A thin dual band circularly polarized (CP) patch antenna with a wide 3-dB axial ratio beamwidth (ARBW) is presented for BeiDou Navigation System (BDS) application. The CP radiation is achieved using simple stacked square patches for dual band radiation in the BDS B1 band (1561±2 MHz) and B3 band (1268±10 MHz). A `string moon' type branch extension technique is proposed to enhance the ARBW and axial ratio bandwidth in both operating bands. Loading 30° gap-type annular parasitic metal strips (APMS) further improves the ARBW in both operating bands. The experimental results show that the impedance bandwidth of the antenna is 6.3% (1.25-1.33 GHz) and 4.5% (1.52-1.59 GHz), and the axial ratio bandwidth is 1.6% (1.26-1.28 GHz) and 1.2% (1.55-1.57 GHz), respectively. In addition, the 3-dB ARBWs in the φ=0° and φ=90° planes are 185° and 184° at 1.268 GHz, respectively; and 222° and 211° at 1.561 GHz, respectively. The simulated results are in good agreement with the measured ones.
This paper presents the design, analysis, and developments of a reconfigurable hybrid metal-graphene filter for terahertz applications. In fact, through the graphene material, we can reconfigure both the resonance frequency and the bandwidth. Further, the variation in chemical potential, relaxation times, and temperature of graphene provides excellent proprieties performances, with a variation of the resonant frequency from 8.60 THz to 8.85 THz, good return loss reaching -22.94 dB and a bandwidth reconfiguration from 1.717 THz to 1.930 THz. The simulation of the proposed filter is performed using CST software.
In this paper, a bandwidth improvement technique in SIW slotted antennas is presented. Distinct from conventional SIW antennas with multiple cavity modes, a single cavity mode (TE210) is utilized to improve the bandwidth. When a rectangle slot is loaded at bottom surface of the cavity, the TE210 cavity mode is perturbed. As a result, two independent modes (odd TE210, even TE210) are introduced and merged in close proximity. Finally, the antenna is fabricated and tested. The measured results render an impedance bandwidth of 12.8% and a maximum gain of 7.1 dBi. The cross-polar level of maximum -29 dB and -34 dB is at 9.73 GHz and 10.63 GHz, respectively. The proposed design holds many features such as easy fabrication and light weight. Besides, the proposed design is a single-layered that makes it extremely convenient to integrate with other planar configurations.
This paper presents the analysis and design of in-phase/out-of-phase power dividers with compact-size and ultra-wideband characteristics. The proposed designs are composed of a T-junction microstrip (MS)-to-slotline power divider with a shorting via and two slotline-to-MS transitions. The phase response at the outputs can be controlled by arranging the MS-line direction of the transition, i.e., the same direction results in the in-phase, whereas the opposite MS-line directions reverse the electrical field, thus resulting in the out-of-phase. Thanks to utilizing the MS-to-slotline power divider and circular slots and circular stubs at the transitions, the proposed structures achieve ultra-wide bandwidth and compact size simultaneously. The dividers are theoretically analyzed using transmission-line equivalent circuit, and then verified computationally and experimentally. Simulation and measurement indicate that the proposed power dividers yield ultra-wideband performance across 1.2-11.0 GHz (~160%) with magnitude difference ±0.5 dB and phase difference ±5° at the outputs. As an example of application, a differential-fed Vivaldi antenna fed by the proposed out-of-phase power divider is implemented. The antenna yields a 160% bandwidth (1.2-11.0 GHz) for 10-dB return loss and a stable end-fire radiation within the whole impedance bandwidth.
