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Showing papers on "Stub (electronics) published in 2018"


Patent
03 Jan 2018
TL;DR: In this article, the authors describe a launcher that includes a hollow waveguide that guides a first electromagnetic wave conveying data from a transmitting device, and a dielectric stub coupler that supports a coupling of the second guided wave mode for propagation along an outer surface of the transmission medium.
Abstract: Aspects of the subject disclosure may include, for example, a launcher that includes a hollow waveguide that guides a first electromagnetic wave conveying data from a transmitting device. A dielectric stub coupler receives the first electromagnetic wave from the hollow waveguide to form a second electromagnetic wave that propagates along a portion of the dielectric stub coupler adjacent to a transmission medium, wherein second electromagnetic wave propagates along the dielectric stub coupler via a first guided wave mode and a second guided wave mode, and wherein the portion has a length that supports a coupling of the second guided wave mode for propagation along an outer surface of the transmission medium.

241 citations


Journal ArticleDOI
TL;DR: In this article, a broadband dual-polarized filtering dipole antenna for base station application is presented, which consists of four parts: main radiator, feeding baluns, reflector, and two parasitic loops.
Abstract: This paper presents a broadband dual-polarized filtering dipole antenna for base-station application, which has a compact size of 50 $\text {mm} \times 50\,\,\text {mm} \times 31.8$ mm. The antenna consists of four parts: main radiator, feeding baluns, reflector, and two parasitic loops. Without using complex filtering circuits, the dual-polarized dipole antenna realizes satisfactory filtering performance and enhanced bandwidth by employing only two parasitic loops. Two specific radiation nulls are thus generated and individually controlled by the two parasitic loops. To further improve the upper stopband selectivity and bandwidth, a simple open-ended stub is added to the arms of the dipole. As a result, the bandwidth can be tuned from 7.4% to 47.6%, and the realized gain is decreased dramatically from 8.6 dBi at 2.7 GHz (in-band) to −10 dBi at 2.9 GHz (out-of-band). For demonstration, a broadband dual-polarized dipole antenna is implemented. Measured results show that the proposed antenna has more than 34 dB port isolation over 48.7% (1.66–2.73 GHz) impendence bandwidth (VSWR < 1.5). The measured in-band gain is about 8.15 dBi with stable 3 dB beamwidth 65.4°±2.4° in the horizontal plane, whereas the out-of-band radiation suppression is more than 17 dB.

108 citations


Journal ArticleDOI
TL;DR: A novel coplanar waveguide-fed rectenna with high efficiency is proposed and implemented in this paper for 2.45-GHz Bluetooth/ wireless local area network applications.
Abstract: A novel coplanar waveguide-fed rectenna with high efficiency is proposed and implemented in this paper for 2.45-GHz Bluetooth/ wireless local area network applications. The antenna has compact dimensions of 18 mm $\times \,\, 30$ mm, which is simulated and manufactured using a low-cost FR4 substrate with a thickness of 1.6 mm. A tuning stub technique with rectangular slots is used for better impedance matching and enhancing the impedance bandwidth of the antenna with a peak gain of 5.6 dB. The proposed novel antenna for RF energy harvesting applications exhibits dipolelike radiation pattern in $H$ -plane and omnidirectional pattern in $E$ -plane with improved radiation efficiency. Single-stage Cockcroft–Walton rectifier with L-shaped impedance-matching network is designed in advance design system and fabricated on FR4 substrate. The dc output of the rectenna is measured as 3.24 V with a load resistance of 5 $\text{k}\Omega $ . A simulated peak conversion efficiency of 75.5% is attained, whereas the measured one is observed to be 68% with an input signal power of 5 dBm at 2.45 GHz.

