bluuebunny/crossref_metadata_2025_split huggingface dataset:
Model analysis of coupled‐mode leaky‐wave antenna for forward and backward frequency scanning
Authors: Kandwal Abhishek , Zhang Qingfeng , Das R. , Tang Xiaolan , Louis L.W. 
Published: April 2018

AbstractThis article proposes model analysis of a microstrip leaky‐wave antenna for forward and backward scanning. Mode coupling and dual scan concept is introduced in this article with an inverted V‐section leaky‐wave antenna. The proposed design concept has been implemented on microstrip planar structure. An inverted V‐section has been therefore implemented which resulted in frequency scanning in forward and backward directions in the right‐hand (RH) region. The phenomenon has been observed within same frequency bandwidth of leaky‐wave region which is normally difficult to see in conventional leaky‐wave antennas. The article has also provided a circuit model analysis and design implementation explained by mode coupling theory. The proposed dual scanning leaky‐wave antenna (DSLWA) design is providing a wide impedance bandwidth in the Ku‐band and K‐band with high gain, reduced side lobe levels and high radiation efficiency.
Multistub multimode resonating structure for microwave multiband band‐pass filtering applications
Authors: Pandit Nidhi , Pathak Nagendra Prasad 
Published: April 2018

AbstractThis article proposes a design, analysis, and characterization of multistub resonator with its multimode characteristics for band‐pass filtering applications. First, the principle of resonating structure is explained with related mathematical explanations. Next, the proposed multimode structure is introduced with simple technique to analyze resonating frequency behavior by related mathematics. Through mathematical analysis, it has been presented that the number of resonating frequency and their position can be individually controlled by structural parameter. As a result, the proposed resonating structure can be utilized to design different microstrip band‐pass filters (BPFs). For validating the concept, an ultra wide band (UWB) BPF with −3 dB impedance bandwidth of 4.6 GHz (1.9–6.5 GHz) and a dual band BPF with −3 dB impedance bandwidth of approximately 1.5 GHz (2.7–4.3 GHz) for the first band and around 2.1 GHz (6.2–8.3 GHz) for the second band; have been implemented on Neltec substrate with dielectric constant 3.38, thickness 1.52 mm, and loss tangent 0.0016 and characterized on Keysight vector network analyzer N9918A. All the measured and simulated results are in good agreement with each other.
A butterfly‐based direct solver using hierarchical LU factorization for Poggio‐Miller‐Chang‐Harrington‐Wu‐Tsai equations
Authors: Guo Han , Liu Yang , Hu Jun , Michielssen Eric 
Published: April 2018

AbstractA butterfly‐based hierarchical LU factorization scheme for solving the PMCHWT equations for analyzing scattering from homogenous dielectric objects is presented. The proposed solver judiciously re‐orders the discretized integral operator and butterfly‐compresses blocks in the operator and its LU factors. The observed memory and CPU complexities scale as O(N log2 N) and O(N1.5 log N), respectively. The proposed solver is applied to the analyses of scattering several large‐scale dielectric objects.
A 40‐GHz hybrid class‐AB/class‐BCMOSVCO with a current‐combining transformer
Authors: Oh Juntaek , Jang Jingyu , Hong Songcheol 
Published: April 2018

AbstractA 40‐GHz hybrid class‐AB/class‐B CMOS VCO with a current‐combining transformer (CCT) using a 65‐nm RF CMOS process is presented. The hybrid class‐AB/class‐B configuration is adapted to two cross‐coupled pairs to lower the power consumption while maintaining the phase noise performance. As a simple coupling network between two cross‐coupled pairs with different bias conditions, the CCT performs the roles of a high Q‐factor resonator, a large impedance transformer, and a buffer without additional circuitry. The VCO operates at 38.15–40 GHz with power consumption in the range of 11–13 mW. The measured phase noise at a 1‐MHz offset from the 40 GHz carrier is −117.1 dBc/Hz with a 1.0 V supply voltage. The proposed power oscillator achieves an FOMT value of −191.3 dBc/Hz.
A 55‐W high efficiency unbalanced three‐stage Doherty power amplifiers for various output power back‐offs
Authors: Kim Ji‐Yeon , Kang Yunho , Kim Jong‐Heon 
Published: April 2018

