bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miniaturization of logarithmic spiral antenna with modified Koch curve
Authors: Sharma Chetna , Vishwakarma Dinesh 
Published: August 2018

AbstractThis study proposes a unique methodology of reducing the footprint of logarithmic spiral antenna with the help of suitably scaled fractal known as modified Koch curve. In this process, first, the outer contour of the spiral arm is approximated with Fibonacci spiral which discretizes the former's geometry with a certain number of quarter circular sections. These sections are then superimposed with the iterations of modified Koch curve that leads to the miniaturization of the test antenna by 46% without compromising its spectral and radiation properties. The generalized mathematical approach has been developed to enable designing a compact logarithmic spiral antenna with an arbitrary growth factor. Finally, to validate the accuracy of proposed procedure, the prototypes having a selected growth rate have been fabricated and measured. The results such as reflection coefficient, impedance, gain, efficiency, radiation pattern, and axial ratio bandwidth of the first and second iterated modified Koch logarithmic spiral antenna are similar to the original logarithmic spiral operating in frequency range 2.00–18.30 GHz.
SOA‐based AOWC of 128QAM using Gaussian pulse shaping for transmission system with 227 Gbps
Authors: Li Guang , Li Jianqing , Chen Guojie , Huang Xuguang 
Published: August 2018

AbstractWe demonstrate an ultra‐high‐speed transmission system‐based, all‐optical wavelength conversion using Gaussian pulse shaping and 128 quadrature amplitude modulation. In this system, the modulated ultra‐high‐speed, photonic‐carrier signals with the modulation format of 128 quadrature amplitude modulation are coupled with the outputs of the double pump lasers, and amplified by nonlinear, all‐optical processing via a semiconductor optical amplifier. The transmission system with the wavelength conversion from 193.4 to 193.19 THz is then achieved. By the compensation of transmission impairments based on the digital signal processing algorithms, the single‐carrier signals with the converted wavelength of 193.19 THz are transmitted over the standard single‐mode fiber with the bit rate of 227 Gbps. In addition, the transmission performances influenced by the optical signal‐to‐noise ratio, injection current of the semiconductor optical amplifier, and the bandwidth of the Gaussian optical filter are analyzed. The relationship curves about bit error rate and error vector magnitude under different conditions are given, and the relationship between bit error rate and error vector magnitude is demonstrated.
A directional circularly polarized crossed‐dipole antenna with bandwidth enhancement
Authors: Guo Zifang , Zhao Zhiqin , Yang Yaohui , Ding Xiaoxiang 
Published: August 2018

AbstractA broadband circularly polarized antenna based on the crossed‐dipole structure is designed. The antenna consists of a pair of dual‐side printed crossed dipoles, a loop phase delay line, and a parasitic patch. By modifying the configuration of the dipoles and introducing a parasitic patch, a wide axial ratio (AR) bandwidth is obtained. A defected ground plane is designed, which has a significant improvement in extending the 3‐dB AR bandwidth and enhances the gain. The proposed prototype is manufactured and measured for validation. Measured results show that the antenna achieves both −10 dB impedance bandwidth and 3‐dB AR bandwidth of 68.6% (2.3–4.7 GHz). Moreover, the average gain of the antenna is about 8 dBi within the operating band, with a floating less than 2 dB.
Ku‐band gap waveguide filter design with improved out of band response
Authors: Mazinani Masood , Arezoomand Masoud , Pirhadi Abbas 
Published: August 2018

AbstractIn this paper, a Ku‐band filter was designed based on the Gap Waveguide (GW) technology with improved out‐of‐band response. After extracting an appropriate circuit model for the intended filter, different parts of it such as the resonators, couplers between resonators as well as input and output couplers to resonators were implemented using the GW structures. After the filter was designed in the operating frequency band, its out‐of‐band behavior, which occurs due to the excitation of higher modes, was examined and the characteristics of the filter were improved in out‐of‐operating frequency band. Finally, the filter was fabricated and a comparison of the simulation results with the measurement results confirmed the validity of the designed method.
High‐frequency dielectric analysis of carbon nanofibers from pan precursor at different pyrolysis temperatures
Authors: Munajat N. A. , Nurfaizey A. H. , Bahar A. A. M. , You K. Y. , Fadzullah S. H. S. M. , Omar G. 
Published: August 2018