In this paper, novel mode switchable microwave coupled line couplers on ferrite substrates are presented. The couplers are realized in Composite Right/Left Handedcoplanar waveguide configurations. Two different types of mode switchable couplers are proposed. The first one can switch the power from the backward coupling port to the through port. The second one can switch the power from the backward coupling port to both the through and forward coupling ports. In both cases, the mode switching is achieved by varying the applied DC magnetic bias. The theoretical analysis of the switching mechanism has been carried out based on the general coupled mode approach. The analysis is then verified numerically and experimentally. The measurement results confirm the switching functionalities of the fabricated couplers with better than 10 dB isolation between the switched signals. Moreover, these novel mode switchable couplers are compact and require very low external DC magnetic bias due to their CPW configurations. These new proposed switrches can be applied in the smart microwave compoennts in different radar/communication application.
A novel compact two-side anti-metal tag antenna for radio frequency identification (RFID) applications is proposed in this paper. The proposed tag antenna is composed by three aluminum patches separated by two layers of foam substrates. Particularly, the middle patch of the antenna is designed as three nested deformable rings for the miniaturization of antenna and realizes better power transmission coefficient (PTC) between the antenna and tag microchip. The antenna operates at the center frequency of 915 MHz and maintains a compact size of 35 mm × 22 mm × 2.15 mm (0.1068λ0 × 0.0671λ0 × 0.0066λ0). When the front or back side of the tag antenna is mounted on a large background metallic plate and tested with an effective-isotropic-radiated-power (EIRP) of 4 W, the antenna can achieve the maximum read distances of 6.23 m or 6.08 m. The tag antenna shows various advantages, including small size, low profile, and good antenna performance. Most importantly, the proposed tag antenna has two-side anti-metal property compared to a traditional single-side anti-metal antenna, which fulfills the emerging demands in the industrial internet of things field.
Magnetic gears (MGs) have many advantages over mechanical gears, including high efficiency, no contact, no lubrication, and low noise. Even though MGs are energy-efficient, cogging torque and torque ripple are always challenging, especially at low-speed applications. Generally, the cancellation of cogging torque enhances the performance of the operation of PM machines. This article proposes an approach based on slicing technique through which reduced cogging torque and improved torque density can be achieved in MGs. The two-dimensional finite element method (2D FEM) has been used to analyze the models using Simcenter and MATLAB software packages. The results show that the elimination of cogging torque of the proposed models compared to the base model is 97.53% on the inner rotor, and that of the outer rotor is 42.23%. Also, the torque density is slightly improved by 0.05% on the inner rotor while 0.1% improvement on the outer rotor is obtained.
This paper presents a low-cost antenna integrable to a large set of indoor common building materials. Employing the printing technology on thin transparent polyethylene terephthalate material and using available building materials not only leads to a low-cost environmentally friendly solution for the expected massive sensor deployment but also eliminates the dispersive behavior of the materials that are interacting with them. A coplanar-strips fed fractal folded antenna element was designed and validated experimentally with four different materials including gypsum, plywood, and plexiglass. The aesthetically viable ground-free antenna achieves wideband performance and radiates in the broadside plane perpendicularly to the wall. The single antenna element covers the frequency band of 2.18-3.96 GHz with a gain of 1 dBi at 2.4 GHz. To take advantage of the large available surface, a high efficiency 2.4 GHz array rectenna for powering electronic devices intended for IoE technology is proposed. The proposed array rectenna has a dimension of 384×354×6.475 mm3 and employs a single diode as the rectifier element. The measured results for the presented array rectenna reveal an AC-DC power-conversion-efficiency (PCE) of more than 20% for input powers as low as 0.025 μW/cm2 with a peak PCE of 61.3% at 4.03 μW/cm2.
In order to improve the reliability and continuous navigation of ship propulsion, a diesel-electric hybrid field modulation motor with bread-loaf eccentric magnetic poleis proposed in this paper. The permanent magnet of the inner rotor of the motor adopts a bread-loaf eccentric magnetic pole structure and is embedded and fixed on the iron yoke of the inner rotor. The structure can obtain a sinusoidal air gap magnetic field, to reduce the torque ripple of the motor. In this study, some key parameters of the motor are optimized by using the optimization strategy of the combination of genetic algorithm and finite element method. In addition, compared with the conventional magnetic field modulation motor with surface mounted permanent magnet, the motor has a stronger rotor structure. The back-EMF, torque and loss of the motor are calculated. The proposed motor has good sinusoidal back-EMF, less loss, and better stability. Finally, the working modes of the motor in the diesel-electric hybrid ship propulsion system are mainly diesel internal combustion engine driving mode, electric propulsion mode, and hybrid propulsion mode. The system can improve the reliability and continuous navigation of the ship propulsion system.