97 citations


Journal ArticleDOI
TL;DR: In this paper, a miniaturized circularly polarized (CP) implantable antenna is designed at 915 ISM band for far-field wireless power transmission, which has the smallest size and maintains good radiation performance, compared with previous CP implantable antennas.
Abstract: A wireless power link with circular polarization is studied in this letter for far-field wireless power transmission. First, a miniaturized circularly polarized (CP) implantable antenna is designed at 915 ISM band. The proposed antenna features a good miniaturization with the dimensions of 11 × 11 × 1.27 mm3 by employing the stub loading and capacitive coupling among the stubs. It has the smallest size and maintains good radiation performance, compared with previous CP implantable antennas. The simulated impedance bandwidth covers from 889 to 924 MHz for | S 11| less than −10 dB, and the axial-ratio (AR) bandwidth (AR < 3 dB) is from 901 to 912 MHz. The results show that the antenna is suitable for far-field wireless power transmission. The proposed wireless power link achieves higher converted dc power compared to previous similar letter.

81 citations


Journal ArticleDOI
TL;DR: In this article, a compact coplanar waveguide (CPW) fed ultra-wide band (UWB) multi input multi output (MIMO) antenna is proposed, which consists of two antiparallel hexagonal ring monopole elements.
Abstract: In this paper, a compact coplanar waveguide (CPW) fed ultra-wide band (UWB) multi input multi output (MIMO) antenna is proposed. The antenna consists of two antiparallel hexagonal ring monopole elements. Circular arcs shaped grounded stubs are used to enhance the isolation, both the arcs are connected through stub to make common ground. Tapering of the slots of CPW feed line at feed point, and grounded slots are introduced for impedance matching over UWB. The proposed antenna is fabricated and impedance bandwidth, isolation, radiation pattern, and gain are measured. Moreover, envelop correlation coefficient (ECC) results are given. Proposed antenna structure operates in the frequency range 3–12 GHz with a fractional bandwidth of 120% keeping isolation better than 15 dB. The antenna has a compact size of 45 × 25 mm2.

76 citations


Journal ArticleDOI
TL;DR: In this article, a three-order filtering stacked patch antenna with a center frequency of 2.3 GHz and a fractional bandwidth of 15.2% is fabricated, and two independently controllable radiation nulls are located at 1.97 and 2.61 GHz.
Abstract: This communication presents a filtering antenna with high selectivity using multiple coupling path from source/load to resonators. The high selectivity of the filtering antenna’s boresight gain response is achieved by a novel coupling scheme, which induces additional coupling between source/load and nonadjacent resonators to construct cross coupling paths. Thanks to the extra cross-coupling paths, the filtering antenna can generate a maximum of N radiation nulls with N resonators. Besides, a resonator using a combination of open-ended stub and short-ended stub is adopted to construct this novel coupling scheme more easily. For demonstration, a three-order filtering stacked patch antenna with a center frequency of 2.3 GHz and a fractional bandwidth of 15.2% is fabricated. Two independently controllable radiation nulls are located at 1.97 and 2.61 GHz. Unidirectional radiation patterns have been achieved with cross polarization lower than −20 dB and back lobes lower than −18 dB.

76 citations


Journal ArticleDOI
TL;DR: In this paper, an experimental and theoretical study of CFRP-confined concrete-filled circular steel tube (CFT) stub columns is presented, which aims at investigating the effects of different numbers of layers and concrete strengths on the mechanical performance of CFT stub columns.
Abstract: This paper presents an experimental and theoretical study of CFRP-confined concrete-filled circular steel tube (CFT) stub columns, which aims at investigating the effects of different numbers of CFRP layers and concrete strengths on the mechanical performance of CFRP-confined CFT stub columns. Based on continuum mechanics, a mechanical model of concentric cylinder consisting of CFRP, circular steel tube and concrete core under concentric loading was established and the corresponding elasto-plastic methods were obtained through a FORTRAN program. The influence of the number of CFRP layers on the ultimatecapacity, ductility and confinement effect of the steel tube on the core concrete wasdiscussed and identified. Finally,based on the limit equilibrium and elasto-plastic methods, a simplified formula for the ultimatecapacity of CFRP-confined CFT stub columns was proposed. Good agreement of the ultimate capacity was found between the elasto-plastic methods and the proposed formula, with the maximum discrepancy less than 12%.

