity. A finite element model was developed to analyse the interaction between the steel tubes and concrete. Based on further parametric studies, a superposition model was proposed to predict the axial compressive strength of CFSDT stub columns.

High-Selectivity Tunable Balanced Bandpass Filter With Constant Absolute Bandwidth

Abstract: This brief presents a new and effective approach for designing a high-selectivity tunable balanced bandpass filter (BPF) with constant absolute bandwidth (ABW). The filter is composed of two open-loop resonators with a pair of symmetrically loaded varactor diodes to obtain tunable responses. The major design concept relies on choosing the particular position on the resonator for loading the varactor diodes. The desired variation slopes of the external quality factor and coupling coefficient can be easily obtained for realizing the constant ABW of the tunable BPF. Frequency-dependent source-load coupling between the feed lines are introduced for realizing two adaptive transmission zeros (TZs) on both sides of the tunable passband. Thus, during the frequency-tuning process, high selectivity of the proposed filter can be kept. Meanwhile, the common-mode suppression is optimized to an acceptable level in the frequency-agile range of the differential-mode passband by loading the stub and resistor in the series at the center of the resonator. For demonstration, a tunable balanced BPF with the constant ABW and two TZs is designed and implemented. The simulated and measured results are presented, showing good agreement.

A Planar Antenna With Voltage-Controlled Frequency Tuning Based on Few-Layer Graphene

Abstract: This letter presents a voltage-controlled tunable planar antenna based on few-layer graphene flakes. The antenna consists of a rectangular patch with a shorted microstrip stub connected to the radiating edge, and a graphene pad located at the input of the stub. The proposed design exploits the variation of the graphene resistance by an applied bias voltage. Without any bias voltage, the graphene pad behaves almost as an open circuit, not allowing any current passing and, thus, voiding the impact of the stub. Increasing the bias voltage reduces the graphene resistance, thus increasing the current passing through the pad into the stub. This results in the patch antenna radiating at a different frequency. A prototype operating at the frequency of 5 GHz has been designed and tested, demonstrating a frequency tunability larger than 10% with a limited gain degradation.

Ultra-compact dual-polarised UWB MIMO antenna with meandered feeding lines

Abstract: An ultra-compact dual-polarised ultra-wideband multi-input multi-output antenna made with a single-shared-radiating element and two meandered feeding lines are proposed. Miniaturisation is achieved by using a combination of techniques, including a resonant stub connected to the ground through which shorts the excessive coupled energy before it reaches the other port and minimises coupling, slots etched in the radiator that also help minimise mutual coupling, while the meandered lines allow to bring the antenna closer to the greatly reduce the overall size of the antenna. Slots etched in the radiator and the use of a stub connected to the ground through, help to minimise the mutual coupling. The formation of orthogonal surface currents provides the necessary dual polarisation. Simulated and measured results demonstrate the wideband impedance matching, low mutual coupling and low envelope correlation coefficient. This antenna has an extremely compact size (22 × 24.3 mm2, including the ground plane) that makes it an excellent candidate for portable and handheld devices.

A General T-Stub Circuit for Decoupling of Two Dual-Band Antennas

Abstract: This paper presents a novel technique for decoupling of two closely spaced dual-band antennas using T-stub circuits. A decoupling circuit consists of three T-stub elements, each of which provides the required phases and impedances in dual frequency bands independently. A set of general design formulas is derived for determining the electric parameters of required T-stubs. To validate the new decoupling technique, a pair of dual-band inverted-F antennas working in the 2.45- and 5.8-GHz bands and another pair of dual-band monopole antennas working in the 2.4- and 5.2-GHz bands with and without the decoupling circuit are designed, prototyped, and measured. The measured S-parameters correlate with the theoretical designed data very well. With the decoupling circuit, significant improvement in antenna efficiency and data throughput demonstrates that the technique is useful for wireless terminals, where dual-band multiple-input and multiple-output antennas are used.

