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Jeong G.-T.,Inha University | Kim W.-S.,KEIT | Kwak K.-S.,Inha University
IEEE Antennas and Wireless Propagation Letters | Year: 2012

Design of a compact modified inverted-L antenna with a ground stub is proposed for Wi-Fi applications. With the ground stub structure, the impedance bandwidth for 2.45-GHz band enhances from 13.1% to 15.7%, and the impedance bandwidth for 5.2/5.8-GHz bands improves from 10.1% to 19.9%. The performances of the antenna with optimized parameters are characterized in terms of reflection coefficient, gain, and radiation pattern measurements in an anechoic chamber. The measured result satisfies Wi-Fi frequency specifications. © 2011 IEEE.

Oh S.-S.,Chosun University | Lee Y.-H.,ETRI | Kim W.-S.,KEIT
Microwave and Optical Technology Letters | Year: 2015

We propose a low-cost measurement technique of commercially available base-station antenna in a compact experimental setting, which may be considerably smaller than the far-field distance. An α-variable positioner was utilized with Fresnel-to-far-field transformation method. Compared with conventional near-field measurements, the technique described here allows for more rapid scanning and transformations. The experimental results show good agreement between the results measured at the far-field and that found using the Fresnel-to-far-field transformation. The experimental validity for commercial base-station antenna has been successfully shown for the first time as far as our knowledge, so that the proposed technique can be easily applied in small anechoic chambers, which are typically possessed by small-/medium-sized companies. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2617-2622, 2015.

Kim D.C.,ETRI | Kown O.-K.,ETRI | Kim H.-S.,ETRI | Kim K.S.,ETRI | And 8 more authors.
IEEE Photonics Technology Letters | Year: 2010

We report on the signal monitoring characteristics in a reflective semiconductor optical amplifier (RSOA) transistor outline can with a monitor-photodiode, thermoelectric cooler, and thermistor. Because of spatial hole-burning in the RSOA cavity, a front-side signal-monitoring module exhibits wider windows and better linearity in monitor current to signal power ratio (MCSPR) than a rear-side signal-monitoring module for current variations. In C-band, the average of the MCSPR is about 0.150 A/W and the MCSPR variation on wavelength is about ±0.038 A/W. © 2006 IEEE.

Yoon C.,Inha University | Lee W.-J.,Inha University | Kim W.-S.,KEIT | Lee H.-C.,Chodang University | Park H.-D.,Inha University
Microwave and Optical Technology Letters | Year: 2012

A compact and simple design of a printed antenna for ultra-wideband (UWB) application with band-notch characteristics are presented.The antenna size is 30 × 36 × 0.4 mm3 and operates over an extremely wide band of 2.82-13.95 GHz. The desired band-notched UWB operation can be obtained by choosing the size of the inverted L-slit. The proposed design consists of an inverted L-slit as the radiator and a coplanar ground plane. The proposed antenna has advantages of low cost, compact size, thin substrate, and easy design. The measured impedance bandwidth defined by VSWR ≤ 2 of 11.13 GHz (2.82-13.95 GHz), with the band-notched of 4.85-6.04 GHz, is obtained. Moreover, omnidirectional radiation patterns with appreciable gain across the operating band can be obtained. © 2011 Wiley Periodicals, Inc.

Yoon C.,Inha University | Hwang S.-G.,Inha University | Lee G.-C.,Inha University | Kim W.-S.,KEIT | And 2 more authors.
Microwave and Optical Technology Letters | Year: 2013

In this article, a broadband antenna for LTE, GSM, DCS, PCS, and WCDMA is proposed.The antenna consists of a T-shape strip and a shorted strip with capacitive coupling is excited. The capacitively coupled shorted strip shows resonance at the lower band, and the T-shape strip presents good matching at the higher band because the characteristics of input impedance are affected by the coupling. Moreover, by optimizing the dimensions of the L-shape strip, the total bandwidth of the antenna can be greatly improved. Copyright © 2013 Wiley Periodicals, Inc.

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