76 citations


Journal ArticleDOI
TL;DR: The proposed MIMO/diversity antenna can be a good candidate for portable UWB applications and when installed on a printed circuit board with a standard size, with USB connector, and device housing and various other types of housing show good performance.
Abstract: This paper presents a bandwidth enhanced, compact, multiple-input–multiple-output (MIMO) antenna with high isolation for modern wireless ultrawideband (UWB) applications. The proposed antenna consists of two simple eye-shaped slot radiators, and in order to enhance isolation, the proposed antenna uses a rectangular-shaped ground plane with an extruded T-shaped stub. The antenna characteristics such as the S-parameters, realized gain, surface current distributions, and radiation patterns are investigated. Furthermore, the diversity performance of MIMO antenna in terms of envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and multiplexing efficiency is also studied. The designed antenna shows the impedance bandwidth of 17.2 GHz (from 2.8 to 20 GHz) with a compact size of $18\times 36$ mm2. The antenna possesses a low mutual coupling of less than −20 dB over the operating band, the ECC and the DG are less than 0.02 and greater than 9.95 dB, respectively. The prototype is fabricated and tested for impedance and radiation characteristics. The proposed antenna when installed on a printed circuit board with a standard size, with USB connector, and device housing and various other types of housing show good performance. The proposed MIMO/diversity antenna can be a good candidate for portable UWB applications.

75 citations


Journal ArticleDOI
TL;DR: In this article, a single-polarized filtering dielectric resonator antenna (DRA) with high selectivity is investigated, where the DRA is fed by hybrid microstrip line/conformal strip, excited in its fundamental TE$1\delta 1}^{y} $ mode.
Abstract: A compact single-polarized filtering dielectric resonator (DR) antenna (DRA) with high selectivity is investigated. The DRA is fed by hybrid microstrip line/conformal strip, excited in its fundamental TE $_{1\delta 1}^{y} $ mode. Owing to different loading effects of the microstrip stub and conformal strip, the resonance frequency of TE $_{1\delta 1}^{y}$ mode excited by the two feed lines is slightly different. Such stepping resonances yield a wide bandwidth of 21.9% and a very flat gain of 5.1 dBi. The hybrid-feeding scheme also establishes a cross-coupled structure in the DRA, which introduces two radiation nulls right near the band edges. A compact wideband filtering DRA (FDRA) with quasi-elliptic bandpass response is, therefore, obtained without requiring any specific filtering circuit. This single-polarized design is also modified to realize a dual-polarized FDRA by adding another orthogonal port with the same feeding scheme. To reduce mutual coupling between the two ports, the microstrip stubs are folded to L shape, and four additional metal posts are inserted into the DR. As a result, the isolation is improved by 14 dB, from 7.2 to 21.2 dB.

73 citations


Journal ArticleDOI
TL;DR: This work is partially supported by the Innovation Programme under grant agreement H2020-MSCA-ITN-2016SECRET-722424 and the financialsupport from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.
Abstract: The paper presents a technique to enhance the isolation between adjacent radiating elements which is common in densely packed antenna arrays. Such antennas provide frequency beam-scanning capability needed in Multiple-Input Multiple-Output (MIMO) systems and Synthetic Aperture Radars (SARs). The method proposed here uses a metamaterial decoupling slab (MTM-DS), which is located between radiating elements, to suppress mutual-coupling between the elements that would otherwise degrade the antenna efficiency and performance in both the transmit and receive mode. The proposed MTM-DS consists of mirror imaged E-shaped slits engraved on a microstrip patch with inductive stub. Measured results confirm over 9–11 GHz with no MTM-DS the average isolation (S12) is -27 dB; however, with MTM-DS the average isolation improves to -38 dB. With this technique the separation between the radiating element can be reduced to 0.66λo, where λ0 is free space wavelength at 10 GHz. In addition, with this technique there is 15% improvement in operating bandwidth. At frequencies of high impedance match of 9.95 GHz and 10.63 GHz the gain is 4.52 dBi and 5.40 dBi, respectively. Furthermore, the technique eliminates poor front-to-back ratio encountered in other decoupling methods. MTM-DS is also relatively simple to implement. Assuming adequate space is available between adjacent radiators the MTM-DS can be fixed retrospectively on existing antenna arrays, which makes the proposed method versatile.

