Koon-Tae Kim

Optimum Design of Wideband Bandpass Filter With CSRR-Loaded Transmission Line Using Evolution Strategy

In this paper, a planar wideband bandpass filter with complementary split-ring resonator (CSRR)-loaded transmission line is optimally designed taking into account a multi-regional objective function. Eight physical dimensions are set to be design parameters of the filter structure, and the Evolution Strategy (ES) algorithm is adopted to optimize the multi-parameter problem. The result shows that a simple gap capacitance model can make wideband bandpass filter and accomplish the design goal well with smaller size by the proposed optimization technique.

A Practical Approach to Robust Design of a RFID Triple-Band PIFA Structure

This paper presents a practical methodology of obtaining a robust optimal solution for a multi U-slot PIFA (Planar Inverted F-Antenna) structure with triple bands of 433 MHz, 912 MHz and 2.45 GHz. Using evolutionary strategy, a global optimum is first sought out in terms of the dimensions of the slots and shorting strip. Then, starting with the optimized values, Taguchi quality method is carried out in order to obtain a robust design of the antenna against the changes of uncontrollable factors such as material property and feed position. To prove the validity of the proposed method, the performance of the antenna is predicted by general-purpose electromagnetic software and also compared to experimental results.

Metamaterial CRLH Structure-based Balun for Common-Mode Current Indicator

We proposed a new PCB-type ‘common-mode current(I c ) and differential-mode current(I d ) detector’ working for fast detection of Ic and Id from the differential-mode signaling, with miniaturization effect and possibility of cheaper fabrication. In order to realize this device, we suggest a branch-line-coupler balun having a composite right- and left-handed(CRLH) one-layer microstrip phase-shifting line as compact as roughly λg/14. The presented balun obviously is different from the conventional bent-&-folded delay lines or slits on the ground for coupling the lines on the top and bottom dielectrics. As we connect the suggested balun output ports of the differential-mode signal lines via the through-port named U and coupled-port named L, I c and I d will appear at port Δ and port Σ of the present device, in order. The validity of the design scheme is verified by the circuit-and numerical electromagnetic analyses, and the dispersion curve proving the metamaterial characteristics of the geometry. Besides, the examples of the I c and I d indicator are observed as the even and odd modes in differential-mode signal feeding. Also, the proposed device is shown to be very compact, compared with the conventional structure.

Design of the miniaturized ultra-wide band (UWB) filter using the metamaterial characteristic

In this paper, a filter for the ultra-wide band (UWB) ranging 3GHz ~ 10.5GHz has been designed by taking the advantage of the metamaterial Composite Right & Left-Handed Transmission-line (CRLH-TL) with a Shorted Open Gap Ring Resonator (SOGRR) structure and an inter-digital line. In order to bring the remarkable improvement in an attempt to reduce the total metamaterial cell size, only one cell of the SOGRR with the inter-digital line is taken. This metamaterial filter will be shown to have the size of 15mm×15mm, the fractional bandwidth over 100%, the insertion loss much less than 1dB, and an acceptable return loss.

Robust optimum design of PIFA for RFID mobile dongle applications

A novel planar inverted F-antenna (PIFA) structure for a dongle-type RFID reader module with a resonant frequency of 920 MHz is proposed using a robust optimum design process. In order to take into account the robustness against noise factors, the Taguchi quality method is complemented to the evolutionary strategy optimization method. The validity of the proposed design process is verified through a noise test and comparisons of the computation and the experiment results.

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.

A Study on a Gain-Enhanced Antenna for Energy Harvesting using Adaptive Particle Swarm Optimization

In this paper, the adaptive particle swarm optimization (APSO) algorithm is employed to design a gain-enhanced antenna with a reflector for energy harvesting. We placed the reflector below the main radiating element. Its back-radiated field is reflected and added to the forward radiated field, which could increase the antenna gain. We adopt the adaptive particle swarm optimization (APSO) algorithm, which improves the speed of convergence with a high frequency solver. The result shows that performance of the optimized design successfully satisfied the design goal of the frequency band, gain and axial ratio.

An Optimal Design of Compact Ring-Slot Antenna for a Rectenna System With Numerical Manipulation

An improved design of a compact ring-slot type antenna for a rectenna system, which has superior and controllable property in size, directivity, and harmonics suppression is proposed. The conventional ring-slot antenna is modified with the slits and side-cuts to control the resonant frequency band, the suppression band, and the creation of circular polarization. Seven design parameters are selected from the primary research and optimized using the particle swarm optimization method with a numerically manipulated fitness function. The proposed antenna shows desirable performances in simulation and also in measurement with a reduced size.

An Optimal Design of a 19.05GHz High Gain 4X4 Array Antenna Using the Evolution Strategy

In this paper, we propose a optimal design using the Evolution Strategy of a high gain array antenna that have the resonant frequency of a 19.05GHz with 18.86GHz~19.26GHz bandwidth. The proposed array antenna structure is designed to be allocated equally electric power by microstrip patch power splitter. Thus the optimal array antenna with power splitter are determined by using an optimal design program based on the evolution strategy. To achieve this, an interface program between a commercial EM analysis tool and the optimal design program is constructed for implementing the evolution strategy technique that seeks a global optimum of the objective function through the iterative design process consisting of variation and reproduction. The simulation result of array antenna is confirmed that the Gain is 19.36 dBi at resonance frequency 19.05GHz.

Development of an Optimal Design Program for a Triple-Band PIFA Using the Evolution Strategy

In this paper, we deal with the development of an optimal design program for a triple-band PTFA(Planar Inverted-F Antenna) of 433 MHz, 912 MHz and 2.45 GHz by using evolution strategy. Generally, the resonance frequency of the PIFA is determined by the width and length of a U-type slot used. However the resonance frequencies of the multiple U slots are varied by the mutual effect of the slots. Thus the optimal width and length of U-type slots are determined by using an optimal design program based on the evolution strategy. To achieve this, an interface program between a commercial EM analysis tool and the optimal design program is constructed for implementing the evolution strategy technique that seeks a global optimum of the objective function through the iterative design process consisting of variation and reproduction. The resonance frequencies of the triple-band PIFA yielded by the optimal design program are 430 MHz, 910.5 MHz and 2.458 GHz that show a good agreement to the design target values.