• 한국군사과학기술학회지
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• 제15권4호
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• pp.450-457
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• 2012

In this paper, we designed low phase noise frequency synthesizer with compact size for High frequency band (Ku-band). The paper addresses merits and demerits of single loop and dual loop frequency synthesizer. The phase noise characteristics of the phase-locked loop frequency synthesizer were predicted based on the analysis for phase noise contribution of noise sources. The proposed model in this paper more accurately predicts the low phase noise frequency synthesizer with compact size for high frequency band.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.385-386
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• 2008

In this paper, a simple dual band filter chip is designed with 0603 case size using IPD technology. The dual-band filter achieves high frequency band at 2.5 GHz and low frequency band at 1.8 GHz. The insertion losses in high frequency band and low frequency band are -0.195 dB and -0.146 dB, respectively. The return losses in these bands are -22.7 dB and -22.8 dB, respectively. The simple dual-band filter based on SI-GaAs substrate is designed within die size of about 1.3 $mm^2$.

• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.233-237
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• 2017

In this paper, a dual-band high frequency (HF) and ultra-high frequency (UHF) radio-frequency identification (RFID) tag antenna is presented that operates in the 13.56 MHz band as well as in the 920 MHz band. A spiral coil along the edges of the antenna substrate is designed to handle the HF band, and a novel meander open complementary split ring resonator (MOCSRR) dipole antenna is utilized to generate the UHF band. The dual-band antenna is supported by a single-feeding port for mono-chip RFID applications. The antenna is fabricated using an FR4 substrate to verify theoretical and simulation designs, and it has compact dimensions of $80mm{\times}40mm{\times}0.8mm$. The proposed antenna also has an omnidirectional characteristic with a gain of approximately 1 dBi.

• Journal of electromagnetic engineering and science
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• 제16권3호
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• pp.164-168
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• 2016

A dual-band through-the-wall imaging radar receiver for a frequency-modulated continuous-wave radar system was designed and fabricated. The operating frequency bands of the receiver are S-band (2-4 GHz) and X-band (8-12 GHz). If the target is behind a wall, wall-reflected waves are rejected by a reconfigurable $G_m-C$ high-pass filter. The filter is designed using a high-order admittance synthesis method, and consists of transconductor circuits and capacitors. The cutoff frequency of the filter can be tuned by changing the reference current. The receiver system is fabricated on a printed circuit board using commercial devices. Measurements show 44.3 dB gain and 3.7 dB noise figure for the S-band input, and 58 dB gain and 3.02 dB noise figure for the X-band input. The cutoff frequency of the filter can be tuned from 0.7 MHz to 2.4 MHz.

• ETRI Journal
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• 제33권5호
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• pp.818-821
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• 2011

A D-band subharmonically-pumped resistive mixer has been designed, processed, and experimentally tested. The circuit is based on a $180^{\circ}$ power divider structure consisting of a Lange coupler followed by a ${\lambda}$/4 transmission line (at local oscillator (LO) frequency). This monolithic microwave integrated circuit (MMIC) has been realized in coplanar waveguide technology by using an InAlAs/InGaAs-based metamorphic high electron mobility transistor process with 100-nm gate length. The MMIC achieves a measured conversion loss between 12.5 dB and 16 dB in the radio frequency bandwidth from 120 GHz to 150 GHz with 4-dBm LO drive and an intermediate frequency of 100 MHz. The input 1-dB compression point and IIP3 were simulated to be 2 dBm and 13 dBm, respectively.

• 한국통신학회논문지
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• 제27권2B호
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• pp.151-159
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• 2002

주파수 도약(Frequency Hopping)시스템을 구현하기 위해서는 고속으로 도약 가능한 주파수 합성기의 개발이 필수적이다. X-band 휴대용 위성단말기는 약 500홉/초로 주파수 도약하는 대전자전 기능을 가진 단말기이다. 본 논문에서는 X-band 휴대용 위성단말기에 실장되는 초고속 주파수 합성기를 DDS Driven PLL 방식을 이용하여 설계 및 제작하였다. 제작된 주파수 합성기는 102.4MHz 국부 발진주파수에서 100KHz 주파수 간격으로 송신주파수 6600∼7100MHz, 수신주파수 6140∼6640MHz를 발생시키고 입력되는 주파수 정보에 따라 원하는 주파수를 15usec 이내로 생성하며 1KHz 오프셀 주파수에서 -754Bc의 위상 잡음 특성을 보였다.

• 한국멀티미디어학회논문지
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• 제25권8호
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• pp.1022-1037
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• 2022

It is important to develop a transducer that generates uniform output power through frequency control of the HIFU at 4 MHz frequency for the high intensity focused ultrasound (HIFU) skin diseases treatment. In this paper, a 4 MHz frequency band HIFU system for skin disease treatment was designed, manufactured and developed. In HIFU, even for the ultrasonic vibrator in the 4 MHz frequency band, the characteristics of the output power of the HIFU are different depending on the difference in the thickness of the PZT material. Through the development of a system amplifier, the sound output of the HIFU transducer was improved to more than 48 W and uniform output power control was possible. And, it is possible to control the output power even in a frequency band of 4.0 to 4.7 MHz, which is wider than 4.0 MHz, and shows the resonance frequency of the transducer. The maximum output power for each frequency was 49.969 W and the minimum value was 48.018 W. The maximum output power compared to the minimum output power is 49.969 W, which is uniform within 4.1%. It was confirmed that the output power of the HIFU through the amplifier can be uniformly controlled in the 4 MHz frequency band.

• International journal of advanced smart convergence
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• 제11권2호
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• pp.53-58
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• 2022

In this paper, w-band frequency synthesizer was developed for frequency-modulated continuous wave (FMCW) radar sensors. To achieve a small size and high performance, We designed and manufactured w-band MMIC chips such as up-converter one-chip, multiplier, DA (Drive Amplifier) MMIC(Monolithic Microwave Integrated Circuit), etc. And interposer technology was applied between the W-band multiplier and the DA MMIC chip. As a result, the measured phase noise was -106.10 dBc@1MHz offset, and the frequency switching time of the frequency synthesizer was less than 0.1 usec. Compared with the w-band frequency synthesizer using purchased chips, the developed frequency synthesizer showed better performance.

• 대한의용생체공학회:의공학회지
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• 제22권2호
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• pp.197-204
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• 2001

• 전기학회논문지P
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• 제59권1호
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• pp.24-28
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• 2010

This paper is presented on the antenna design for notepc platform. We present the antenna with combination of electric-magnetic radiator for dual-band Wireless Local Area Network (WLAN) service and a High Speed Downlink Packet Access (HSDPA) service. Due to the limited antenna space in notepc platform, the antennas for various wireless communication service should be located at a very small area. In this paper, the magnetic-type radiator works for high frequency band (1.7 - 2.1 GHz) application and the electric-type radiator works for low frequency band (820 - 960 MHz) application. This combination produces wide-band characteristics in the high frequency band. Simulation and experimental results of input impedance and gain characteristics of the proposed antenna are presented. There are good agreements between the simulated and measured S11 and gain values.