71 citations


Journal ArticleDOI
TL;DR: In this paper, a CPW fed metamaterial inspired quadband circularly polarized antenna is presented, which consists of defected ground structure with a radiating stub, which is at opposite side of the feedline.
Abstract: A CPW fed metamaterial inspired Quadband circularly polarized antenna is presented in this article. The proposed antenna consists of defected ground structure with a radiating stub, which is at opposite side of the feedline. A waveguide mode of analysis is carried out for split ring resonator (SRR) and complimentary split ring resonator (CSRR) to enhance the properties of metamaterials. The proposed antenna analysis is taken iteration wise and used FR-4 Material as the substrate material with Ɛr = 4.4 and analysed using ANSYS electromagnetic desktop. The designed antenna projecting the peak gain of 4.8 dB and it is working in the application bands of WLAN/ISM/Bluetooth at 2.4 GHz, 5.8 GHz and 3.35 WiMAX band, X-band downlink satellite communication system (7.25–7.75 GHz) and ITU band (8–8.5 GHz) with fractional bandwidth of about 70%. Proposed antenna exhibits circular polarization at 2.39–2.55 GHz, 3.05–3.1 GHz, 4–5 GHz and 6.3–6.64 GHz respectively. To know the signal integrity of the antenna, time domain analysis is carried out for identical antennas in two conditions (face to face and side by side) with the help of CST microwave studio. The designed antenna showing excellent correlation in measurements with respect to simulation results.

Journal ArticleDOI
TL;DR: In this article, the axial static mechanical behavior of circular carbon fiber reinforced polymer (CFRP)-steel composite tubed concrete stub columns was investigated, including an experimental study and a theoretical analysis.

Journal ArticleDOI
TL;DR: To address the out-of-band characteristic drawback that existed in most of the previous UWB antenna, a parallel coupled band-pass filter with stepped impedance transformation and defected ground structure is incorporated in the feedline of the antenna to achieve sharp rejection at the edges of the UWB band.
Abstract: In this paper, a miniaturized fully inkjet-printed flexible multiple-input-multiple-output (MIMO) antenna for ultrawideband (UWB) application is proposed, occupying a compact size of $22\times 31\times 0125$ mm3 In the proposed antenna, two half-planar radiators are introduced to minimize the antenna size Moreover, a modified T-shaped stub is employed on the ground plane to improve the impedance performance In addition, a slot is etched on this modified T-shaped ground stub to further enhance the isolation By doing so, the proposed antenna can operate from 29 to more than 12 GHz with the mutual coupling less than −15 dB Furthermore, to address the out-of-band characteristic drawback that existed in most of the previous UWB antenna, a parallel coupled band-pass filter with stepped impedance transformation and defected ground structure is incorporated in the feedline of the antenna to achieve sharp rejection at the edges of the UWB band The measurements indicate that the proposed filter-antenna can cover from 343 to 101 GHz, with the envelope correlation coefficient below 03 and the channel capacity loss below 04 bit/s/Hz, which ensures its good MIMO performance

Journal ArticleDOI
TL;DR: The theoretical foundations of the engineered balanced filter approach, along with guidelines to design the differential-mode transfer function and to attain optimum in-band common-mode power-attenuation characteristics, are expounded.
Abstract: A new type of RF $/$ microwave differential-mode planar multiband bandpass filters (BPFs) are presented. Each symmetrical half of the proposed balanced filtering architecture is composed of the in-series cascade of $K$ $N$ -stub-loaded cells through $K-1$ inter-connection transmission-line segments to synthesize a differential-mode transfer function with $N$ $K$ th-order passbands. Additional features of this balanced multiband BPF topology are as follows: 1) generation of transmission zeros at both sides of all differential-mode passbands; 2) high common-mode power-rejection levels within the differential-mode passband ranges; 3) scalability to any number of arbitrary-order differential-mode transmission bands; and 4) lack of electromagnetic couplings in its physical structure. The theoretical foundations of the engineered balanced filter approach, along with guidelines to design the differential-mode transfer function and to attain optimum in-band common-mode power-attenuation characteristics, are expounded. Furthermore, for experimental-demonstration purposes, a third-order triple-band microstrip prototype with differential-mode passbands that are located within the range 1.4–3 GHz is manufactured and characterized.

