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Vol. 99, 179-195, 2023
download: 191
Acceleration of the Primary Basic Functions Calculation from the EFIE-Characteristic Basis Function Method (CBFM) Combined with a New Physical Optics Approximation
Christophe Bourlier
This paper presents a new scheme to implement the iterative physical optics (IPO) approximation with edge diffraction for the scattering from large perfectly-conducting objects, for which, multiple reflections occur. The use of the electric field integral equation (EFIE) discretized by the Galerkin method of moments (MoM) with Rao-Wilton-Glisson basis functions leads to solving a linear system. The characteristic basis function method (CBFM) needs to invert the self-impedance sub-matrices to calculate the primary basis functions (PBFs). To accelerate this stage, these sub-linear systems are directly solved from the physical optics (PO) approximation. In addition, to improve the precision of PO, the EFIE-PO self-impedance matrix is derived analytically. This avoids to apply the magnetic field integral equation (MFIE), for which its principal value is related to PO. Numerical results showed that the resulting algorithm, CBFM-PO, predicts inherently the edge diffraction. A domain decomposition method is able to split up the geometry into blocks, for which either the PO or a LU decomposition is applied according to the sub-geometry. To accelerate the coupling steps, the adaptive cross approximation (ACA) is also implemented, and the resulting method is tested on different targets having a curvature and producing multiple reflections. The numerical results show that EFIE-CBFM-PO is more accurate than the conventional EFIE-CBFM-POJ (based on Jakobus et al. work), specially for objects with curvature.
Acceleration of the Primary Basic Functions Calculation from the EFIE-characteristic Basis Function Method (CBFM) Combined with a New Physical Optics Approximation
Vol. 99, 159-178, 2023
download: 179
A Canonical Filter Theory Approach for the Synthesis of Inductive Wireless Power Systems with Multiple Resonators
Masoud Ahmadi , Tristan Vander Meulen , Loïc Markley and Thomas Johnson
The advantage of the canonical filter theory approach to design inductive power transfer (IPT) systems is that values for the coupled resonator elements are readily calculated from scaled canonical filter prototypes with specific frequency response characteristics. For example, Butterworth bandpass filter prototypes can be used to synthesize resonant-coupled IPT systems with critically-coupled frequency response characteristics. In this work, we analyze two canonical filter prototype structures: one prototype has series matching elements at the ports, and the other prototype has shunt matching elements at the ports. Equations are provided to transform the networks into coupled resonator structures that implement IPT links with a transmitter, receiver, and multiple repeater coils. The filter methodology for IPT link synthesis also provides an easy framework to evaluate design trade-offs. An example of comparing resonator inductor sizes for both the series and shunt matching topologies is shown for IPT links operating in ISM frequency bands of 6.78 MHz, 13.56 MHz, 27.12 MHz, and 40.68 MHz. Experimental results are shown for four different IPT examples that were designed using filter synthesis methods.
A Canonical Filter Theory Approach for the Synthesis of Inductive Wireless Power Systems with Multiple Resonators
Vol. 99, 139-157, 2023
download: 176
Dual-Band Hexagonal SRR Antennas and Their Applications in SIMO and MISO-Based WLAN/WiMAX Systems
Puneet Sehgal and Kamlesh Patel
This article presents the performance of a hexagonal split-ring resonator (H-SRR) antenna in the 2.4/5.2 GHz bands and evaluation of channel capacity for single-input multiple-output (SIMO) and multiple-input single-output (MISO) systems. The proposed antenna consists of two hexagonal-shaped split-ring resonators for dual-band operation with higher gain and metallic loadings between the rings to achieve a wide impedance bandwidth. Impedance modeling of the proposed antennas confirms the role of conductance and inductance of metallic loading for enhancing the antenna characteristics, and thus, the fabricated H-SRR antenna achieves dual-band features with improved impedance bandwidth of 50%/76% and a gain of 2.32/2.57 dB at 2.4/5.2 GHz frequency bands. The performance of the hexagonal SRR antenna is then investigated for space diversity applications in the 1×3 SIMO and 3×1 MISO systems with circular SRR antennas. In linear and spherical arrangements of the antennas, the channel capacity is found in the range of 2.7 to 4.8 Mbps at the 2.4/5.2 GHz bands, which also confirms its dependency on the number of antennas as well as on the placement of antennas.
