• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.41-47
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• 2009

In this paper, a band pass filter with a rejection band is proposed for UWB(Ultra Wide Band) communication system. First, low pass filter accessed cut off frequency of 10.2 GHz was designed using structure stepped impedance. And high pass filter accessed cut of frequency of 3.2 GHz was designed using parallel short-stub. There was implemented composite connection of designed low pass filter and high pass filter. The relative dielectric constant, the height, the loss tangent of the PCB substrate were ${\varepsilon}_r$=2.2, h=0.508 mm and loss tangent = 0.0009 respectively. The fabricated band pass filter shows a compact size of 3 cm. The fabricated band pass filter was characterized using 37169A VNA(Vector Network Analyzer). And measured result were obtained 7.5 GHz of bandwidth and -10 dB of return loss and -3 dB of insertion loss from pass band. The result of the research can be used for the UWB communications and MIC/MMIC, RFIC system.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.443-446
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• 2002

In this paper, we present a new design method for a square iris polarizer to be used in dual-band (Ka-band; 20.8 ~21.2 ㎓, 30.6~31 ㎓) antenna feeds. Principles of operation of a square iris polarizer, its design concepts and methods are proposed. Based on proposed methods, a Ka- band polarizer with -35 dB return loss and 0.3 dB axial ratio is designed using the commercial software HFSS.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.193-199
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• 2017

In the paper, a dual band-notched monopole antenna is proposed for 2.4 GHz WLAN (2.4 ~ 2.484 GHz) and UWB (3.1 ~ 10.6 GHz) applications. The 3.5 GHz WiMAX band notched characteristic is achived by a pair of L-shaped slots instead of the previous U-shaped slot on the center of the radiating patch, whereas the 7.5 GHz band notched characteristic is achived by C-shaped strip resonator placed near to the microstrip feed line. The measured impedance bandwidth (${\mid}S_{11}{\mid}{\leq}-10dB$) is 8.62 GHz (2.38 ~ 11 GHz) which is sufficient to cover 2.4 GHz WLAN and UWB band, while measured band-notched bandwidths for 3.5 GHz WiMAX and 7.5 GHz bnad are 1.13 GHz (3.15 ~ 4.28 GHz) and 800 MHz (7.2 ~ 8 GHz) respectively. In particular, it has been observed that antenna has a good omnidirectional radiation patterns and higher gain of 2.51 ~ 6.81 dBi over the entire frequency band of interest.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.355-362
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• 2015

In this study, we have fabricated 9.385[GHz] circulator that is composed of WR112 waveguide and Ferrite for X-band radar. For designing Ferrite, B/R mode(Below Resonance mode) was used and calculated the condition of 120 degree rotation of the electric field in Ferrite and calculated internal DC magnetic field and external DC magnetic field. Also, dielectric materials of the same shape with Ferrite was filled between two Ferrite for improving the performance of the circulator, including impedance matching, bandwidth, quality factor, insertion loss. To obtain optimum shape of the Ferrite and dielectric material, we used CST MWS. Simulation result of the circulator is that 1.02 : 1 VSWR, -40dB isolation, 0.2dB insertion loss and measurement result is that 1.03 : 1, -38dB, 1.2dB at 9.385[GHz]. We can get good agreement at isolation and VSWR, but insertion loss was 1 dB great than simulation result.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.665-669
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• 2018

In this paper, we design an antenna for LTE / Wi-Fi communication that operates in 2.65 GHz and 5 GHz band for small-sized broadband communication antenna that can be used in the sea. Microstrip patch antennas were chosen to improve the bandwidth. The slot width, length, and transmission line width were calculated using the theoretical formula for each step. In addition, we designed a microstrip antenna using CST Microwave Studio 2014 program that can design 3D. Simulation results show that the reflection lossis -12.712 dB at 2.65 GHz and -16.583 dB at 5 GHz. The gain was 1.738 dBi at 2.65 GHz and 3.284 dBi at 5 GHz. In this paper, we propose a dual-band antenna for LTE / Wi-Fi, which can be used in maritime environments, which is worse than terrestrial communication, because of differences in communication speed and communication stability compared with those used on land.