AbstractHigh efficiency unbalanced three‐stage Doherty power amplifiers (DPA) for input signals with various peak to average power ratios (PAPR) are presented. The amplifier uses three GaN devices of equal size. The output power back‐off (OPBO) at the efficiency peak of the amplifier can be extended and reduced according to the input signals with various PAPR. This is achieved by adjusting the impedances of the λ/4 impedance transformers at the individual amplifier output stages in the three‐stage DPA without the use of additional circuitries and by changing the impedance matching circuit at the input stages of the amplifiers. The current of the individual amplifiers in the three‐stage DPA is calculated according to the PAPR of the input signals. The impedances of the λ/4 impedance transformers are determined by the current ratio for the main, first peaking, and second peaking amplifiers and are implemented by microstrip lines. 55 W unbalanced three‐stage DPAs for extended and reduced OPBO are designed and fabricated to be operated at the frequency of 1810 MHz.
Gain enhancement of a printed leaf shaped UWB antenna using dual FSS layers and experimental study for ground coupling GPR applications
Authors: Kundu Surajit , Chatterjee Ayan , Jana Sanjay Kumar , Parui Susanta Kumar 
Published: April 2018

AbstractA printed leaf shaped compact (40 mm × 30 mm × 0.8 mm) UWB antenna added with dual frequency selective surfaces (FSS) of dimension 44 mm × 44 mm × 1.6 mm is proposed. The FSS layers having 4 × 4 array in each can provide maximum gain of 8.7 dBi and gain enhancement by 2–4.5 dBi in the antenna bandwidth of 3–14.64 GHz. The proposed design also ensures maximum radiation in the broadside direction with average radiation efficiency of 85%. The antenna bandwidth and group delay responses were measured in close proximity of soil test bed for varying test bed thicknesses. Relative bandwidth of more than 114% with non‐varying group delay response ensure the ability of proposed antenna to work for ground coupling ground penetrating radar applications.
A high frequency ratio quadri‐band frequency independently tunable antenna with spurious‐mode suppression
Authors: Li Peng Kai , You Chang Jiang , Yu Hong Fang , Cheng Yu Jian , Yang Yuan Wang , Deng Jian Hua 
Published: April 2018

AbstractA quadri‐band frequency independently tunable patch antenna with high frequency ratio is proposed in this article. It is realized by nesting two rectangular patches and two U‐shaped patches together separated with gaps. Each patch is resonating at one band. U‐shaped patches are utilized to suppress the spurious‐mode resonances when designing antenna with high frequency ratio. Two parallel varactors are embedded on each patch to tune its resonant frequency. Measured results demonstrate the quadri‐band antenna has tunable ranges of 0.75–0.97, 1.87–2.11, 2.37–2.63, and 3.36–3.72 GHz, respectively, with a high frequency ratio of 5, low spurious‐mode resonances, comparatively high gains of 2–8 dBi and efficiencies of 30–80%.
Design of optical leaky wave antenna with circular and diamond Si perturbations for enhancing its performance
Authors: Shah Karan H. , Sonagara Japit S. , Patel Shobhit K. , Argyropoulos Christos 
Published: April 2018

AbstractIn this manuscript a design of silicon on insulator (SOI)‐based dielectric (silicon nitride) Optical Leaky Wave Antenna loaded with periodic circular and diamond shape semiconductor (Si) perturbation is proposed. This optical antenna is excited at one end of dielectric waveguide. The proposed design is also compared with the existing design and the results are obtained which shows that proposed design is more efficient than the existing one. The design results in form of transmission coefficient and reflection coefficient are compared. The efficiency is increased by introducing circular and diamond shape perturbation in the waveguide. The designed Optical Leaky Wave Antenna will be applicable in optical switching and optical imaging.
Investigation on the surface flashover of high gain SI‐GaAs PCSS
Authors: Ji Weili , Shi Wei , Ma Cheng , Cao Juncheng 
Published: April 2018