AbstractCarbon nanofibers (CNF) produced from pyrolysis of electrospun polyacrylonitrile (PAN) precursor has received a great amount of attention due to their promising potentials. However, there are limited studies on the electrical properties of the CNF, especially at high‐frequency range. In this study, CNF from PAN precursor were produced by electrospinning technique. Characterizations of the nanofibers were carried out in terms of physical, dielectric, and chemical properties. The stabilization of nanofibers took place at 240°C whilst carbonization process took place at temperatures of 800°C, 1000°C, and 1200°C, respectively. In terms of physical properties, the color of the nanofiber webs changed from white to brown and black, after stabilization and carbonization process accompanied by significant reduction in average fiber diameter. Dielectric analysis of the nanofibers was obtained by measuring the wave propagation characteristics at frequency range of 1 GHz to 10 GHz. Higher dielectric constants of the material were observed for fibers processed at higher carbonization temperatures. Good conductivity was also observed with loss tangent value that is higher than 1. The results were correlated with FTIR transmittance results, indicating greater amount of carbon are present in the nanofiber material. From the findings, the unique behavior of the nanofibers makes it practically potential for sensor applications. Explorations of future research in this area are to be sought.
A comprehensive model for phase noise characteristics of an optoelectronic oscillator
Authors: Guo Jiao Jiao , Jin Xiang Dong , Zhu Yan Hong , Jin Xiao Feng , Chi Hao , Zheng Shilie , Zhang Xian Min 
Published: August 2018

AbstractA comprehensive model for phase noise characteristics of an optoelectronic oscillator (OEO) is presented. The phase noise distributions of an OEO especially near the carrier are explained comprehensively, combining the Yao‐Maleki model and Leeson model. An experiment is carried on for verification of the OEO's phase noise distribution. Based on the comprehensive model, the phase noise distribution of an OEO can be predictably designed.
Analysis of amplification in a fiber ring resonator with a fabry‐perot cavity
Authors: Magalhães Regina , Silva Susana , Frazão Orlando 
Published: August 2018

AbstractThe placement of an Erbium‐doped Fiber Amplifier and a Fabry‐Perot cavity inside a fiber ring resonator can generate a sinusoidal modulation in the optical signal obtained. The characterization of this behavior is achieved by changing the length of the Fabry‐Perot cavity, which acts as a sensing device. A theoretical model of the optical signal modulation obtained with such configuration is also presented.
A new filtering monopole antenna with wideband harmonic suppression
Authors: Wei Zichun , Zhai Huiqing , Zhou Xiangyu , Zheng Licheng 
Published: August 2018

AbstractIn this letter, a new integrated filtering monopole antenna with wideband harmonic suppression is presented. In the design of the proposed antenna, a compact multiple harmonic suppression low pass filter is introduced and its stopband characteristic from 5 to 20 GHz is well integrated with the common monopole antenna. The final integrated filtering antenna can work from 2.88 to 4.02 GHz, and its wideband harmonic suppression successfully achieves 5.8 times of the central working frequency. The good performances of the present filtering antenna are shown by the simulated results and measured results, which could be a good candidate for the 5G anti‐interference wireless terminal communication system.
A novel low profile antenna array with high isolation performance
Authors: Xi Lei , Zhai Huiqing , Li Long 
Published: August 2018

AbstractIn this letter, a novel low profile antenna array with high isolation performance is proposed. The antenna realizes a low profile of 0.1λ0 by using artificial magnetic conductor (AMC) as the reflector. The antennas are compactly arranged on the AMC surface with a space of 0.5λ0. Two rows of metal through holes are placed in the middle of the AMC to prevent surface wave from propagating, thereby the coupling between the antennas is reduced. Simultaneously, isolation between the antennas is increased by more than 10 dB. And the prototype of the antenna array is fabricated and measured. Finally, the low profile antenna array with high isolation performance is verified by the simulated results and the measured results.
A compact coplanar waveguide Wilkinson power divider based on signal traces and adjacent grounds width modulation
Authors: Al Shamaileh Khair , Dib Nihad , Abushamleh Said 
Published: August 2018

