scholarly journals Estimating Electric Field and SAR in Tissue in the Proximity of RF Coils

2020 ◽  
pp. 293-307
Author(s):  
Rosti Lemdiasov ◽  
Arun Venkatasubramanian ◽  
Ranga Jegadeesan
Keyword(s):  
Electric Field ◽  
Computational Time ◽  
Rf Coils ◽  
Induced Current ◽  
Resonant Coupling ◽  
Simulation Tools ◽  
Full Wave ◽  
Rf Exposure ◽  
Simulation Based ◽  
Full Wave Analysis

AbstractMedical implants that require recharging typically use magnetic resonant coupling of transmit (external) and receive (internal) RF coils. Apart from magnetic field, the transmit coil creates a time-varying electric field that excites currents not only in the receive coil but also in the surrounding tissues. Radio frequency (RF) exposure assessment for inductive systems used in wireless powering and telemetry is done using electric field, specific absorption rate (SAR), and induced current as metrics. Full-wave analysis using RF simulation tools such as Ansys HFSS is generally used to estimate these metrics, and the results are widely accepted. However, such simulation-based analysis is quite rigorous and time-consuming, let alone the complexities with setting up the simulation.In this paper, we present a simple approach to estimating exposure (electric field, SAR, induced current) from fundamental electromagnetic principles enabling ability to arrive at results quickly. It significantly reduces the computational time in iterative approaches where multiple simulation runs are needed.

scholarly journals On geometry parameterization for simulation-driven design closure of antenna structures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Slawomir Koziel ◽  
Anna Pietrenko-Dabrowska
Keyword(s):  
Computational Cost ◽  
Major Effect ◽  
Dimensional Parameter ◽  
Simulation Tools ◽  
Full Wave ◽  
Simulation Based Design ◽  
Simulation Based ◽  
Monopole Antennas ◽  
Geometry Parameterization ◽  
Design Closure

AbstractFull-wave electromagnetic (EM) simulation tools have become ubiquitous in antenna design, especially final tuning of geometry parameters. From the reliability standpoint, the recommended realization of EM-driven design is through rigorous numerical optimization. It is a challenging endeavor with the major issues related to the high computational cost of the process, but also the necessity of handling several objectives and constraints over often highly-dimensional parameter spaces. From the numerical perspective, making decisions about the formulation of the optimization problem, the approach to handling the design constraints, but also parameterization of the antenna geometry, are all non-trivial. At the same time, these issues are interleaved, and may play an important role in the performance and reliability of the simulation-based design closure process. This paper demonstrates that the approach to arranging the structure parameterization (e.g., the use of absolute or relative parameters) may have a major effect of the optimization outcome. Our investigations are carried out using three broadband monopole antennas optimized under different scenarios and using different parameterizations. In particular, the results indicate that relative parameterization is preferred for optimization of input characteristics, whereas absolute parameterization is more suitable for size reduction.

scholarly journals Optimal Design of Aperiodic Reconfigurable Antenna Array Suitable for Broadcasting Applications

Electronics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 818 ◽  
Author(s):  
Ioannis P. Gravas ◽  
Zaharias D. Zaharis ◽  
Pavlos I. Lazaridis ◽  
Traianos V. Yioultsis ◽  
Nikolaos V. Kantartzis ◽  
...  
Keyword(s):  
Antenna Array ◽  
Optimization Methods ◽  
Base Station ◽  
Service Area ◽  
Center Frequency ◽  
Computational Time ◽  
Full Wave ◽  
Low Sidelobe ◽  
Full Wave Analysis ◽  
Velocity Mutation

An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station antenna operating in a single broadcasting channel. The antenna array is optimized at 698 MHz (center frequency of DVB-T channel 49) to concurrently achieve a particular radiation pattern shaping with high forward gain, main lobe tilting and null filling inside the service area, as well as low sidelobe level outside the service area, and low standing wave ratio at the inputs of all the array elements. To concurrently satisfy all the above requirements, both the geometry dimensions and the array feeding weights (amplitudes and phases) are optimized, thus leading to a complex multi-variable and multi-objective problem. The problem is solved by applying a recently developed particle swarm optimization (PSO) improved variant, called PSO with velocity mutation, in conjunction with the CST software package, which is employed by the PSOvm every time a full-wave analysis is required. Furthermore, all the optimization methods found in the CST environment are compared with the PSOvm. The results show that the PSOvm is capable of producing an antenna array geometry, which is closer to the predefined requirements than the geometries derived by the rest of the optimizers, in the least amount of computational time.

On geometry parameterization for simulation-driven design closure of antenna structures

2021 ◽  
Author(s):  
Slawomir Koziel ◽  
Anna Pietrenko-Dabrowska
Keyword(s):  
Computational Cost ◽  
Major Effect ◽  
Dimensional Parameter ◽  
Simulation Tools ◽  
Full Wave ◽  
Simulation Based Design ◽  
Simulation Based ◽  
Monopole Antennas ◽  
Geometry Parameterization ◽  
Design Closure

Abstract Full-wave electromagnetic (EM) simulation tools have become ubiquitous in antenna design, especially final tuning of geometry parameters. From the reliability standpoint, the recommended realization of EM-driven design is through rigorous numerical optimization. It is a challenging endeavor with the major issues related to the high computational cost of the process, but also the necessity of handling several objectives and constraints over often highly-dimensional parameter spaces. From the numerical perspective, making decisions about the formulation of the optimization problem, the approach to handling the design constraints, but also parameterization of the antenna geometry, are all non-trivial. At the same time, these issues are interleaved, and may play an important role in the performance and reliability of the simulation-based design closure process. This paper demonstrates that the approach to arranging the structure parameterization (e.g., the use of absolute or relative parameters) may have a major effect of the optimization outcome. Our investigations are carried out using three broadband monopole antennas optimized under different scenarios and using different parameterizations. In particular, the results indicate that relative parameterization is preferred for optimization of input characteristics, whereas absolute parameterization is more suitable for size reduction.

Full-wave analysis of shielded coplanar waveguide short-end

1990 ◽  
Vol 26 (19) ◽  
pp. 1615 ◽  
Author(s):  
G. Bartolucci ◽  
J. Piotrowski
Keyword(s):  
Coplanar Waveguide ◽  
Wave Analysis ◽  
Full Wave ◽  
Full Wave Analysis

Erratum: Full-wave analysis of shielded coplanar waveguide short-end

1990 ◽  
Vol 26 (22) ◽  
pp. 1922
Author(s):  
G. Bartolocci ◽  
J. Piotrowski
Keyword(s):  
Coplanar Waveguide ◽  
Wave Analysis ◽  
Full Wave ◽  
Full Wave Analysis

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

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