This paper presents an efficient Taguchi-preconditioned genetic algorithm (TPGA) strategy for the design optimization of a 630-kW permanent magnet vernier motor (PMVM). In the TPGA, firstly, the Taguchi method is combined with comparative finite element analyses (FEA) to judge the influence factors of six typical structural parameters on the torque output. Secondly, four influential parameters are taken from the six typical ones and decided as the variables in the global optimization processes coupling genetic algorithm (GA) and FEA. As two variables with small influence factors are set to constants in the computationally costly optimization processes, the calculation burden can thus be effectively reduced. Thirdly, with the four influential optimization variables, FEA-assisted GA is used to maximize the output torque of the PMVM. During the global optimization processes, a preliminarily optimized structural configuration obtained from the Taguchi analyses is used as the initial values of the variables. Finally, the working performances of the machine with the optimal parameters are obtained through FEM calculations. The optimization effectiveness is validated by comparing the output torque of the GA-optimized machine with that of the initial and the Taguchi-preliminary optimized ones.
In this paper, a compact triangular-shaped multiband Antenna is proposed for linear as well as circular polarization. The proposed Antenna is well-suitable for Wi-Max, C-band, and X-band applications. 2.4 GHz is very well suitable for RFID applications. The antenna is excited with a feed of variable width at one corner of the main patch. The parametric analysis has been done for feed width, slot cutting on the ground, and tapering cut at both remaining corners of the main patch. Circular polarization is achieved due to a tapering cut. It achieved circular polarization at 2.4 and 9.8 GHz and linear polarization at 4.31 and 6.75 GHz. The structure shows an impedance bandwidth of 2.13-3.02 GHz and 4.01-10.00 GHz. The measured peak gain is achieved to be 3.66 dB. A good agreement is found between simulated and experimental results.
A super wideband antenna is proposed to operate in the frequency band 2.2-22 GHz. The antenna has two planar arms printed on the opposite faces of a three-layer dielectric substrate. Each arm of the antenna is capacitively coupled to a circular ring near its end to increase the impedance matching bandwidth. The dielectric substrate is customized to fit the shape of the antenna arms and the parasitic elements to reduce the dielectric loss. The substrate material is composed of three layers. The upper and lower layers are Rogers RO3003TM of 0.13 mm thickness, and the middle layer is made of paper of 2.3 dielectric constant and 2.7 mm thickness. The antenna is fed through a wide band impedance matching balun of a novel simple design. A prototype of the proposed antenna is fabricated to validate the simulation results. The experimental measurements are in good agreement with the simulation results, and both of them show that the antenna operates efficiently over the frequency band 2.2-22 GHz with minimum radiation efficiency of 97% and maximum gain of 5.2 dBi. The antenna has a bandwidth to dimension ratio (BDR) of 1755.
A planar UHF RFID tag antenna with a hybrid nested slot and T-match network is presented. A novel T-match network in a nested slot is introduced to have superior conjugate impedance matching between tag antenna and the semiconductor microchip. Size curtailment is acquired by means of exploiting the T-match network branches and the feeder strip line. Moreover, expanding the nested slot area and increasing the T-match branch length modify the electrical length and increase the antenna inductance. Thus by utilizing the arm of matching network and feeder, conjugate impedance is achieved in accordance with the semiconductor chip at 865 MHz. A surpassing UHF tag with volume 120×60×1.6 mm3 (0.346λ×0.173λ×0.0046λ), with outstanding 10-dB return loss of 12 MHz has been flourishingly demonstrated, and it is able to obtain a detection range of 13.9 m. This tag antenna composition is simulated with respect to 4 W EIRP reader.