Dual-Band Hexagonal SRR Antennas and Their Applications in SIMO and MISO-based WLAN/WIMAX Systems
Vol. 99, 121-138, 2023
download: 154
Terahertz Sub-Wavelength Focusing and Negative Refraction Assisted Beam Transferring Based on 3-d Metamaterial Flat Lens Configurations
Marishwari Muthusamy , Venkatachalam Subramanian , Zhengbiao Ouyang and Natesan Yogesh
A flat lens made of a negative index (NI) metamaterial (MTM) focuses the diverging light waves with sub-wavelength resolution. However, to achieve tight 3-D focusing, one needs to realize a 3-D MTM with azimuthal and elevation focusing. In this work, a polarization-insensitive, wide-incident angle 3-D MTM showing an NI band of 0.34 THz (37%) centered at 0.92 THz is realized. A flat lens designed out of the proposed 3-D NI MTM shows sub-wavelength spot sizes of 0.48λ1 and 0.39λ2 for cylindrical electromagnetic (EM) waves emanating out of an electric dipole source, at 0.9 THz and 0.95 THz respectively. Also, the sub-wavelength focusing features of the NI flat slab are verified along non-symmetric planes by tilting the dipole source for different angles. It is also found that the finite flat slab configurations efficiently transfer EM beams for long conveyance lengths at NI frequencies. Thus, the realized flat slab configurations are useful for 3-D focusing requirements in optical trapping and imaging, and they are also useful for reducing the transmission losses associated with beam divergences.
Terahertz Sub-wavelength Focusing and Negative Refraction Assisted Beam Transferring Based on 3-D Metamaterial Flat Lens Configurations
Vol. 99, 103-119, 2023
download: 169
A Novel Circularly Polarized Annular Slotted Multiband Rectenna for Low Power Sensor Applications
Neeru Kashyap , Geetanjali and Dhawan Singh
To overcome electronic device dependence on energy storage medium, current research proposes a novel multiband circularly polarized (CP), microstrip patch antenna with a voltage multiplier rectifier circuit for wireless energy harvesting. The proposed antenna is designed with a dimension of 50 mm × 50 mm × 0.16 mm (0.80λ × 0.80λ × 0.028λ). Its annular slot and slits on a circular patch along with a defective ground plane result in a miniaturized, circularly polarized, and multiband response with resonance peaks at 6.3 GHz, 7.4 GHz, and 9.1 GHz, respectively. The voltage multiplier rectifier circuit is designed, optimized, and integrated with the antenna for RF signals to DC power conversion in order to energize low-power sensors-based application modules. The simulated multiband antenna resonates at three frequencies of 6.3 GHz, 7.4 GHz and 9.1 GHz with obtained -10 dB impedance bandwidths of 282 MHz (6.276 GHz-6.549 GHz), 178 MHz (7.348 GHz-7.526 GHz), and 81 MHz (9.136 GHz-9.217 GHz), gain of 6.3 dBi, 10.28 dBi, and 7.9 dBi and axial ratio bandwidth of (6.297 GHz-6.302 GHz), (7.783 GHz-7.411 GHz) and (9.256 GHz-9.473 GHz), respectively. The prototype is fabricated, and its resonance peaks are observed at 6.2 GHz, 7.8 GHz and 9.3 GHz with impedance bandwidth of 195 MHz, 206 MHz and 230 MHz and gain of 6.3 dBi, 9.6 dBi, and 7.4 dBi, respectively. The rectifier circuit is analyzed over the power range -20 dBm to 20 dBm and exhibits an increase in the DC output power significantly with a maximum measured efficiency of 53.34% at a frequency of 7.4 GHz with an associated load resistance of 1 kΩ.
A Novel Circularly Polarized Annular Slotted Multiband Rectenna for Low Power Sensor Applications
Vol. 99, 83-102, 2023
download: 187
Improving the Efficiency of Solar Systems by Tracking the MPP Under Different Test Conditions
Alaa Shakir Mahmood and Mustafa Teke
The great technological development, the increase in the number of factories, and the large population growth led to an increase in the demand for the consumption of electric energy that we get from traditional methods (fossil fuels). Moreover, the global shortage in fossil fuel sources and their high costs, the global financial and economic crisis, and the harmful emissions it causes for the environment have made researchers look for electrical energy from alternative and environmentally friendly sources. As a renewable energy, solar energy is considered one of the most important sources of electrical energy today because it is easy to obtain at a low cost. However, this type of energy suffers from low efficiency and is greatly affected by changing weather conditions. To address this problem, several techniques have been proposed by research groups, and MPPT is one of those techniques that has been frequently used in recent years to extract maximum power from solar panels despite the instability in weather conditions. This technique can also generate pulses to control the DC-DC boost converter to provide a certain level of voltage. In this paper, three algorithms, namely Perturbation and Observation (P&O), Fuzzy Logic Controller (FLC), and Particle Swarm Optimization (PSO) are modified and applied in the MPPT technology to control the duty cycle of a DC-DC converter. The photovoltaic system consisting of MPPT technology, solar panels, and a DC-DC boost converter was simulated using MATLAB/Simulink. The performances of the three algorithms were compared to determine the best one that guarantees the highest efficiency under multiple test conditions. The simulation results show that PSO was a better performer than others with (99.32%, 97.02%, and 98.33%, respectively).