AbstractWe propose a miniaturized coplanar waveguide Wilkinson power divider by varying the widths of the signal traces and grounds. Traces are expressed in terms of a truncated Fourier series. Simulated/measured input–output ports matching and isolation are below −15 dB, and the transmission parameters are −3 ± 0.1 dB at the design frequency.
Thermally enhanced GaN hybrid‐IC power amplifier using embedded IC process in a copper sheet
Authors: Yoon Tae‐Woong , Kim Dong‐Su , Yook Jong‐Min 
Published: August 2018

AbstractThis article introduces new packaging that improves the heat dissipation of RF power devices. Typically, power devices are mounted on a printed circuit board, in which the heat dissipation is made only through the bottom area of a device. The heat dissipation of the proposed structure is made through the bottom and side areas. As a result, proposed technology provides 30% improved heat dissipation in the RF GaN power amplifier. A copper sheet having a high thermal conductivity of around 400 W/mK is used as a core material to embed the power device. The measured results show that the drain efficiency of the fabricated X‐band power amplifier (PA) improved by about 13% in the proposed package structure.
A novel ultra‐wideband monopole antenna for ground penetrating radar application
Authors: Hendevari Maryam Samadpour , Pourziad Ali , Nikmehr Saeid 
Published: August 2018

AbstractIn this article, a novel monopole antenna for the ground penetrating radar applications is proposed. The antenna is a monopole bowtie with two slots and a defected ground plane, in order to improve the bandwidth. The proposed antenna shows a great bandwidth from 3.9 to 18 GHz which makes it to be an ultra‐wideband antenna. The overall size of the antenna is 14 × 22 × 1.6 mm3 on the FR4 substrate. Also, a prototype of the proposed antenna is fabricated. The measurement and simulation results are in good agreement.
Parallel ring‐line rat‐race circuit with very loose coupling
Authors: Kawai T. , Matsuda T. , Sakakura M. , Enokihara A. 
Published: August 2018

AbstractThis article describes rat‐race circuits (RRCs) in which a pair of ring‐lines have parallel lines of ±180‐degree difference for electrical length to realize the RRC with very loose coupling such as −10 dB or less. The proposed RRCs with parallel ring‐lines realize a coupling factor of −10 dB and −20 dB by using moderate characteristic impedance lines with a view point of fabrication tolerance for general PCB technologies. We confirm the validity of this circuit construction and design method using a commercial electromagnetic simulator and decide the circuit pattern for fabrication at a center frequency of 2.45 GHz. The fabricated RRCs with parallel ring‐lines realize the desired coupling factors and in‐/out‐of‐phase outputs, and the measurement results of scattering parameters for −10 dB and −20 dB RRCs are in good agreement with the simulation results.
A novel 1‐to‐3 feeding network with radiation contribution
Authors: Hou Yuefeng , Zhang Zhijun , Feng Zhenghe 
Published: August 2018

AbstractThe feeding network is an essential part of the series‐fed microstrip array antenna. It needs additional space on the substrate or even extra layer of the substrate. However, the traditional feeding network has no contribution to the gain, which will result in an unnecessary waste of space. In this letter, a novel 1‐to‐3 feeding network combining with radiated patches is presented. To the best of the authors’ knowledge, the feeding network with radiation contribution is reported for the first time. The modified feeding network can feed antenna and radiate energy at the same time. To verify the design strategy, a series‐fed microstrip array antenna with the proposed radiated feeding network is designed. Compared with the series‐fed microstrip array antenna with traditional feeding network, a 15.3% higher gain is obtained by the proposed antenna. Finally, a prototype of the proposed antenna is fabricated and tested. Measured results show that the antenna works in a band from 9.41 to 10.18 GHz. The measured peak gain is 19.75 dBi at 10 GHz. A good agreement between simulated and measured results is achieved.
A compact CPW‐fed tapered monopole triple‐band antenna for WLAN/WiMAX application
Authors: Pandit Vivek Kumar , Harish A. R. 
Published: August 2018

AbstractA coplanar waveguide (CPW)‐fed very compact triple‐band, low profile planar monopole antenna for WLAN/WiMAX application is proposed. The proposed antenna consists of two V‐shaped and two open ended inverted L‐shaped slots in a tapered monopole attached to a tapered CPW feed line. The antenna operates in the 2.4/5.2/5.5‐GHz WLAN and 3.5/5.5‐GHz WiMAX bands and has very compact size of 18 × 22 × 0.5 mm3 (0.135λ0 × 0.165λ0 × 0.0037λ0). In addition, the proposed antenna has omnidirectional radiation pattern, high reflection outside the desired bands, and stable gain over each band. The antenna has been fabricated and tested and the measured results agree well with the simulation results.
A 5 GHz narrow‐beam leaky‐wave antenna using binomially distributed slot based substrate integrated waveguide
Authors: Farooq Memoona , Khan Muhammad U. , Cheema Hammad M. 
Published: August 2018

