Showing papers by "Dong-You Choi published in 2012"
TL;DR: In this article, the results of measurements of rain-induced attenuation in vertically polarized signals propagating at 12.25 GHz during certain rain events, which occurred in the rainy wet season of 2001 and 2007 at Yong-in, Korea, were presented.
Abstract: Quantitative analysis and prediction of radio attenuation is necessary in order to improve the reliability of satellite-earth communication links and for economically efficient design. For this reason, many countries have made efforts to develop their own rain attenuation prediction models that are suited to their rain environment. In this paper, we present the results of measurements of rain-induced attenuation in vertically polarized signals propagating at 12.25 GHz during certain rain events, which occurred in the rainy wet season of 2001 and 2007 at Yong-in, Korea. The rain attenuation over the link path was measured experimentally and compared with the attenuation obtained using the ITU-R model.
28 citations
24 Dec 2012
TL;DR: Among various option of miniaturization, a simple and effective method of obtaining a compact microstrip antenna is presented in this paper and the space-filling property of fractal geometry is explored for size reduction by incorporating Sierpinski Carpet on microstrip patch antenna.
Abstract: Among various option of miniaturization, a simple and effective method of obtaining a compact microstrip antenna is presented in this paper. The space-filling property of fractal geometry is explored for size reduction by incorporating Sierpinski Carpet on microstrip patch antenna. An edge-fed patch antenna is used as an initiator of all Sierpinski carpet iterations. The fractal iteration is performed up to 3rd order. The physical parameters of all four antennas are optimized to achieve the resonant frequency of 2.45 GHz which have many applications in short-range data communications such as in wireless sensors, radio frequency identification and personal area networking. The antennas are designed using finite element method based HFSS and their performances are demonstrated in terms of return loss, radiation pattern, smith chart, VSWR, and gain. Simulation results of Sierpinski Carpet iterations and their comparison with the generator shows significant size reduction, without affecting antenna performance such as reflection loss, impedance matching, and antenna gain.
17 citations
21 Feb 2012
TL;DR: This article will sketch some ideas for various application services by using e-business card on mobile environment to create a computing environment based on mobile.
Abstract: Today, all of the computing environments, resources, and application services on line will be move to a computing environment based on mobile in the future, especially mobile phone, it can be strong device not only supporting computing but being closely related to personal privacy. In this article, we will sketch some ideas for various application services by using e-business card on mobile environment.
2 citations
TL;DR: This paper mainly focuses on the simple design of an inset rectangular microstrip patch antenna to operate at a frequency of 2.45 GHz for rectenna design using an high frequency structure simulator to design the antenna dimensions and to determine its performance.
Abstract: In communication systems, there are various types of microstrip antenna that can be used for many applications. This paper mainly focuses on the simple design of an inset rectangular microstrip patch antenna to operate at a frequency of 2.45 GHz for rectenna design. The study involves using an high frequency structure simulator to design the antenna dimensions and to determine its performance. This antenna is based on a thickness of 1.6 mm flame retardant 4 (FR-4) substrate having a dielectric constant of approximately 4.7, an inset feed, and a ground plane. After simulation, the antenna performance characteristics such as its return loss, voltage standing wave ratio, gain, and radiation pattern were obtained and compared with the fabricated measured antenna.
1 citations
01 May 2012
TL;DR: In this paper, a simple design of inset rectangular micro strip patch antenna to operate at frequency of 2.45GHz for rectenna design is presented, which is based on a thickness of 1.6mm flame resistant 4 (FR-4) substrate with a dielectric constant of approximately 4.7.
Abstract: In communication systems, there are various types of micro strip antenna that can be used for many applications. This paper mainly focuses on the simple design of inset rectangular micro strip patch antenna to operate at frequency of 2.45GHz for rectenna design. The study involves using HFSS simulator to design the antenna dimensions and to determine its performance. This antenna is based on a thickness of 1.6mm Flame Retardant 4 (FR-4) substrate with a dielectric constant of approximately 4.7, inset feed and has a ground plane. After simulation, the antenna performance characteristics such as return loss, VSWR, gain, radiation pattern are obtained.