Journal ArticleDOI
TL;DR: In this article, a rectangular bracket-shape parasitic strip is placed at the open end of the straight microstrip line to excite the fundamental horizontal and vertical components of the circular polarization (CP).
Abstract: This letter presents a novel and simple feeding technique for exciting orthogonal components in a wide-slot antenna. In this technique, a rectangular bracket-shape parasitic strip is placed at the open end of the straight microstrip line to excite the fundamental horizontal and vertical components of the circular polarization (CP). The proposed technique—when employed in conjunction with the asymmetrical geometry of coplanar waveguide and a protruded stub from the ground plane—permits for maintaining axial ratio (AR) below 3 dB within a wide range in the C-band as well as a compact footprint of the antenna. All geometry parameters of the antenna are adjusted through rigorous EM-driven optimization to obtain the best performance in terms of footprint, impedance matching, and AR bandwidth (ARBW). The size of the proposed antenna is only 27 mm × 28.8 mm. The structure features a 62% impedance bandwidth (3.6–6.85 GHz) and ARBW of approximately 49% (3.6–5.93 GHz) with the average realized gain of 3.3 dB within the CP operating band. Numerical results are validated experimentally. A close agreement between simulation and measurement results has been observed.

Journal ArticleDOI
TL;DR: In this paper, the failure modes, composite behaviors and load-deformation histories of axially loaded special-shaped CFST stub columns are similar to those of SHS/RHS specimens.
Abstract: Special-shaped CFST columns are becoming increasingly attractive as alternative solutions to engineering design. Three-dimensional FE models are developed and verified against experimental results in terms of failure modes, load-deformation curves and ultimate loads, where circular, triangular, Fan-shaped, D-shaped, 1/4 circular and semi-circular sections are considered. In light of the FE simulations, the composite actions between the special-shaped steel tubes and concrete cores have been investigated through load-deformation and interaction stress-deformation histories. Possible parameters affecting specimens loading behaviors have been studied. The studies generally show that the failure modes, composite behaviors and load-deformation histories of the axially loaded special-shaped CFST stub columns are similar to those of SHS/RHS specimens.

Journal ArticleDOI
TL;DR: In this article, a compact plasmonic waveguide-coupled resonator system, which consists of a metal-insulator-metal (MIM) waveguide with a double stub side-colloupled to a ring cavity, is designed and numerically investigated using finite element method (FEM).

Journal ArticleDOI
TL;DR: A nanoscale structure which comprises metal-insulator-metal (MIM) waveguide, stub resonator, and hexagonal resonator is proposed to realize plasmon-induced transparency (PIT) response as mentioned in this paper.
Abstract: A nanoscale structure which comprises metal-insulator-metal (MIM) waveguide, stub resonator, and hexagonal resonator is proposed to realize plasmon-induced transparency (PIT) response. The characteristics of the device are numerically investigated with different geometrical parameters. Benefitting from the narrow transparency window and long coupling length between two resonators, the proposed devices are able to act as a nanosensor for refractive index (RI) sensing with figure-of-merit (FOM) of 178 and 140 RIU−1 near RI of 1 and 1.33, respectively. Furthermore, the FOM can be further improved by employing symmetric structure.

Journal ArticleDOI
TL;DR: In this paper, a tri-band patch antenna utilizing the TM10 mode together with modified TM20 and TM30 modes of a single patch is proposed in this communication, where asymmetrically loading a stub on one radiating edge of the patch and cutting a rectangular slot offset from the other one, resulting in broadside radiation for all the first three modes.
Abstract: A tri-band patch antenna utilizing the TM10 mode together with modified TM20 and TM30 modes of a single patch is proposed in this communication. Through asymmetrically loading a stub on one radiating edge of the patch and cutting a rectangular slot offset from the other one, the current distributions of the TM20 and TM30 modes are perturbed, resulting in broadside radiation for all the first three modes of a single patch. Each operational frequency can be effectively controlled through varying the dimensions of the patch, slot, and loading stub. Good impedance matching is achieved simultaneously in three operational bands through aperture coupling. A prototype is designed, fabricated, and measured for validation. Based on this tri-band antenna, a new tri-band filtering antenna is further developed, showing good selectivity and broadside radiation characteristic.