A Multidirectional Pattern Reconfigurable Patch Antenna with CSRR on the Ground

Abstract: A pattern-reconfigurable patch antenna with nine beam directions based on the complementary split-ring resonator (CSRR) loaded ground is proposed. The antenna consists of a coaxial feed rectangular patch on the top layer and a ground plane loaded with four CSRRs on the bottom layer. Two p-i-n diodes are installed on the stub of every CSRR. By changing the states of the p-i-n diodes, the main radiation direction can be switched both in the E-plane and H-plane. The operation principle of the beam switching by loading CSRRs on the ground is discussed. The prototype is fabricated with p-i-n diodes and bias circuit. The measured common impedance bandwidth of |S 11 | less than -10 dB is from 2.42 to 2.48 GHz. The 3-dB beamwidth covers the elevation angles from 0° to more than 60° and full azimuth angles. The antenna has a compact size of 0.82 λ 0 × 0.78 λ 0 , which has the potential to be used in the array design.

Flat-band light dynamics in Stub photonic lattices.

Abstract: We experimentally study a Stub photonic lattice and excite their localized linear states originated from an isolated Flat Band at the center of the linear spectrum. By exciting these modes in different regions of the lattice, we observe that they do not diffract across the system and remain well trapped after propagating along the crystal. By using their wave nature, we are able to combine – in phase and out of phase – two neighbor states into a coherent superposition. These observations allow us to propose a novel setup for performing three different all-optical logical operations such as OR, AND, and XOR, positioning Flat Band systems as key setups to perform all-optical operations at any level of power.

Electromagnetically Induced Transparency and Refractive Index Sensing for a Plasmonic Waveguide with a Stub Coupled Ring Resonator

Abstract: A plasmonic refractive index sensor based on electromagnetically induced transparency (EIT) composed of a metal-insulator-metal (MIM) waveguide with stub resonators and a ring resonator is presented. The transmission properties and the refractive index sensitivity are numerically studied with the finite element method (FEM). The results revealed an EIT-like transmission spectrum with an asymmetric line profile and a refractive index sensitivity of 1057 nm/RIU are obtained. The coupled mode theory (CMT) based on transmission line theory is adopted to illustrate the EIT-like phenomenon. Multiple EIT-like peaks are observed in the transmission spectrum of the derived structures based on the MIM waveguide with stub resonator coupled ring resonator. To analyze the multiple EIT-like modes of the derived structures, the H z field distribution is calculated. In addition, the effect of the structural parameters on the EIT-like effect is also studied. These results provide a new method for the dynamic control of light in the nanoscale.

Dual-Band Defected Ground Structures Wireless Power Transfer System With Independent External and Inter-Resonator Coupling

Abstract: This brief proposes a design methodology based on the admittance ( ${J}$ -) inverters for a dual-band wireless power transfer (WPT) system that employs two cascaded circulars defected ground structure (DGS) resonators with different capacitive loading to guarantee distinct resonances. A single microstrip line excites the two DGSs, and when two DGS resonators are coupled back to back, it transforms to a dual band pass filter leading to WPT at both bands. Each of the DGS resonators has independent coupling. Thus, the realized ${J}$ -Inverters are designed independently. Also, we employ a single stub for the matching. This stub appears with a different length according to the operating frequency; hence, an independent external coupling is achieved at both frequencies. A compact size of 30 mm ${\times } \,\, 15$ mm is fabricated achieving a WPT efficiency of more than 71% at a power transfer distance of 16 mm for both bands (0.3 and 0.7 GHz).

A Microwave Microfluidic Sensor Based on a Dual-Mode Resonator for Dual-Sensing Applications.