AbstractThe GaAs photoconductive semiconductor switch (PCSS) is generally recognized currently as a leading power electronic device for its unique advantages. A major limitation of PCSS has been its surprisingly low voltage threshold for the surface flashover found when PCSS works at the high gain mode. In this paper, the surface flashover of high gain PCSS is studied by experiments. We propose that the non‐uniform distribution of the surface field that resulted from the photo‐activated charge domain (PACD) and the gas desorption is the key cause of such reducing of the SF field. SF6 ambient dielectric is efficient in increasing the surface field, and the experiment results show that the PCSS we developed could resist a voltage as high as 20 kV/cm when the ambient dielectric is 3 atmospheric SF6. This conclusion has the practical application of significance to improve the performance of the high gain PCSS, which is severely limited by the premature breakdown effects.
Slot‐loaded patches with a switching mechanism to extend the scanning range of a phased array subject to scan blindness
Authors: Ayissi Manga Aurélien , Gillard Raphaël , Loison Renaud , Le Roy‐Naneix Isabelle , Renard Christian 
Published: April 2018

AbstractThis article presents a novel solution to extend the scanning range of a cavity‐backed stacked‐patch phased array whose performances are limited by scan blindness. Two main aspects are investigated. The first section is a thorough description of the scan blindness mechanism and the associated mutual coupling scheme occurring in the reported array. The second section introduces a revised array topology that allows extending the scanning range up to the blind angle. The article focuses on the proof of concept of the proposed solution, which is based on the switching between two operating modes of the structure, each one covering a part of a globally wider scanning range. In the present case, the scanning capability of the array has been extended by 10° in the scanning plane of interest. Besides, the restored impedance matching allows for a 2 dBi gain improvement at the scan blindness angle.
Accurate time difference of arrival estimation for HF radio broadcast signals
Authors: Jain Ankit , Pagani Pascal , Fleury Rolland , Ney Michel M. , Pajusco Patrice 
Published: April 2018

AbstractGeolocation of high frequency (HF) transmitters at distances in the order of 2000 km is possible by exploiting the time difference of arrival (TDoA) among multiple distributed single antenna receivers. HF radio signals propagate via skywaves between the Earth‐Ionosphere medium and the signals are received through non‐line‐of‐sight mode. This experimental study demonstrates that it is possible to evaluate the TDoA between two receivers for a HF radio broadcast signal propagating through the ionospheric channel. The HF propagation path geometry for one hop propagation mode is explained. Simulations are performed using this model to evaluate the theoretical TDoA between the signals received at two synchronized receivers. In the second step, two remotely controllable receivers built to capture distinct HF signals are deployed in two cities in France. Radio broadcast signals from different HF transmitters across Europe are captured simultaneously on the two synchronized receivers. The TDoA is obtained by cross‐correlating the captured signals from the receivers. The TDoA obtained by experimental and simulation methods are compared for different radio propagation paths and results show some very good agreement.
Circularly polarized monopole hook antenna for ISM‐band systems
Authors: Donelli M. , Robol F. 
Published: April 2018

AbstractIn this letter, a circular polarized monopole hook antenna for ISM‐band applications is proposed. The antenna is printed on dielectric substrate and is fed by a 50 microstrip line. The antenna demonstrated good radiation properties, a wideband return loss, and a very good axial ratio. The influence of geometrical antenna parameters and in particular the hook angle which affect the antenna polarization are investigated and optimized. The obtained experimental results are in good agreement with the simulations.
Novel microstrip quadruplexer with wide stopband for WiMAX applications
Authors: Rezaei Abbas , Noori Leila 
Published: April 2018

AbstractThis work introduces a planar harmonic suppresser microstrip four‐channel multiplexer based on an originally novel geometrical structure. It consists of coupled lines connected to engraved semicircular cells. The realized quadruplexer operates at 3.211, 3.276, 3.38, and 3.491 GHz for IEEE 802.16 WiMAX. Wide stopbands above all passbands are obtained up to about 20 GHz so that fifth harmonics are attenuated properly. The semicircular structures provide quite close channels, which make it appropriate for FDD scheme. Compared to the previous reported quadruplexer, the common port return loss is decreased significantly, where improving the common port impedance matching for very close passbands is an important challenge. To minimize the circuit size, a new matching network consisting of coupled line and step impedance cell is embedded. To verify the designing methodology, the proposed multiplexer is fabricated and measured, where the simulated and measured results are in a good agreement.
Triple‐band hybrid antenna with integral isolation mechanism for MIMO applications
Authors: Das Gourab , Sharma Anand , Gangwar Ravi Kumar 
Published: April 2018