A novel ultrawideband (UWB) antenna with a single parasitic U-type element is reported to exhibit dual-band notch peculiarities. A slotted radiator and a novel defected ground structure (DGS) comprise the proposed antenna, which has a bandwidth of 2.9-11.75 GHz (121%) in the UWB spectrum. By etching a single inverted U-shaped parasitic element on top of the DGS, two rejected bands at the downlink of X-band (6.8-8 GHz) and the uplink of X-band (9.7-11.3 GHz) applications are achieved. The proposed antenna is printed on an FR-4 substrate with a compact size of 24×28 mm2, has a gain fluctuation of 1.4-5.7 dBi, and a peak radiation efficiency of 92.3%. The suggested antenna is a viable candidate for downlink and uplink X-band notched UWB applications owing to the excellent agreement between its measured and simulated results.
This paper aims to model and analyze planar antennas for high frequencies using an iterative wave design procedure (WCIP). The formulation adopted in the method allowed determining a basic equation for the interaction of linearly combined electromagnetic fields with the incident and reflected waves in various dielectric media over a discontinuity. In this paper, we design a broadband terahertz patch antenna using graphene. We propose to design a new numerical tool to model the implementation of graphene to achieve an efficient and flexible antenna. The design methodology started with the design of a compact conventional microstrip antenna for 118.87 GHz, and the antenna was then miniaturized using rectangular slots. Based on the simulation results, the suggested structure antenna with a slot can offer great characteristics in terms of broadband performance and frequency reconfiguration using various voltages on the graphene. The antenna provides frequency bands fr1 = 118.7 GHz, fr2 = 120 GHz, fr3 = 123.36 GHz, fr4 = 128.27 GHz, fr5 = 131 GHz and fr6 = 132.8 GHz with a bandwidth is Δfr1 = 9.5 GHz, Δfr2 = 3.66 GHz, Δfr3 = 4 GHz, Δfr4 = 3.23 GHz, Δfr5 = 3.401 GHz, Δfr6 = 3.01 GHz and uniform radiation patterns, the value of VSWR between 1 and 2 for different chemical potential value respectively μc = 0.1 eV, μc = 0.2 eV, μc = 0.3 eV, μc = 0.4 eV, μc = 0.5 eV, μc = 0.6 eV using polyimide with a dielectric constant of 3.5 and a loss tangent of 0.008. In addition, we studied the effect of different substrate materials (Arlon and Duroid 5880). The simulation is performed using a new WCIP equation, and the validation is performed by comparison with the finite integration method in technique (FIT). A comparison of the computation time is presented in this paper.
A dual-band flexible monopole antenna for wearable applications is presented. The antenna structure is built based on Tree-shaped fractal geometry. The suggested antenna is printed on Rogers RT5870, a semi-flexible material with a relative dielectric constant and loss tangent of 2.33 and 0.0012, respectively. According to the results, the proposed antenna achieves dual impedance bandwidth ranging from 1.72 GHz to 1.88 GHz for the lower band and 5.1 GHz to 5.33 GHz for the upper band. The simulated results show that the fractional impedance bandwidths and realized gains of the antenna are 8.9/4.8%, and 1.47/5.67 dBi for the 1.81/5.2 GHz, respectively. The antenna's performance under various bending scenarios has also been demonstrated at both resonant frequencies. The overall size of the proposed antenna is about 45×41×0.25 mm3. The antenna shows good performance to be a candidate for wearable applications.