Abstract: In this paper, we propose a novel microwave microfluidic sensor with dual-sensing capability. The sensor is based on a dual-mode resonator that consists of a folded microstrip line loaded with interdigital lines and a stub at the plane of symmetry. Due to the specific configuration, the resonator exhibits two entirely independent resonant modes, which allows simultaneous sensing of two fluids using a resonance shift method. The sensor is designed in a multilayer configuration with the proposed resonator and two separated microfluidic channels-one intertwined with the interdigital lines and the other positioned below the stub. The circuit has been fabricated using low-temperature co-fired ceramics technology and its performance was verified through the measurement of its responses for different fluids in the microfluidic channels. The results confirm the dual-sensing capability with zero mutual influence as well as good overall performance. Besides an excellent potential for dual-sensing applications, the proposed sensor is a good candidate for application in mixing fluids and cell counting.

Refractive Index Sensor Based on a Metal–Insulator–Metal Waveguide Coupled with a Symmetric Structure

Abstract: In this study, a new refractive index sensor based on a metal-insulator-metal waveguide coupled with a notched ring resonator and stub is designed. The finite element method is used to study the propagation characteristics of the sensor. According to the calculation results, the transmission spectrum exhibits a typical Fano resonance shape. The phenomenon of Fano resonance is caused by the coupling between the broadband spectrum and narrowband spectrum. In the design, the broadband spectrum signal is generated by the stub, while the narrowband spectrum signal is generated by the notched ring resonator. In addition, the structural parameters of the resonators and the structure filled with media of different refractive indices are varied to study the sensing properties. The maximum achieved sensitivity of the sensor reached 1071.4 nm/RIU. The results reveal potential applications of the coupled system in the field of sensors.

A Low-Profile Broadband 32-Slot Continuous Transverse Stub Array for Backhaul Applications in $E$ -Band

Abstract: A high-gain, broadband, and low-profile continuous transverse stub antenna array is presented in E-band. This array comprises 32 long slots excited in parallel by a uniform corporate parallel-plate-waveguide beamforming network combined to a pillbox coupler. The radiating slots and the corporate feed network are built in aluminum whereas the pillbox coupler and its focal source are fabricated in printed circuit board technology. Specific transitions have been designed to combine both fabrication technologies. The design, fabrication, and measurement results are detailed, and a simple design methodology is proposed. The antenna is well matched ( $S_{11} dB) between 71 and 86 GHz, and an excellent agreement is found between simulations and measurements, thus validating the proposed design. The antenna gain is higher than 29.3 dBi over the entire bandwidth, with a peak gain of 30.8 dBi at 82.25 GHz, and a beam having roughly the same half-power beamwidth in E- and H-planes. This antenna architecture is considered as an innovative solution for long-distance millimeter-waves telecommunication applications such as fifth-generation backhauling in E-band.

Behavior of steel-reinforced concrete-filled square steel tubular stub columns under axial loading

Abstract: The objectives of this paper is to investigate the mechanical behavior of steel reinforced concrete-filled square steel tubular (SRCFT) stub columns under axial loading through combined experimental and numerical studies. In total of six specimens are tested to investigate the effect of the concrete strength and steel ratio on the mechanical behavior of SRCFT stub columns. The ultimate bearing capacity, ductility, and confinement effects are discussed and clarified based on the experimental results. The inserted steel section can effectively prevent shear cracks in the core concrete from propagating quickly. The strength-weight-ratio of SRCFT stub column is larger than SCFT stub column. In addition, ABAQUS is used to establish the 3D finite element (FE) model and analyze the composite action of SRCFT stub columns under axial loading. Based on the experimental and numerical results, a simplified formula is proposed to estimate the ultimate bearing capacity of SRCFT stub columns using superposition method. The predicted results show satisfactory agreement with both experimental and FE results.

Beam-Scanning Continuous Transverse Stub Antenna Fed by a Ridged Waveguide Slot Array

Abstract: A continuous transverse stub (CTS) array antenna is presented for beam-scanning applications. Rotatable ridged waveguide slot array (RWSA) is used as a line source to feed a CTS array for the first time. The proposed RWSA has easy design, compact structure, light weight, and easy sidelobe control. The CTS array and RWSA can be designed and optimized separately. A good beam-scanning capability of ±30° is achieved by rotating the RWSA at almost the same angles, thus obtaining a fine beam-scanning resolution. The measured aperture efficiency exceeds 60% in the entire beam-scanning range. Therefore, the proposed antenna can be a good alternative for radar systems and satellite communication terminals, which require low cost and high gain.