AbstractThis research article explains the designing of triband multiple input multiple output (MIMO) hybrid radiator for diversified wireless applications. It comprises of two symmetrically placed hybrid radiators. These hybrid radiators are placed on a FR4 substrate with protruded ground plane to provide maximum isolation
and improved diversity performance. Hybrid radiator consists of two C‐shaped printed lines and cylindrical dielectric resonator (CDR). A dual C‐shaped printed line behaves as a magnetic dipole and produces two different radiating modes in CDRA, that is, HE11δ and TE01δ mode. For confirming the simulated results, the prototype has been constructed and examined. Good agreement has been establish between simulated and experimental results. The proposed radiator is working over three frequency bands, that is, 1.86–2.60, 3.3–3.64, and 4.42–6.75 GHz. Different MIMO diversity performance parameters (ECC, DG, MEG, and CCL) are also examined and found to be in acceptable limit.
A compact open complementary split ring resonator inspired triband reconfigurable coplanar waveguide fed antenna
Authors: Rasool Maryam , Farooq Rabiya , Rashid Muhammad Hashir , Zafar Abdullah , Afzal Hira , Alimgeer Khurram Saleem , Ijaz Bilal , Iftikhar Adnan 
Published: April 2018

AbstractThis paper presents the implementation of open complimentary split ring resonator (OCSRR) structure in small rectangular radiating elements to achieve triple band and dual band reconfigurability using PIN diode. The proposed design is a coplanar waveguide fed structure and consists of three small radiating elements, whereas two OCSRR structures are coupled with the two‐radiating elements. The third radiating element embedded with OCSRR is connected using a PIN diode. Under DC biasing conditions the whole design resonates at three frequencies, that is,
,
, and
, whereas the proposed design switches to dual band operation at
and
in the diode ‘OFF’ state. The proposed structure is designed and fabricated on a single sided ungrounded FR
substrate. Overall, a good agreement between simulated and measured results is observed. It is also observed that the radiation patterns of the proposed antenna are the same with gains of
,
, and
at
, and
in the PIN diode ‘ON’ state, respectively, whereas in the diode ‘OFF’ state, at
the gain is
and at
the gain is
.
A reconfigurable miniaturized planar inverted‐F antenna with integrated BaSrTiO3 capacitor
Authors: Haskou Abdullah , Sharaiha Ala , Collardey Sylvain , Borderon Caroline , Ginestar Stéphane , Renoud Raphaël , Gundel Hartmut W. 
Published: April 2018

AbstractIn this letter, a wide‐tuning range planar inverted‐F antenna (PIFA) of 17 × 10 mm2 dimension printed on a Rogers duroid RT5880 substrate is presented. The printed circuit board (PCB) dimensions are 1 × 60 mm2. First, the antenna is simulated with a localized capacitor and the effect of the capacitor losses on the antenna efficiency is studied. Then, the antenna is simulated with an integrated BaSrTiO3 (BST) tunable capacitor. The obtained results are in very good agreement with those obtained with localized elements. Finally, the BST thin film capacitor is fabricated and mounted on the antenna. The experimental results show a capacitor tunability of 56.7% at a bias voltage of 35 V, leading to an antenna agility of 42.2%.
VHF suspended plate transmitter antenna design for DVB‐T and DAB‐T
Authors: Ali Abdul , Ciydem Mehmet , Altintas Ayhan , Koc Sencer 
Published: April 2018

AbstractThis paper presents the design of stacked suspended plate transmitter antenna for digital video and audio broadcasting. Contrary to conventional dipole structures, we have designed the antenna in VHF band (174–254 MHz) with two plates for wideband matching and design flexibility. Radiating primary plate has been excited by novel wideband modified inverted L‐type probe. Parasitic secondary plate, and vertical wall between primary plate, and ground plane have been used for further matching and beamwidth adjustment. A bandwidth of 42% and gain of 8.5 dBi is obtained at center frequency. Together with equivalent lumped element circuit model of designed antenna and experimental results for S11, gain, and radiation pattern are presented. To the best of authors knowledge this is the first stacked suspended plate antenna achieving a record bandwidth of 42% in VHF band.
Detection of different concentrated salt and sugar solution based on dielectric properties using microstrip technology
Authors: Rahman M. N. , Islam M. T. , Samsuzzaman M. 
Published: April 2018