Journal ArticleDOI
Yanyan Shi1, Jianwei Jing1, Fan Yue1, Lan Yang1, Yan Li1, Meng Wang1 
TL;DR: A novel compact broadband rectifying antenna (rectenna) is presented for ambient radio frequency (RF) energy harvesting and a single stub matching network is investigated for impedance matching and the RF to DC conversion efficiency is improved at low input power.
Abstract: In this paper, a novel compact broadband rectifying antenna (rectenna) is presented for ambient radio frequency (RF) energy harvesting. Slot antennas with excellent bandwidth and matching characteristic are designed by etching fractal geometries with different iteration order on a radiation patch. A rectifier with a single stub matching network is investigated for impedance matching and the RF to DC conversion efficiency is improved at low input power. Simulation and the experiments have been carried out to evaluate the performance of antenna and rectifier respectively. A good match is observed between the simulated and measured results. The experimental results show that antenna features a broad bandwidth from 2.15 GHz to 2.9 GHz and the maximum conversion efficiency of rectifier is up to 64% at 0 dBm. The highest conversion efficiency of rectenna is 62% and the maximum output voltage is 1.5 V at the input power of 0 dBm.

Journal ArticleDOI
TL;DR: In this article, an electrically small printed monopole antenna is described with a fractional bandwidth of 185% (115 MHz to 2.90 GHz) for return-loss better than 10 dB, peak gain and radiation efficiency at 1.45 GHz of 2.35 dBi and 78.8%, respectively.
Abstract: Empirical results of an electrically small printed monopole antenna are described with a fractional bandwidth of 185% (115 MHz to 2.90 GHz) for return-loss better than 10 dB, peak gain and radiation efficiency at 1.45 GHz of 2.35 dBi and 78.8%, respectively. The antenna geometry can be approximated to a back-to-back triangular shaped patch structure that is excited through a common feed-line with a meander-line T-shape divider. The truncated ground-plane includes a central stub located underneath the feed-line. The impedance bandwidth of the antenna is enhanced with the inclusion of meander-line slots in the patch and four double split-ring resonators on the underside of the radiating patches. The antenna radiates approximately omni-directionally to provide coverage over a large part of very high frequency, the whole of ultrahigh frequency, the whole of L-band and some parts of S-band. The antenna has dimensions of 48.32 × 43.72 × 0.8 mm 3 , which is corresponding to the electrical size of 0.235 λ 0 × 0.211 λ 0 × 0.003 λ 0 , where λ 0 is the free-space wavelength at 1.45 GHz. The proposed low-profile low-cost antenna is suitable for application in wideband wireless communications systems.

Journal ArticleDOI
TL;DR: In this paper, a folded patch, which is centrally fed by a coplanar feedline, is proposed for designing a miniature UHF tag antenna for mounting on metal surfaces, which can achieve a maximum read distance of 10.7 m at the effective isotropic radiated power of 4 W.
Abstract: A folded patch, which is centrally fed by a coplanar feedline, is proposed for designing a miniature UHF tag antenna for mounting on metal surfaces. The tag is designed using a flexible polyethylene terephthalate substrate with a very compact size of 25 $\text {mm} \times 40\,\,\text {mm} \times 3$ mm ( $0.0767\lambda \times 0.123\lambda \times 0.0092\lambda$ ). Conjugate match is attainable between the antenna and the microchip and it is able to achieve a maximum read distance of 10.7 m at the effective isotropic radiated power of 4 W. In the design, two notches have been incorporated with an inductive stub for tuning of the tag’s resonance over a larger frequency range. Also, a simple equivalent circuit has been derived to characterize the impedance of the tag antenna. The resonant frequency of the proposed tag antenna is found to be insensitive to various sizes of the backing metal object, which is a very desirable feature for tag design. The proposed tag can achieve a read distance of greater than 10 m when placed on metal. It is able to be read beyond 5 m when it is placed on dielectrics with permittivity in the range of 1–5.8.

