Jin-Kyu Byun

Design of Dielectric Waveguide Filters Using Topology Optimization Technique

A topology optimization technique is applied to the design of dielectric-loaded waveguide filters. Dielectric material distribution inside the waveguide is optimized to achieve desired frequency response. A gradient-based optimizer is used for topology optimization, along with adjoint variable method to calculate sensitivity. The results of numerical examples show feasibility of the proposed method

Robust design of dual band/polarization patch antenna using sensitivity analysis and Taguchi's method

In this paper, sensitivity analysis and Taguchis method are applied to the design of dual band patch antenna using gap coupling. The proposed structure uses T-slotted aperture coupling between patch and feed line of ground plane. Using sensitivity analysis, optimum dimensions of patch and coplanar waveguide (CPW) feed line are first sought. Then the optimized values are modified by Taguchis method in order to obtain robustness against the change of material constant and gap between patch and feed line. Moreover, the validity of the robust design has been tested with two antennas manufactured according to the final design. From the numerical and experimental results, it is confirmed that the final design is insensitive to noise factors.

A New Unified Design Environment for Optimization of Electric Machines Based on Continuum Sensitivity and B-Spline Parametrization

In this paper, a unified design environment is developed for the optimization of electric machines based on continuum sensitivity. For electromagnetic (EM) system analysis, COMSOL scripting environment is used. Optimization module is developed by MATLAB programming, which can be combined with COMSOL script commands. The modules are combined into one MATLAB project, and iteration process necessary for the optimization of EM system can be performed efficiently. During the design process, visual feedback of the current design status is given to the designer. In addition, the B-Spline parametrization of the nodal points is implemented to obtain smooth boundary of the device. The developed software is applied to the problem of finding uniform flux density distribution at the air gap of an electromagnet to verify its feasibility and effectiveness.

Induced Current Calculation in Detailed 3-D Adult and Child Model for the Wireless Power Transfer Frequency Range

Induced current density in the human body is the basic restriction of the electromagnetic field protection guidelines for frequencies . Due to the difficulty of measurement, numerical methods are often used for assessment of basic restrictions. In this paper, induced current distributions are calculated in the high-resolution 3-D adult and child models exposed to magnetic fields between 100 kHz and 10 MHz, which is the frequency range of the resonant wireless power transfer (WPT) systems. For this frequency range, it is difficult to apply the conventional finite-difference time-domain (FDTD) method for bioelectric field computation. Thus, the quasi-static FDTD method is used to reduce the number of time steps. The results are analyzed according to different human models, grounding conditions, organs, frequencies, and orientations of the incident magnetic field. In addition, the plane wave exposure is compared with exposure to magnetic field of transmit coil of WPT system. Using the calculation results, the feasibility of the magnetic field reference level in the International Commission on Non-Ionizing Radiation Protection guideline is analyzed.

Faster calculation of sensitivity in the source current distribution problem using reciprocity theorem

A new and faster sensitivity calculation algorithm for the source current distribution problem is proposed, The reciprocity theorem is used to reduce the calculation time. The proposed method is efficient when there are a large number of design variables.

A New Material Sensitivity Analysis for Electromagnetic Inverse Problems

This paper presents a new self-adjoint material sensitivity formulation for optimal designs and inverse problems in the high frequency domain. The proposed method is based on the continuum approach using the augmented Lagrangian method. Using the self-adjoint formulation, there is no need to solve the adjoint system additionally when the goal function is a function of the S-parameter. In addition, the algorithm is more general than most previous approaches because it is independent of specific analysis methods or gridding techniques, thereby enabling the use of commercial EM simulators and various custom solvers. For verification, the method was applied to the several numerical examples of dielectric material reconstruction problems in the high frequency domain, and the results were compared with those calculated using the conventional method.

Application of the Sensitivity Analysis to the Optimal Design of the Microstrip Low-Pass Filter With Defected Ground Structure

This paper shows applied sensitivity analysis for easier design and practical application of a planar half-wavelength low-pass filter (LPF) using defected ground structure (DGS). Typically, it is difficult to deploy planar half-wavelength low-pass filters when high power durability is required because of the very narrow line-widths of high impedance transmission line. Here, we propose a new configuration for the high impedance microstrip line using DGS structure to allow broader line width and high power handling capability. The sensitivity of the scattering parameters was calculated using the self-adjoint sensitivity formula in order to determine the proposed filters dimension. The paper also highlights the validity of the proposed LPF optimization with its measured performance.

Optimal Design of a RFID Tag Antenna Based on Plane-Wave Incidence

In order to increase the detection range and radar cross section (RCS), the patch shape of a UHF RFID tag antenna is optimized using continuum design sensitivity analysis. To maximize RCS and reflect the practical RFID tag operating condition, the design goal is set considering not only the matching characteristics of the antenna but also the induced voltage at the RFID chip terminal when the plane-wave is incident upon the antenna. The complex impedance of the RFID chip is taken into account by defining a lumped port at the chip location. The design results show that the induced voltage at the chip has increased more than 32% after the optimization.

Design Optimization of Waveguide Filters Using Continuum Design Sensitivity Analysis

This paper presents a new methodology for design optimization of dielectric waveguide filters based on the continuum design sensitivity analysis in conjunction with standard electromagnetic analysis codes. To achieve this, first, an analytical sensitivity formula in the frequency domain is systematically derived by exploiting the augmented Lagrangian method, material derivative concept and adjoint variable method. Then unified program architecture integrating several engineering software packages into a design tool is proposed for optimum design of high-frequency devices. A 3-D dielectric resonator used in waveguide filters has been tested to prove the validity of the proposed method.

Parameter Extraction and Optimal Design of Spiral Inductor Using Evolution Strategy and Sensitivity

For precise electromagnetic (EM) field simulation of the spiral inductor, electric conductivity of the inductor substrate is determined by evolution strategy to match the Taiwan Semiconductor Manufacturing Company (TSMC) process. Based on this parameter, patterned ground shield (PGS) of an on-chip spiral inductor is designed using deterministic optimization method. The design parameters are lengths and widths of ground strips and widths of slots. For sensitivity analysis, approximate adjoint variable method is used. Significant increase in Q-factor is observed in final design while reduction of inductance is minimal. Spiral inductor with optimized PGS is used in input matching circuit of 2.45-GHz low noise amplifier (LNA), which shows improved noise figure characteristics compared to non-PGS case.