A Passive-Impedance-Matching Technology to Achieve Automatic Current Sharing for a Multiphase Resonant Converter

Abstract: A passive-impedance-matching (PIM) technology is proposed to achieve automatic current sharing for multiphase resonant converters through matching the input impedance of each phase. The series inductors (or series capacitors) of each phase are connected in parallel to achieve a couple of virtual resistors including positive and negative resistors and variably series inductors (or capacitors). A virtual positive (or negative) resistor increases (or decreases) the input impedance of the respective phase, and the variably series inductors can also compensate the component tolerance such that the impedance of each phase is matched. The current-sharing performance of the common-inductor two-phase LLC resonant converter (as one example) is evaluated under the first-harmonic-approximation assumption. The virtual positive and negative resistors and variably virtual inductors are calculated. The proposed method can share the primary resonant current and the load current for all phases without any additional circuit and control strategy. The PIM technology is extended to other resonant converter topologies, including common-inductor or common-capacitor series-resonant converter, LCC, CLL resonant converter, etc. A 600-W 12-V common-inductor two-phase LLC resonant converter prototype is built to verify the feasibility and demonstrate advantages of PIM technology.

Impedance Matching Techniques for Microstrip Patch Antenna

Abstract: Objective: To present a concise and comprehensive summarization of various impedance matching techniques for microstrip patch antennas. Method: Designing an impedance matching network is a central issue for optimum performance in every part of RF systems like transceiver, amplifier and antenna to ensure maximum power transfer. Various design formulae to calculate the input impedance of patch antenna and techniques to design a matching network should be known to RF designer. Finding: In this paper various impedance matching techniques along with their design equations are presented that utilize quarter wave transformer, taper lines, open or short stubs and lumped elements etc. Methods to calculate the input impedance for various antenna structures like rectangular, circular and triangular patch antenna are described. Application: This paper concisely covers some of the existing techniques to design an impedance matching network that can be used to solve the impedance matching problem encountered during antenna design.

Design of Unequal Dual Band Gysel Power Divider With Isolation Bandwidth Improvement

Abstract: This letter presents a new design of an unequal dual band Gysel power divider (GPD) with isolation bandwidth (IW) improvement, which contains two grounded resistors for better power-handling capability (PHC), one resistor between output ports for enhancing the IW, an extension line at the input and a single stub line at the end for dual band operation, and ten branch line sections. Exact closed-form equations are derived for the proposed structure. For verification, the proposed structure is simulated, fabricated, and measured using microstrip lines. Simulation and measurement results show wide IW, while maintaining high PHC over the Wilkinson PD.

Novel Wideband Bandpass Filter with Dual Notched Bands Using Stub-Loaded Resonators

Abstract: In this letter, a novel wideband bandpass filter with dual notched bands using stub-loaded resonators is proposed. By using the signal interaction of two transmission paths, a wideband passband and two notched bands can be independently achieved and designed. By cascading two back-to-back vertical transitions, a six-pole wideband filter with equal ripple filtering response is synthetically analyzed. The dual notched bands are controlled by the even- and odd-mode resonant frequencies of the stub-loaded resonator. As a design example, the proposed wideband filter with dual notched bands is simulated and fabricated. The desired wideband filtering response is experimentally validated, and two notched bands are measured at 3.04 and 3.85 GHz, respectively.