In this paper, an innovative machine learning (ML) approach for the prediction of the output power generated by photovoltaic (PV) plants is presented. Toward this end, a two-step learning-by-examples (LBE) strategy based on support vector regression (SVR) is proposed to learn the complex relation among the heterogeneous parameters affecting the energy production of the power plant. More specifically, the first step is aimed at down-scaling the weather forecasts from the standard air temperature and the solar irradiance to the local module temperature and the plane-of-array (POA) irradiance. Then, the second step predicts the output power profile given the down-scaled forecasts estimated at the previous step. The advantages and the limitations of the proposed two-step approach have been experimentally analyzed exploiting a set of measurements acquired in a real PV plant. The obtained results are presented and discussed to point out the capabilities of the proposed LBE method to provide robust and reliable power predictions starting from simple weather forecasts.
A design of a modified bow-tie slot loaded wideband antenna using a Substrate Integrated Waveguide (SIW) cavity is proposed in this paper. The simple bow-tie slot perturbs the current distribution of the TE120 mode, which generates two hybrid modes, namely odd TE120 and even TE120 modes at 9.6 GHz and 10.8 GHz respectively, but the achieved bandwidth is only 500 MHz (5.2%). To increase the bandwidth, a short rectangular slot is incorporated at the middle of the bow-tie slot, which moves the hybrid odd TE120 mode to 10.2 GHz, near even TE120, which helps to achieve a wide bandwidth of 1.1 GHz ranging 9.9 GHz-11 GHz (10.5%), and also it exhibits a unidirectional radiation pattern. The proposed antenna is fabricated for experimental validation of the modified bow-tie slot antenna. The measured value of bandwidth is 1.1 GHz from 10.1 GHz to 11.2 GHz (10.3%) with a consistent gain of 6.25 dBi, and the variation between co-pol and cross-pol is maximal. Because of the wide bandwidth, high gain and compactness, the suggested antenna is suitable for satellite, radar, and all practical wireless applications of X-band frequencies.
A high performance substrate integrated waveguide (SIW) slotted array antenna with low sidelobe level and optimum gain at 28 GHz is designed, and experimental results are presented with simulated data. In order to achieve a low sidelobe level, Chebyshev power coefficients in the form of slot displacements are applied to the SIW array antenna. A MATLAB program has been written to find these slot displacements. This work entails investigating and designing the optimum microstrip to SIW transition over the Ka-Band, designing a 1 x 8 slotted SIW array antenna, and finally applying the Chebyshev power coefficients to the slots of the 1 x 8 SIW array antenna. The fabricated prototype of a 1 x 8 SIW slotted array antenna is tested, and its performance is studied in terms of gain and half power beam width (HPBW), compared with simulations. The measured results of the 1 x 8 slotted SIW array antenna at 28 GHz have a |S11| of better than -20 dB, a gain of 13 dB, and an HPBW of 17˚. The overall dimensions of the design at 28 GHz are 7.143 mm x 51.8 mm x 0.254 mm (0.667λo × 4.84λo × 0.023λo = 0.0766λo3 mm3).
This article proposes a compact dual-band circle-shaped implantable antenna for scalp and skin implantation applications. The proposed antenna covers the 1.395-1.432 GHz Wireless Medical Telemetry Service (WMTS) band and 2.4-2.48 GHz Industrial, Scientific, and Medical (ISM) band with a compact volume of 0.0000017λ03. The antenna maintains a realized peak gain of -24.5 dB and -20.6 dB, respectively, at 1.43 GHz and 2.44 GHz. Moreover, the gain pattern of the antenna is in the off-body direction which is a desirable feature for implantable scenario. It also depicts stable responses under different implantation scenarios. Moreover, the via free configuration is an advantageous feature of the proposed antenna in the context of fabrication complexity. Furthermore, a holistic design approach is considered with integrated components for device-level architecture. The resonance behavior of the proposed antenna structure is also analyzed by developing a conceptual equivalent circuit model. The evaluated specific absorption rate (SAR) complies with the regulated human safety standard. The biotelemetry link capability is also evaluated through the link margin (LM) calculation of the proposed antenna and is able to establish a communication link at a range of 4.5 m distance.