AbstractThis article presents a planar substrate integrated waveguide based leaky wave antenna (LWA) with narrow beamwidth, high directivity, and low side lobe levels (SLL). Through first‐time use of binomially distributed slots, a significant decrease in SLL along with a small form factor is achieved. Designed on a Rogers 5880 substrate, the proposed design occupies 250 × 45 mm2 exhibiting a beamwidth of 11.3° and sidelobe level less than −10 dB at 5.6 GHz. In comparison with conventional LWA with uniform slots, a 63% size reduction is also achieved.
Highly selective bandpass filter using substrate integrated waveguide technology for FMCW radar application
Authors: Vala Alpesh , Patel Amit 
Published: August 2018

AbstractA bandpass filter using substrate integrated waveguide technology is proposed in this paper for ISM band frequency (5.7–5.9 GHz) application. Metallic inductive posts are used for the realization of the filter. The proposed structure provides pass band from the frequency range of 5.72 GHz to 5.84 GHz with the insertion loss of 0.7 dB and return loss more than 25 dB. Frequency tuning is carried out from the frequency range of 5.65 GHz to 6.06 GHz with the variation of pass band bandwidth from 88 MHz to 222 MHz. All the simulations are carried out by high frequency structure simulator based on FEM method software. Proposed bandpass filter is fabricated and measured result indicates better performance. It will be utilized in the system developed at CSRTC for the suppression of higher order harmonics in frequency modulated continuous wave radar at the frequency from 5.725 GHz to 5.875 GHz.
On the computation and comparison of specific absorption rate (SAR) in a skin tissue using analytical and numerical methods
Authors: Asif Sajid M. , Iftikhar Adnan , Maile Keith , Ewert Daniel L. , Braaten Benjamin D. 
Published: August 2018

AbstractSpecific absorption rate (SAR) is a measure of safety and a requirement for portable radio frequency devices which are regulated mainly by the standards recommended by the Institute of Electrical and Electronics Engineers (IEEE) and International Commission on Non‐Ionizing Radiation Protection (ICNIRP). Accurate approximation of SAR is therefore important for safety as well as for compliance purposes. This article presents the analytical representation and derivation of the SAR from the basics of electromagnetic theory, Maxwell Equations, and law of conservation of energy in electromagnetic theory. It is shown, analytically, that for a time harmonic electromagnetic wave propagating in a homogeneous lossy medium having permittivity ϵ, permeability µ, and conductivity σ, the time rate change of electric and magnetic energy densities at steady state inside a given volume is zero. It is also shown that at the steady state, the net power flowing through a volume, bounded by a surface is equal to the power dissipated in that volume. Furthermore, this work demonstrates that at the steady state, SAR can be represented in terms of power density or in terms of power dissipated in the given volume. Moreover, calculation of SAR for a 1 mm × 1 mm × 0.01 m box having the dielectric properties of human skin was performed using the derived formulas and then compared with the numerical results, obtained using a full wave 3D simulation tool, HFSS. A good agreement was found between the analytical and numerical results.
U‐shaped stacked structure monolithic transformer for efficiency improvement
Authors: Kang Sungyoon , Kim Minchul , Kim Junghyun 
Published: August 2018

AbstractThis article presents a novel monolithic transformer (TF) structure, which is designed to improve TF efficiency by enhancing the quality factor of the metal trace. When the number of thick metal layers is limited in semiconductor technology, it is necessary to use thin metals that have lower quality factors to form the TF coil, which degrades TF efficiency. To overcome this limitation, supplementary walls of metal and a via are connected along both sides of the thin metal to form a U‐shaped metal trace, which in turn improves the quality factor and TF efficiency. The proposed structure does not require additional metal layers, other than the metal layers used in the TF configuration. Thus, the proposed structure is widely applicable to all semiconductor technologies, including those that provide only a small number of metal layers. To assess and validate this proposed structure, we fabricated a set of TFs including conventional structures using gallium arsenide (GaAs) technology, which is the most widely used technology in mobile power amplifier (PA) fabrication. The proposed structure was successfully demonstrated to effectively improve the TF efficiency by as much as 8.6% and 6.5% in comparison to a conventional planar structure and a stacked structure, respectively.
A linearity‐improved multi‐band envelope tracking Tx power amplifier under antenna mismatch for mobile applications
Authors: Ji Donghyeon , Jeon Jooyoung , Kim Junghyun 
Published: August 2018

