• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1233-1237
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• 2011

Insertion loss, ripple, and return loss were -1.7093dB, 0.9162dB, and -24.762dB with Cellular Rx(824~849 MHz), -1.8021dB, 0.9615dB, and -22.258 with Tx(869~894 MHz), repectively. On the other hand, insertion loss, ripple, and return loss were -2.0149dB, 1.5163dB, and -34.046 dB with DCS Rx(1710~1785 MHz), -1.5894dB, 2.3742dB, and -33.058dB with Tx(1805~1880 MHz), respectively. In the particular, the attenuations in 5MHz edge of band width were -9.1399dB and -14.336dB with Cellular Rx, -7.0343dB and -5.2943dB with Cellualr Tx, respectively. The attenuations of DCS Rx from the relative Tx were -58.298dB and -65.644dB, respectively. On the other hand, those of DCS Tx from the relative Rx were -70.659dB and -50.488dB, respectively. From the aboved results, the dielectric filters for Celluar and DCS band with Isolator showed the good skirt and ripple characterics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.432-440
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• 2011

For the 4th generation mobile communication, LTE-advanced system needs the broad frequency band up to 100MHz for providing the data rate of maximum 1Gpbs. However, it is very difficult to secure the broad frequency band in the current frequency allocation situation. So, carrier aggregation was proposed as the solution, in which several fragmented frequency bands are used at the same time. Basically, multiple parallel receivers are required to get the information data from the different frequency bands but this conventional multi-chain receiver system is very inefficient. Therefore, in this paper, we like to study the single chain system that is able to receive the multi-band signals in a single receiver based on the time division multiplexing (TDM) reception method. This proposed TDM receiver efficiently manage to receive the multi-band signals in time domain and handle the baseband signals with one DSP board. However, the serious distortion could be generated by the sampling timing offset (STO) in the TDM-based system. Therefore, we like to analyze STO effects in the TDM-based system and propose a compensation method using estimated STO. Finally, it is shown by simulation that the proposed method is appropriate for the single chain receiver and show good compensation performance.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.33-38
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• 2013

In this paper, we present the design and measured performances of an dual-band Gysel power divider based on band-stop characteristic. After the Gysel divider is designed by lumped elements at single operating frequency, and then using filter conversion technique the lumped elements were changed a band-stop characteristic with dual-band characteristics. The features of this design method are that ${\lambda}/4$ transmission line by replacing lumped elements suppressed harmonic characteristics and also can reduce the size. To validate of the proposed power divider, the divider has been designed and measured at 880 MHz and 1650 MHz dual frequencies. The measured performances of the Gysel divider agree with prediction results at two frequencies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.93-97
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• 2022

Infrared scenes usually contain also spectral information which cannot be resolved using normal single-band infrared cameras. Multispectral infrared imaging cameras give access to the comprehensive information contained within infrared scenes. A Dual-band infrared Camera, a type of multispectral infrared imaging cameras, has the advantage of simple system. A Dual-band Infrared Camera gives access to the spectral information as wells as the temperature information within infrared scenes. Multispectral imaging generally increases the detection and identification performance of a Dual-band Infrared Camera. This paper describes a design of an infrared Camera using a Dual-band Infrared Detector to simultaneously receive infrared radiation from the medium-wave infrared/long-wave infrared(MWIR/LWIR) bands.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.167-172
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• 2006

In this paper, the 25W power amplifier for UHF band radio transceiver has been designed and realized. The power amplifier was composed of drive, power amplifier and control stages. Feedback topology and coaxial line baluns were used for wide band operation. The VDMOS, which has reliable performance for linearity and efficiency, was used for power device and designed to operate as push-pull amplification at Class AB Bias. The power amplifier designed in such a way was found to show stable AM modulation performance when voice signal was detected at the gate stage, with being designed and realized to meet output specifications of commercial air traffic control transmitter.

• The Journal of the Acoustical Society of Korea
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• v.24 no.1
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• pp.38-42
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• 2005

CMOS analog lowpass filters using speech signal bandwidth for a Asymmetrical Digital Subscriver Line(ADSL) modem are presented. Designed active lowpass filters are composed of the CMOS complementary high-swing cascode stage which can increase transconductance of an active element. As a result, their cutoff frequency are 138kHz and 1,100kHz respectively. A low-voltage high-swing cascode integrator which improved on a gain and unit gain frequency used to design the filters. The designed filters are verified by HSPICE simulation with the $0.251{\mu}m\;CMOS\;n-well$ Parameter and a single 2.5V power supply.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.348-355
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• 2006

In this paper, frequency multipliers used S-band transponder of the KOMPSAT 3 are designed and fabricated. In the transponder, 108 times multiplier which generate 1st LO signal(2008.8MHz) is comprised of the X9 frequency multiplier, 1st X2 multiplier, 2nd X2 multiplier and the last stage of the X3 frequency multiplier. As results, output power of 8.17 dBm at 2008.8MHz, the harmonic suppression of -56.67dBc, the bandwidth of 14MHz were measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1083-1088
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• 2002

A 5.8 GHz high gain MMIC amplifier was designed and fabricated. A HEMT was used as a active device and the spiral inductors and the metal insulator metal capacitors were used as the passive devices. To stabilize the high gain amplifier a RC feedback circuit was used. The amplifier has 4 stage and 31 dB measured gain. To prevent a oscillation by the coupling effects among the passive devices, the distance between the passive devices are made as far as possible. The via grounds were used to reduce the coupling effect between the input stage and the output stage.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.159-162
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• 1998

본 논문은 단일 채널에 다수의 정보 신호를 전송하기 위하여 사용하는 PCM/PSK/PM 변조 방식의 전송 신호 대역 특성에 대하여 기술하였다. 위성 관제 신호인 원격 명령 신호 및 원격 측정 신호의 변조 지수에 따라 전송에 필요한 대역폭과 위성과의 거리 측정 신호 전송에 필요한 전송 대역폭을 산출하며, 부 반송파 주파수 사용에 대한 관계를 고찰하였다. PCM/PSK/PM 변조 방식의 대역폭은 위상 변조 지수 1.2 rad 이하에서는 부 반송파 주파수와 전송 데이터 율에 비례한다. 2kbps 원격명령 데이터 전소에 필요한 원격 측정 신호를 위한 부 반송파는 131. 072kHz가 적합하다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.268-272
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• 2002

슬롯이 있는 직사각형 마이크로스트립 안테나의 이중주파수 동작 특성을 연구하였다. 마이크로스트립 안테나의 급전방식은 전자기적으로 결합된 단일 마이크로스트립 안테나이며, 패치구조는 직사각형 패치의 대각선 방향에 "ㄱ"형 슬롯을 대칭으로 배치시켰다. 본 논문에서 제안된 "ㄱ"형 슬롯의 장점으로는 패치의 크기를 줄이는 효과와 동시에 이중 대역의 주파수를 갖는 것으로 확인되었다. 제안된 마이크로스트립 안테나의 반사손실은 S11에서 -10 dB 기준으로 첫 번째 공진점 4.808 ㎓ 에서는 120 MHz의 대역폭을 가졌고, 두 번째 공진점 6.175 GHz 에서는 100 MHz의 대역폭을 가졌다.는 100 MHz의 대역폭을 가졌다.