Journal ArticleDOI
TL;DR: A new quadruple-mode stepped-impedance square ring loaded resonator (SI-SRLR) is proposed, and a high-performance dual-band differential bandpass filter (BPF) is developed.
Abstract: In this paper, a new quadruple-mode stepped-impedance square ring loaded resonator (SI-SRLR) is proposed, and a high-performance dual-band differential bandpass filter (BPF) is developed. Resonant characteristics of the SI-SRLR are investigated by the even-/odd-mode method and simulation techniques. Two differential-modes (DMs) of the SI-SRLR are used to form the dual differential passbands. The admittance ratio $K$ of the SI-SRLR is chosen appropriately to prevent the common-mode (CM) interference with DM operations. Moreover, an open-circuited stub is added to enhance the CM suppression, while a source-load coupling is introduced to produce multiple transmission zeros and improve significantly the frequency selectivity of DM passbands. Finally, a dual-band differential BPF is designed, fabricated, and measured. Good agreement between the simulated and measured results verifies well the proposed structure and design method.

Journal ArticleDOI
TL;DR: In this article, the compressive behavior of cold-formed high-strength steel (HSS) stub columns has been investigated and the nominal 0.2% proof stresses of the high-streng...
Abstract: This paper presents the numerical investigation of the compressive behavior of cold-formed high-strength steel (HSS) tubular stub columns. The nominal 0.2% proof stresses of the high-streng...

Journal ArticleDOI
TL;DR: In this paper, a dual-wideband, dual-sense, circularly polarized (CP), square slot antenna with the simple structure is presented in this communication, and the measured 10 dB return loss bandwidth is 111% (1.82-6.36 GHz).
Abstract: A novel compact dual-wideband, dual-sense, circularly polarized (CP), square slot antenna with the simple structure is presented in this communication. The right-hand circular polarization in the +z-direction for the lower frequency is mainly realized by an inverted L-shaped strip, and the left-hand circular polarization in the +z-direction for the upper frequency is mainly achieved by an offset feed structure. A parasitic matching stub is helpful to improve the input impedance matching. The overall dimension of the prototype is only $50 \times 50 \times 1~\text{mm}^{3}$ . An optimized antenna is fabricated and measured. The measured 10 dB return loss bandwidth is 111% (1.82–6.36 GHz). Its measured 3 dB axial-ratio bandwidths in the broadside direction are 55% (1.91–3.36 GHz) at lower band and 29.3% (4.78–6.41 GHz) at upper band, which can fully cover all the wireless local area network and wireless fidelity bands. What is more, this antenna has stable antenna gain and good radiation patterns within these two CP bands.

Journal ArticleDOI
TL;DR: In this article, a band notched ultra wideband (UWB) antenna is presented as a good prospect for multiple-input multiple-output (MIMO)/diversity application.
Abstract: A band notched ultra-wideband (UWB) antenna is presented in this article as a good prospect for multiple-input multiple-output (MIMO)/diversity application. The proposed MIMO antenna is constituted of two modified rectangle-shaped patch antenna elements. A stepped stub is extended from the modified ground plane as a decoupling element between the radiators to realize a good isolation level between them. A band rejection response is obtained by connecting an open resonant stub to each of the radiators. The simulated prototype is fabricated and tested for verification. Results reveal that the proposed prototype provides a 10 dB return loss bandwidth from 3.08 to 10.98 GHz with band notch characteristics from 4.98 to 5.96 GHz, and a good port isolation level (S21 ≤ 20). Diversity performances are ensured in terms of total active reflection coefficient, envelope correlation coefficient (<0.013 except notch band), diversity gain (≈9.51 dB), mean effective gain ratio (≈1), and channel capacity loss (≤0.35 bps/HZ except notch band). It evidences that the presented band notched UWB antenna can be a good prospective for MIMO/diversity applications.

Journal ArticleDOI
TL;DR: This brief presents a novel design of a dual-band equal split Wilkinson power divider that is based around a single coupled line section as core and uses stub-based port matching networks at each of the ports for achieving perfect isolation.
Abstract: This brief presents a novel design of a dual-band equal split Wilkinson power divider. It is based around a single coupled line section as core and uses stub-based port matching networks at each of the ports. It then incorporates only one isolation resistor, which is independent of frequency-ratio, for achieving perfect isolation. Closed form design equations are developed for the general analysis of the power divider and design case studies are provided to evaluate the proposed design. The developed prototypes for frequency-ratios of 2 and 7 show a good agreement between the electromagnetic simulated and measured results and thus validate the reported theory.