• Journal of IKEEE
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• v.27 no.1
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• pp.109-115
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• 2023

In this paper, we design and implement an Ultra-Wide Band (UWB, 3.1~10.6 GHz) antenna with 5G mobile communication (3.42~3.70 GHz) and Wireless Local Area Network (WLAN, 5.15~5.825 GHz) bands rejection characteristics. The proposed antenna consists of a planar radiation patch with two slots. The upper slot contributes to reject 5G mobile communication band and the lower slot contributes to reject WLAN band. The Voltage Standing Wave Ratio (VSWR) values of the proposed antenna show good performances in whole UWB band except for rejection bands based on VSWR 2.0. The proposed UWB antenna was simulated using High Frequency Struture Simulator (HFSS) by Ansoft. The simulated antenna showed dual rejection bands of 3.31~3.92 GHz and 5.04~5.90 GHz in UWB band, and measured antenna showed dual rejection bands of 3.35~3.97 GHz and 5.06~5.97 GHz. The largest VSWR values measured at each rejection band are 13.60 at 3.64 GHz and 10.25 at 5.52 GHz. The measured maximum gain is 5.31 dBi at 10.00 GHz. The lowest gains for the measured antenna at rejection bands are -8.73 dBi at 3.70 GHz and -4.36 dBi at 5.56 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.37-43
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• 2009

This paper describes a monolithic Darlington-cascade amplifier (DCA) operating at X-band, realized with a 0.35-micron SiGe bipolar process, which provides 45 GHz $f_T$. A conventional cascade amplifier was also designed on the same process and tested to establish a reference. Compared to the reference cascade amplifier, the proposed monolithic amplifier circuit exhibits an improved gain of 2.5 dB and improved output power 1-dB compression point of 5.2 dB with 72% wider bandwidth. Measurement results show 19.5 dB gain, 11.2 dBm 1-dB compression power, and 3.1 GHz bandwidth. These results demonstrate that the Darlington-cascade cell is an advantageous substitute to the conventional cascade amplifier.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.239-246
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• 2013

In this paper, a dual-band on-body antenna operating at MICS and ISM band for a wireless medical repeater system is proposed and the antenna performance including the human body effect is investigated. The designed dual-band antenna is comprised of a top patch for ISM band and bottom patch for MICS band. Simulation and measurement was carried out in order to analyze the effects of human body on antenna performance considering real use. The proposed antenna has required impedance bandwidth enough to cover both MICS and ISM bands. The measured peak gains were -12.47 dBi and 1.71 dBi at the each center frequency of MICS and ISM bands, respectively. Furthermore, the antenna has the maximum radiation directed toward the inside of the human body in the MICS band and directed toward the outside in the ISM band. In addition, the return loss property of the antenna is insensitive to human body effects so that the proposed antenna is well suited for the on-body wireless medical repeater system.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.179-185
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• 2019

In this paper, we have studied narrow-band analog pre-distortion linearization technique using UHF 400 MHz band 20 W power amplifier. The analog pre-distorter used the SC1894 radio frequency power amplifier linearizer(RFPAL) provided by MAXIM Corp and through the look-up table technique confirmed the intermodulation distortion(IMD) performance and the adjusted channel leakage ratio(ACLR) improvement for bandwidth below 1 MHz which does not operate on existing chips. In the 400 MHz (400 ~ 500 MHz) band, IMD performance and the ACLR improvement of up to 17.46 dB based on 1-channel offset and up to 16.6 dB based on 2-channel offset were confirmed. In the system requiring the same linearity, we confirmed power efficiency improvement of 12.41% at output power of over 40 W.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.416-422
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• 2007

In this paper, a broadband 2-way power divider which can be used from 20 MHz to 500 MHz in the V/UHF band is designed using transmission-line transformer and ferrite toroid. A 2:1 impedance transformer instead of the conventional 4:1 impedance transformer is realized and this 2:1 transformer is connected with the conventional bridge-type 2-way divider to form a 2-way power divider. Insertion loss of about 3.5 dB, isolation of less than -10 dB, and return loss of less than -10 dB in most band of interest are measured.