Improving the Efficiency of Solar Systems by Tracking the MPP under Different Test Conditions
Vol. 99, 63-81, 2023
download: 173
An Analytical Approach for Pulse Compression Favorable Digitized Frequency Modulated Thermal Wave Imaging Technique for the Quantitative Estimation of Breast Cancer
Anshul Sharma , Vanita Arora and Ravibabu Mulaveesala
Among several noninvasive diagnostic modalities used for identifying and assessing breast cancer, a recently proposed digitized frequency-modulated thermal wave imaging (DFMTWI) has emerged as a widely applied active thermographic technique. DFMTWI has demonstrated its capabilities for early diagnosis and quantitative evaluation of breast cancer by exhibiting better pulse compression properties. This approach delivers better depth resolution and sensitivity than standard thermographic techniques. The current research illustrates the novel analytical model for the pulse compression favorable DFMTWI technique for the quantitative estimation of breast cancer. Using Green's function approach, an analytical model has been solved by considering the multilayer Pennes bioheat transfer equation with adiabatic boundary conditions and a constant initial condition. The conventional thermographic techniques (such as Lock-in Thermography (LT) and Pulse Thermography (PT)) are also solved with a similar approach as followed for DFMTWI. The results obtained for the proposed DFMTWI and the conventional LT and PT thermographic techniques are then compared and validated with the numerical results obtained from the numerical simulation considering the correlation coefficient as a figure of merit for early-stage breast cancer diagnosis.
An Analytical Approach for Pulse Compression Favorable Digitized Frequency Modulated Thermal Wave Imaging Technique for the Quantitative Estimation of Breast Cancer
Vol. 99, 41-62, 2023
download: 177
Design of Waveguide Applicators Using a Quarter-Wave Transformer Prototype
Mykola Zhuk and Jonathan Paradis
In this paper, we propose a design methodology for waveguide applicators to maximize microwave power deposition into human tissues. The optimized applicators can be used in the experimental studies of the biological effects of exposure to electromagnetic radiation in the frequency range from 6 GHz to 100 GHz. The design methodology relies on the provision of reflectionless matching of a dissipative waveguide load, achieved by employing a matching network based on a quarter-wave transformer prototype. The prototype is synthesized by knowledge of the voltage standing wave ratio (VSWR) evaluated in the unmatched loaded waveguide. A key difference from the conventional synthesis procedure is that in our design approach, the characteristic impedance of the first transformer section is given, and we have to not only determine the characteristic impedances of the remaining sections, but also establish the output load. A solution of this synthesis problem and the process of converting the transformer prototype into a waveguide structure are described. The physical structure can be implemented according to provided sample models of waveguide WR137 applicators employing symmetric inductive or capacitive posts. The matched waveguide applicators are easy to manufacture, and according to the results from computational simulations, they demonstrate superior performance compared to the unmatched waveguides. Limitations of our designs (narrow bandwidth, dependence on the type of tissues encountered, limited potential for miniaturization) are discussed.
Design of Waveguide Applicators Using a Quarter-wave Transformer Prototype
Vol. 99, 23-39, 2023
download: 216
Self-Inductance Computation of the Thin Conical Sheet Inductor
Slobodan Babic
In this paper, a new formula for calculating the self-inductance of a thin conical sheet inductor is given. The presented work is derived in a semi-analytical form based on the complete elliptic integrals of the first, second, and third kind plus a term to be solved numerically. The analytical formula is obtained in the special case when the thin conical sheet inductor is degenerated into a thin wall cylinder. The validation of the presented formulas is done by triple, double, single integration and by the semi-analytical formula. These self-inductance calculations of the thin conical sheet inductors can be especially useful in broadband RF applications and wireless power transfer systems where conical inductors have been used.
Vol. 99, 1-21, 2023
download: 163
Simulation of Rapid Voltage Edge Related Voltage Surges in Highly Inductive Windings with Frequency Dependent Parameters
Roberto Felicetti , Jesus Jose Perez-Loya and Claes Urban Lundin
Many static and rotating electric energy converters make use of inductive coils as filters, reactive loads or exciters, where a sudden variation of the magnetizing current can produce severe overvoltage with potential subsequent insulation damage. In some applications the overvoltage is the result of a superposition of travelling voltage waves in a supplying line. Traditional tools for studying such phenomena are based on ordinary differential equations that can heavily handle variable parameters, especially if they change according to the rapidity of the observed overvoltage. In this paper the transient voltage distribution in the excitation winding of a salient pole synchronous generator is simulated by solving the problem entirely in the frequency domain, i.e., without any use of the traditional ordinary differential equations solvers. Thismakesit possible to tune the parameters of a simplified electric model to the frequency response of the studied winding. It is shown that for highly inductive windings a single transmission line model with frequency dependent parameters can reproduce voltage transients very accurately, in a broad interval of frequency, relevant for power electronics and electromagnetic compatibility applications. Furthermore, the paper presents the experimental setup which has been needed for generating the fast varying voltage edges.
Simulation of Rapid Voltage Edge Related Voltage Surges in Highly Inductive Windings with Frequency Dependent Parameters