Journal ArticleDOI
TL;DR: In this paper, a conformal circularly polarized (CP) antenna was designed for ingestible wireless capsule endoscope (WCE) systems at industrial, scientific, and medical (ISM) band (2.4-2.48 GHz), which consists of a rectangular loop, an asymmetric U-shaped strip, and a protruding L-shaped stub printed on the top of the dielectric substrate.
Abstract: A conformal circularly polarized (CP) capsule antenna, designed for ingestible wireless capsule endoscope (WCE) systems at industrial, scientific, and medical (ISM) band (2.4–2.48 GHz), is presented. The antenna consists of a rectangular loop, an asymmetric U-shaped strip, and a protruding L-shaped stub printed on the top of the dielectric substrate. The CP wave is generated by the corner-fed U-shaped strip protruding into the rectangular slot. Further, by adjusting the size of the U-shaped strip and the L-shaped stub, the 3 dB axial-ratio (AR) band can be fully covered by the 10 dB impedance band. The simulated 10 dB impedance bandwidth (BW) and 3 dB ARBW are 31.58% and 13.11%, respectively. The simulated results show that the overlapped impedance BW and ARBW are from 2.28 to 2.6 GHz, which completely covers the 2.4 GHz ISM band. The measured 10 dB impedance BW is 39.21%. Finally, the radiation performance, safety consideration, and link budget of the antenna are examined and characterized. Owing to the broad overlapped impedance BW and ARBW, the minimized in-capsule foot print, and ease of fabrication, the designed antenna is a capable candidate for a WCE system.

Journal ArticleDOI
TL;DR: In this article, a simple technique to extend the aperture of planar composite right/left-handed (CRLH) metamaterial antennas with minimal impact on the antenna's dimensions is presented.
Abstract: This paper presents a simple technique to extend the aperture of planar composite right/left-handed (CRLH) metamaterial antennas with minimal impact on the antenna’s dimensions Unlike most CRLH antenna structures the proposed antenna is via-free The proposed antenna is shown to operate over a wideband from UHF to C-band with good radiation characteristics The antenna configuration consists of a vertically stacked CRLH unit-cells comprising of a patch and meandered lines, where the patch is engraved with an S-shaped slot The design uses minimal ground plane area The meander line inductance is grounded using CPW ground which eliminates conventional CRLH TL metallic via into ground plane The antenna is feed through a coplanar waveguide (CPW) match stub that is electromagnetically coupled to the unit cells Antenna dimensions are 175×3215×16 mm3, which corresponds to 0204λ_0×0375λ_0×0018λ_0 where free-space wavelength (λ_0) is 35GHz Parametric study enabled the optimization of the antenna performance in terms of impedance bandwidth, radiation gain and radiation efficiency Measured results confirm the antenna can operate from 850 MHz to 790 GHz, which is equivalent to a fractional bandwidth of 16114% The antenna has a maximum gain and radiation efficiency of 512 dBi and ~80%, respectively, at 35GHz

Journal ArticleDOI
TL;DR: A novel guided-wave resonator that supports multiple bands of electromagnetically induced transparency (EIT) with a Q-factor of 147 and an effective group refractive index of 530 is reported.
Abstract: We report a novel guided-wave resonator that supports multiple bands of electromagnetically induced transparency (EIT). The platform for the spatial and spectral interference is obtained by a microstrip transmission line loaded with proximity-coupled open-circuited stubs. We show experimentally that with two microstrip open stubs, a complete destructive interference takes place leading to a single EIT band with near-unity transmission efficiency. More interestingly, the addition of a third stub results in a supplementary EIT band with a Q-factor of 147 and an effective group refractive index of 530. With the open-stub configuration, the EIT phase response can be dynamically controlled by varying the capacitance between the adjacent stubs without breaking the transmission path of the underlying electromagnetic waves. Therefore, the proposed structure is well suited for buffering and tunable phase modulation applications. Since the proposed structures are compact and fully planar, we anticipate seamless integration with low-profile high frequency electronics.