• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.12-16
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• 2003

This paper presents a compensation method for a temperature-dependent gain tilt in L-band erbium-doped fiber amplifier using a voltage-controlled attenuator. The gain tilts in the L-band of 1570-1605 nm due to a temperature change have negative slopes, whereas they have positive slopes for the increasing optical input powers in a saturation region. The proposed method utilizes these opposite gain variations to compensate for the gain tilt over a wide range of temperature. While applying forty channels with a channel spacing of 100 GHz in the L-band and changing the ambient temperature from 0 to $50^{\circ}C$, the compensation method maintained the gain deviation within 1 dB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.3
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• pp.31-37
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• 2015

In this paper, newly proposed dual-band microstrip antennas using stacked inverted-L-shaped parasitic elements are presented for GPS $L_1(1.575GHz)$ and $L_2(1.227GHz)$ bands. For making dual band which has large interval, ${\lambda}/4$($L_1$ band) inverted-L-shaped parasitic elements were stacked at both side of radiation apertures on the half-wavelength($L_2$ band) patch antennas. The resonance in the parasitic elements occurs through coupling to the patch. Next, due to using circular polarization at GPS, ${\lambda}/4$($L_1$ band) inverted-L-shaped parasitic elements was stacked using sequential rotation technique on the patch and both side of the diagonal corners of the antenna were eliminated to make dual-band circular polarization. The designed circular polarized antenna's dimensions are $0.43{\lambda}L{\times}0.43{\lambda}L{\times}0.06{\lambda}L$ (${\lambda}L$ is the free-space wavelength at 1.227 GHz). Measured -10 dB bandwidths was 120 MHz(7.6%) and 82.5 MHz(6.7%) at GPS $L_1$ and $L_2$ bands. and 3 dB axial ration bandwidths are 172 MHz(10.9%) and 25 MHz(2.03%), respectively. All of these cover the respective required system bandwidths. Within each of the designed bands, broadside radiation patterns were observed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.104-109
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• 2012

In this paper, we propose a way to improve the quality of L-band wireless communication from unfriendly influential factors lying in the neighboring RF bands. The UHF-band system has resonator components and they generate harmonics as the spurious in the L-band. Therefore, a metamaterial CRLH bandpass filter is designed for the purpose of system miniaturization and smaller insertion loss, and its spurious phenomenon is observed in the frequency domain. And its harmonics in the L-band are suppressed by a compact bandstop filter whose equivalent circuit is newly developed. The design methodology is validated by the equivalent circuit to be compared with commercial full-wave EM software simulations, where the spurious is dropped by 20dB. Also, the advantage of the proposed design is presented by the comparison where our filter is much smaller than the conventional parallel edge coupled filter by over 50%, with excellent harmonic suppression.

• Journal of The Korean Astronomical Society
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• v.43 no.4
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• pp.123-133
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• 2010

In order to study properties of the pulsation in the infrared emission for long period variables, we collect and analyze the infrared observational data at L band for 12 OH/IR. The observation data cover about three decades including recent data from the ISO and Spitzer. We use the Marquardt-Levenberg algorithm to determine the pulsation period and amplitude for each star and compare them with results of previous investigations at infrared and radio bands. We obtain the relationship between the pulsation periods and the amplitudes at L band. Contrary to the results at K band, there is no difference of the trends in the short and long period regions of the period-luminosity relation at L band. This may be due to the molecular absorption effect at K band. The correlations among the L band parameters, IRAS [12-25] colors, and K band parameters may be explained as results of the dust shell parameters affected by the stellar pulsation. The large scatter of the correlation could be due to the existence of a distribution of central stars with various masses and pulsation modes.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.2
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• pp.345-354
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• 2024

In this paper, we propose a triple band WLAN antenna for Wi-Fi 6E band with DGS. The proposed antenna has the characteristics required frequency band and bandwidth by considering the interconnection of two strip lines and three areas on the ground place. The total substrate size is 31 mm (W) × 50 mm (L), thickness (h) 1.6 mm, and the dielectric constant is 4.4, which is made of 22 mm (W₆ + W₄ + W₅) × 43mm (L₁ + L₂ + L₃ + L₅) antenna size on the FR-4 substrate. From the fabrication and measurement results, bandwidths of 340 MHz (1.465 to 1.805 GHz) for 900 MHz band, 480 MHz (2.155 to 2.635 GHz) for 2.4 GHz band and 1950 MHz (4.975 to 6.925 GHz) for 5.0/6.0 GHz band were obtained on the basis of -10 dB. Also, gain and radiation pattern characteristics are measured and shown in the frequency triple band as required.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.176-179
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• 2005

The increasing demand for high density packaging technologies and the evolution to mixed digital and analogue devices has been the con-set of increasing research in thin film multi-layer technologies such as the passive components integration technology. In this paper, Cu and TaO thin film with RF sputtering was deposited for spiral inductor and MOM capacitor on the $SiO_2$/Si(100) substrate. MOM capacitor and spiral inductor were fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, important devices for mobile communication system. Based on the high-Q values of passive components, MOM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and 5 dB for a 900 MHz filter. This paper also discusses a analysis and practical design to thin-film L-C band pass filter.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.353-361
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• 2021

This paper presents the jamming effect on the L5 band of Global Navigation Satellite System (GNSS) by analyzing real data collected via measurement campaigns in Korea region. In fact, the L5 band is one of the dedicated bands for various satellite navigation systems such as Global Positioning System (GPS), Galileo, BeiDou (BDS), and Quasi Zenith Satellite System (QZSS). And this band is also allocated along with various systems used for aeronautical radio navigation systems (ARNS). Among ARNS, the Distance Measuring Equipment (DME) and the Tactical Air Navigation System (TACAN) are systems that transmit and receive strong power pulse signals, which may cause unintentional jamming in the reception of GNSS signals. In this paper, signals in the main lobe of GPS L5, Galileo E5a, BDS B2a, and QZSS L5 are collected in Korean region to confirm whether the jamming effect exists in the band. And then, the pulse blanking technique, which is a simple signal processing technique capable of responding to pulsed jamming, is applied to analyze the jamming effect of DME/TACAN on the L5 band.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.22-28
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• 2017

In modern electronic warfare, a variety of devices are being operated in the fields for the purposes of communication and surveillance. Therefore, if such devices work in the same band, interference may occur and affect each other. Regarding L-band in which various devices including radar systems are operating, interference from existing devices may affect new ones in the band. In this paper, we estimate a probability distribution of the interference environment in L-band from the selected measurement data, which is fundamental for the mathematical analysis. After selecting the candidates of probability distribution, we suggest the best one from the group. The results of this study are expected to be utilized as fundamental data for the mathematical approach to the L-band interference environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.705-708
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• 2004

The spatial variability of the L- and C- band large scale remotely sensed soil moisture data, obtained during tire Southern Great Plain 1999 (SGP'99), was characterized. The results demonstrate that soil moisture data using L-band show the break in statistical symmetry (multiscaling behavior) with the variation of scale of observation, which is similar to that of the soil property such as sand content. Also, soil moisture data using C-band show single scaling behavior with the variation of scale of observation, which Is similar to that of the vegetation condition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.615-618
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• 2006

The broadband power detector for direct- onversion Six-port output circuit was designed and implementaed in this paper. The power detector should linearly operated to produce the linear amplitude and phase signal fer input RF signal in required broadband. So, the power detector should be designed under conditions of matching circuit with low VSWR. The designed power detectors, which were implemented in L-band with 50 ohm matching and Ku-band with matching circuit and isolator, respectively, were evaluated in the performances.