Jae-Hyeong Ko

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.

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 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.

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.

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.

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.

An Improved Distributed Equivalent Circuit Modeling for RF Components by Real-Coefficient AFS Technique

In this paper, a real-coefficient approach to Adaptive Frequency Sampling (AFS) technique is developed for efficient equivalent circuit modeling of RF components. This proposed method is advantageous than the vector fitting technique and the conventional AFS method in terms of fewer samples leading to a lower order of a rational function on a given data and to a direct conversion to an equivalent circuit for PSPICE(Personal Simulation Program with Integrated Circuit Emphsis) simulation, respectively. To validate the proposed method, the distributed equivalent circuit of a presented multi-layered RF low-pass filter is obtained using the proposed real-coefficient AFS, and then comparisons with EM simulation and circuit simulation for the device under consideration are achieved.

Design of LNA and Mixer for Ku-band Receiver

Abstract - The Ministry of Information-Communication assigned 18~19GHz frequency band for communication of cabins and platform to link between subway/train and its station. In this paper, we propose wireless transmission devices which are 2 stage hybrid low noise amplifier of 18GHz band and mixer for 18GHz as well to apply for RF receiver. We designed LNA to be noise matched its 1st stage and gain matched for 2nd stage and mixer using 180° hybrid coupler to suppress the spurious signal. The transistors of 18 GHz LNA and mixer are NE3210S01 of NEC and KMB-N51-1, respectively. As the result of simulation, we get 19.92dB gain and 2.06dB noise figure with LNA and 8.61dB conversion loss with mixer.Key Words : Low noise amplifier, 18GHz, Noise matching, Gain matching, Diode mixer, Coupler* 준 회 원 : 중앙대학교 전자전기공학부 석사**정 회 원 : 중앙대학교 전자전기공학부 박사과정†교신저자, 시니어회원 : 중앙대학교 전자전기공학부 교수E-mail : kimcaf2@cau.ac.kr 접수일자 : 2011년 10월 22일 최종완료 : 2011년 11월 25일 1. 서 론 최근 대도시의 교통난 해소를 위해 정부에서는 더 많은 대중교통의 이용을 장려하고 있다. 그러나 지하철 이용 승객이 증가함에 따라 지하철 화재 사고나 승객 추락사고 등과 같은 안전사고에 더욱 노출되어 된다. 특히 출, 퇴근 시간대에 많은 승객들이 지하철을 이용하면서 승강장과 객실은 많은 유동인구가 협소한 공간에 밀집해 있기 때문에 작은 안전사고부터 대형사고까지 이를 빠르게 대처할 수 있는 모니터링 시스템이 필요하다.따라서 기관실 및 역사에서 모니터를 통해 승강장과 객실 상황을 한눈에 파악하여 신속히 대처 할 수 있는 영상전송장치가 필요하다. 과거에는 영상 전송을 위한 유선 통신 장치가 주를 이루고 있었으며, 이는 지하라는 장소적인 제한과 고품질을 위한 비디오 케이블, 고가의 공사비 등의 예산적인 문제를 동반하고 있고 아날로그 기반의 통신 방식으로 저화질의 품질을 제공함으로써 경제적, 품질적으로 비효율적인 단점을 지니고 있다. 이러한 단점을 보완하기 위해 무선 통신망을 이용한 영상 및 화상을 통한 모니터링 통신 시스템이 개발 되고 있다.하지만 2.4GHz 대역의 WLAN기반의 시스템은 범용 주파수 대역을 사용하기 때문에 다른 무선통신 시스템에 대한 주파수 간섭에 취약하고 근거리 통신망(100m 이내)을 지원하기 때문에 지하철 역사 간의 구간에서는 통신이 제한되었다. 이를 위해 정보통신부에서는 지하철 및 열차 화상전송을 위해 18.86~19.92GHz 및 19.20~19.26GHz의 주파수 대역을 ‘안전 및 공공 목적을 위한 지하철(철도 포함)의 무선영상 전송장치’용으로 사용하기로 결정하였다[1]. 이는 기존의 WLAN에서 있던 주파수 간섭 및 단거리 통신에 대한 단점을 극복하고 장거리 통신이 가능하고 무선영상통신 뿐 아니라 다양한 부가 서비스 제공이 가능할 것으로 사료된다.본 논문에서는 열차/지하철의 객실 또는 승강장을 감시하기 위한 무선영상전송장치를 제안하고 영상전송을 위한 RF 모듈에 적용 가능한 18GHz 대역의 저잡음 증폭기 및 주파수 혼합기를 설계하였다. 제안한 RF 수신 중계기는 고이득 특성가져야 하며 이를 위해 설계한 18GHz 대역의 저잡음 증폭기는 잡음을 최소화 하며 이득을 최대화하기 위해 2단 하이브리드 증폭기 구조로 설계하였다. 또한, 주파수 혼합기는 10GHz 대역 이상에서 인접 주파수 의 불필요한 신호에 대한 억제를 위해 스퓨리어스 특성에 강하도록 연구 및 설계하였다. 3dB 커플러를 이용하여 주파수 혼합기에 들어가는 국부발진기 신호의 위상을 180°차로 입력하여 불요파 특성을 향상하였다. 이는 지하철 무선 영상 시스템에서 다수 채널에서 수신되는 영상신호 간의 간섭에 강인한 특징을 갖는다. 또한, 초고주파 대역에서도 구현이 간단하고 선형특성이 우수한 수동소자 방식으로 설계하였다.