A Wideband Contactless and Bondwire-Free MMIC to Waveguide Transition

Abstract: A contactless transition from a high-permittivity microstrip line ( $\epsilon _{r}=9.9$ ) to an air-filled waveguide (WG) has been impedance-matched over a large simulated relative bandwidth of 38% ( $W$ -band, 75–110 GHz). The transition couples the electromagnetic fields directly from the Monolithic Microwave Integrated Circuit (MMIC’s) microstrip line via an Substrate Integrated Waveguide and an off-chip stub section to a ridge WG section. The novel structure is low loss and suits pick-and-place assembly techniques of mm-wave MMICs inside metal WGs. The design process is detailed and manufacturing tolerances of the alumina prototype printed circuit board are discussed. The measured back-to-back structure retains an appreciable insertion loss smaller than 0.8 dB for a single transition and a fractional bandwidth of 28% (72–95 GHz) over which the return loss is greater than 10 dB.

Plasmonic waveguide with folded stubs for highly confined terahertz propagation and concentration.

Abstract: We proposed a novel planar terahertz (THz) plasmonic waveguide with folded stub arrays to achieve excellent terahertz propagation performance with tight field confinement and compact size based on the concept of spoof surface plasmon polaritons (spoof SPPs). It is found that the waveguide propagation characteristics can be directly manipulated by increasing the length of the folded stubs without increasing its lateral dimension, which exhibits much lower asymptotic frequency of the dispersion relation and even tighter terahertz field confinement than conventional plasmonic waveguides with rectangular stub arrays. Based on this waveguiding scheme, a terahertz concentrator with gradual step-length folded stubs is proposed to achieve high terahertz field enhancement, and an enhancement factor greater than 20 is demonstrated. This work offers a new perspective on very confined terahertz propagation and concentration, which may have promising potential applications in various integrated terahertz plasmonic circuits and devices, terahertz sensing and terahertz nonlinear optics.

Compact UWB mimo antenna with band‐notched characteristic

Abstract: A compact UWB–MIMO antenna with WLAN band notched characteristic is presented. UWB coverage is achieved with two closely spaced planar–monopole elements on the top side of the dielectric substrate with a truncated ground‐plane etched on the bottom side. Isolation between the antennas is achieved by creating a current path to decouple energy between the radiation elements using a T‐shaped ground stub. Notched frequency band between 5.15 and 5.85 GHz is achieved with a parasitic rectangular strip on the bottom side, which is connected to the radiating patch through a via hole. This approach yields a highly compact antenna design having dimensions of 22 × 29 × 0.8 mm3. Simulated and measured results confirm the antenna has an impedance bandwidth of 7.6 GHz from 3.0 to 10.6 GHz making it suitable for UWB MIMO systems.

Zero-power, long-range, ultra low-cost harmonic wireless sensors for massively distributed monitoring of cracked walls

Abstract: A novel zero-power wireless crack sensor based on the harmonic radar principle is presented. The tag, fabricated on a paper substrate by means of the copper adhesive tape technology, is targeted for a fundamental frequency f 0 =2.45 GHz (ISM band) and consists of a system of two nested annular slots, a frequency doubler and a stub behaving as a band-stop filter. In presence of a crack, the stub, placed at the input of the doubler, is torn off and an alarm is sent to the receiver. Such a system is suitable for scenarios which involve the detection of any crack increase in a massively distributed population of cracked wall sensors. A wireless experiment demonstrates an operating range of the sensor from 1 to 5 m for a transmitted power EIRP of 25 dBm.

A Compact Balanced-to-Balanced Filtering Gysel Power Divider Using $\lambda _{g}$ /2 Resonators and Short-Stub-Loaded Resonator

Abstract: In this letter, a compact balanced-to-balanced filtering power divider (FPD) is presented. It is composed of three half-wavelength resonators and a short-stub-loaded resonator (SSLR). Due to the intrinsic resonance characteristic of the half-wavelength resonator, the bandpass response and power dividing function for differential-mode signal are realized and the suppression for common-mode signal is also achieved. The SSLR is utilized as an extra isolation resonator to achieve high isolation between two output ports. A resister is also needed to load on the SSLR for adjusting its loaded quality factor $(Q_{e})$ . For the demonstration of the design method, an FPD operating at 2.405 GHz has been fabricated and measured. The measured results validate the design method.