AbstractA linearity‐improved multi‐band envelope tracking power amplifier (ET PA) with digital predistortion (DPD) under antenna mismatch is introduced based on the advanced mismatch detection and correction technique. An advanced tunable output matching network (TOMN) is utilized to correct the mismatch and to reconfigure the operating band, simultaneously. An advanced phase shifter and an operating algorithm are newly proposed to detect mismatch on the multi‐band PA and are realized as a compact integrated circuit (IC), facilitating self‐contained operation without external control. The mismatch detector and RF switches for the TOMN were integrated into a single IC using silicon on insulator (SOI) CMOS, which was integrated with a 2‐μm InGaP/GaAs HBT PA monolithic microwave integrated circuit (MMIC) into a single module. With long‐term evolution (LTE) signal, the fabricated ET PA demonstrates a linearity improvement of 2–2.4 dB under 2.5:1 voltage standing wave ratio.
Novel slot‐coupled broadband waveguide junction for orthomode transducer using mirrored semi‐profiled section
Authors: Pandya Jigar M. , Sood Khagindra , Pujara Dhaval 
Published: August 2018

AbstractThis article proposes the waveguide junction for an orthomode transducer (OMT) with ≈35% realized bandwidth in waveguide slot‐coupled configuration employing a profiled taper/branching region. A wideband impedance match is achieved using a new mirror image concept while constructing the profile from a specified mathematical function. Numerical simulation and experimental verification were carried out for the proposed OMT and good agreements are achieved. This modified configuration provides broader bandwidth compared to the conventional waveguide slot‐coupled OMT's (% bandwidth ≈27%) reported till date. The proposed waveguide junction can be used in multi‐frequency, multi‐band high‐performance antennas and feed systems.
Liquid metamaterial based radome design
Authors: Patel Shobhit K. , Kosta Y.P. , Charola Shreyas 
Published: August 2018

AbstractWe present liquid metamaterial based radome design. Radome is a layer used to protect antenna from weather disturbances. The addition of this layer reduces the gain of antenna. Our aim here is to improve this gain. Liquid metamaterial based radome presented in the manuscript improves the gain performance of antenna. The designed liquid metamaterial radome structure is applied to patch antenna for its performance observation. Antenna design with and without liquid metamaterial radome is tested in this manuscript. The design results in the form of return loss, bandwidth and gain are measured and compared. From the comparison, it is evident that the design with liquid metamaterial radome improves the gain of the antenna. The designed antenna with metamaterial liquid radome is applicable in narrowband sensitive radar antenna applications.
A miniaturized triple band monopole antenna with a coupled branch strip for bandwidth enhancement for IoT applications
Authors: Chung Ming‐An 
Published: August 2018

AbstractA miniaturized monopole antenna with multiband operations for LTE, WWAN, WiMAX, and WLAN applications is presented. The antenna consists of multibranch strips and is fabricated on both sides of the FR4 substrate, which has a compact size of 10(L) ×10(W) ×0.8(T) mm3 to be embedded inside the Internet of Things (IoT) device as an internal antenna. Three operating bands covering 2.3–2.69, 3.4–3.7, and 5.15–5.85 GHz for the LTE, WWAN, WiMAX (2.3/2.5/3.5 GHz), and WLAN (2.4 GHz) systems are achieved with good radiation efficiencies. The proposed antenna can be embedded in the IoT device for the LTE, WWAN, WiMAX, and WLAN applications. The proposed antenna has advantages of sided structure, easy fabrication, low cost, and multiband operation. Also, the impedance matching performance of 3 resonant modes for the antenna can be adjusted flexibly. This makes the proposed antenna design suitable for practical applications. Details of the design process and the experimental results of the constructed antenna are presented.