AbstractThis article presents a microwave system to detect salt and sugar content in water using microstrip technology. The presented technology consists of a microstrip patch antenna which involves a tuning fork‐shaped patch and slotted partial ground plane. The antenna is printed on Rogers RT/duroid 5880 material with a thickness of 1.57 mm. The antenna has a compact physical size of 24 mm × 18 mm. Being used as a sensor the microstrip antenna detect the salt and sugar in water in terms of the reflection coefficient. The percentage of salt and sugar in water changes the dielectric properties which also change the reflection coefficients. In the practical experiments, the reflection coefficient decreases with the increment of the percentage of salt and sugar in water.
Design of a compact dual‐band monopole antenna using a top‐loaded octagon patch and perforated shorting pin
Authors: Park Jae Sung , Choi Hak Keun 
Published: April 2018

AbstractIn this article, an antenna operated in the dual band (824‐894 and 1750–2800 MHz) is proposed, and its performance is verified. The proposed antenna is structured with a monopole antenna of a reversed crossing trapezoidal type, over which a top‐loaded octagon patch is added; moreover, a perforated shorting pin is appended to the center of the reversed crossing trapezoidal monopole antenna. The performance is verified while changing the width at the connector between the top‐loaded octagon patch and reversed crossing trapezoidal monopole antenna and the width of the inverted‐L slit width after inserting it between the reversed crossing trapezoidal monopole antenna and the top‐loaded octagon patch. The monopole antenna of the crossed reversed crossing trapezoidal type has a broadband characteristic at the 1750‐ to 2800‐MHz band and can be run even in the 824‐ to 894‐MHz band by adding the top‐loaded octagon patch and perforated shorting pin. The antenna proposed in this study is a low‐profile antenna with a height of ∼λ/7 in the 824‐ to 894‐MHz (center frequency: 859 MHz) band, and it satisfies a return loss below −14 dB. The band characteristic at 1750–2800 MHz satisfies a return loss below −14 dB, even if the structure for the 824‐ to 894‐MHz band is added. The antenna gain is revealed as ∼−1 to 1 dBi in the 824‐ to 894‐MHz band.
Diffusion‐weighted magnetic resonance spectroscopy boosted by simultaneously acquired water reference signals
Authors: Döring André , Adalid Victor , Boesch Chris , Kreis Roland 
Published: April 2018

PurposeTo combine the metabolite‐cycling technique with diffusion‐weighted 1H‐MR spectroscopy and to use the inherent water reference for compensation of motion‐related signal loss for improved estimation of metabolite apparent diffusion coefficients (ADCs).MethodsDiffusion‐weighted spectra of water and metabolites were acquired simultaneously using metabolite‐cycling at 3 T. The water information was used for signal correction of phase, frequency, and eddy currents, as well as for compensation of motion‐induced signal loss. ADCs were estimated by 2D simultaneous fitting. The quality of ADC restoration was investigated in vitro. Subsequently, the new approach was applied in 13 subjects for enhanced metabolite ADC estimation in gray matter.ResultsMetabolite‐cycled diffusion 1H‐MRS is suitable to measure metabolite and water ADCs simultaneously. The water reference facilitates signal amplitude restoration, compensating for motion‐related artefacts. 2D fitting stabilizes the fitting procedure and allows the estimation of ADCs even for low signal‐to‐noise metabolites. Use of the motion‐compensation scheme leads to estimation of smaller ADCs for virtually all metabolites (44% smaller ADC on average), to a reduction of fitting uncertainties for metabolite ADCs in individual subjects and reduced variance over the cohort (45% smaller SD on average).ConclusionUsing the simultaneously acquired water signal as internal reference allows not only for compensation of phase and frequency fluctuations but also for signal amplitude restoration, and thus improved metabolite ADC estimation. Combination with 2D simultaneous fitting promises access to the diffusion properties even for low signal‐to‐noise metabolites. The combination of both techniques increases the specificity and sensitivity of estimated metabolite ADC values in the cohort.