• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.434-444
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• 2002

본 논문에서는 기존의 RF 여파기가 대역 내에서만 정합이 되는 특성을 개선하여 대역 외에서도 50$\Omega$ 정합 특성을 가지는 여파기 설계 기술을 제안하였다. 대역 외에서 정합 시켜 주는 방법으로 결합기와 대역 통과 여파기로 구성된 Balance Type과 결합기와 대역 저지 여파기로 대역 통과 여파기 특성을 가지는 Reflection Type을 제시하여 그 특성을 확인하였다. 각각의 형태는 광대역 90도 3-㏈ 결합기를 사용한 것으로 결합기의 대역폭과 진폭 및 위상 오차에 따라 저지 대역에서의 정합 특성이 좌우되며, 이에 광대역의 3-㏈ 결합기를 설계 및 적용하여 광대역의 반사 손실 개선 효과를 얻을 수 있었다. 제작 결과 Balance type의 경우 1.2 GHz~2.6GHz까지 대역 내에서 -10㏈에서 -15 ㏈의 반사 손실 특성을 가지고 대역 저지 특성이 우수하며, Reflection type은 DC에서 3.3GHz까지 반사손실이 -15 ㏈ 내외로 광대역 정합 특성을 가진다. 특히, 저주파 반사 특성이 우수하여 저주파 발진 가능성이 큰 회로 설계에 유용하다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.924-929
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• 2009

In this paper, a dual-band MIMO antenna with a band stop matching circuit for next generation USB dongle application is proposed. The proposed multiband MIMO antenna consists of two dual-band PIFAs which provide wideband characteristics. In order to improve the isolation characteristic at the LTE(Long Term Evolution) band, a band stop matching circuit was inserted at the corner of each antenna element. The inserted band stop matching circuit is to suppress the surface current at the specific frequency band and to generate two additional resonances around 770 MHz for LTE band and near 830 MHz for digital communications network(DCN) service. The proposed MIMO antenna can cover LTE and DCN services, simultaneously.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.87-89
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• 2006

U-물류/유통, U-항만에 핵심적인 기술이 될 Ultra-Wide(UWB)통신을 위한 광대역 안테나를 설계, 개발하였다. 설계된 안테나는 UWB 주파수 대역인 3.1$^{\sim}$11.7GHz 대역에서 안테나 특성을 만족하고, IEEE 802-11a와HIPERLAN/2에 의해 사용이 제한된 5.15${\sim}$5.825GHz 대역에서 주파수 저지 대역을 가지기 위하여 U모양의 얇은 슬롯을 복사 패치 위에 구현 하였다. 제작한 안테나는 5${\sim}$595GHz 대역을 제외하고는 안테나의 특성을 만족한다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.219-222
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• 2002

본 논문에서는 이중 대역 소형 평면 패치 안테나를 이용하여 5.6GHz 대역과 5.8GHz 대역에서 동작하는 이중 대역 안테나를 제안하였다. 안테나의 격리도 특성을 최소화하기 위해 서로 다른 급전선 구조를 이용하였고, 급전부에 개방스터브를 사용하여 VSWR $\leq$2를 기준으로 5.48 GHz 대역과 5.87 GHz대역에서 각각 3.1%와 2.73% 이상의 대역폭을 얻었으며, 격리도 특성은 두 대역에서 평균적으로 -27㏈를 얻었다

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.777-784
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• 2004

In this paper, a new filter structure to improve frequency response characteristics in decimation filter using CIC(Cascaded Integrator-Comb) filters and half band filters is proposed. Conventional filters improve only passband characteristics, but we propose a new filter which can improve stop band and pass band characteristics simultaneously. Since proposed filter needs only two multiplication, additional implementation cost is not much. And overall linear phase characteristics are maintained since the proposed filter is also linear phase. Finally, filter coefficients quantization effects ate discussed after Verilog-HDL coding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.644-652
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• 2004

In this paper, we designed a cascaded microstrip lowpass filter using the lowpass filters previously proposed. The previously proposed lowpass filters have a ultra-wide stopband and prominent cutoff sharpness using the combined characteristics of slot and microstrip open stub, respectively, and they are catagorized into 2 types by the method that determining their passband characteristics. The first type is determined its passband characteristics by open stub characteristics and the second is by slot characteristics. By cascading these structures with impedance adjustment of each element, the deeper out-of-band rejection and the sharper skirt response were achieved. The fabricated cascaded lowpass filters have -3㏈ cutoff frequencies at 1.035㎓ and 1.286㎓ respectively and -20㏈ stopband is over 20㎓ for both structures.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.73-77
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• 2012

In this article, we designed a wide bandpass filter in order to apply microwave reflectometry for KSTAR. The proposed wide bandpass filter consists of a metamaterial structure which is to get a wide band, a lower insertion loss, and a high skirt. This is applied to VCO's output to enhance the linearity. A pass band is 18-28 GHz and the out of pass band is stopped over 20 dB. To confirm of the metamaterial, we suggest a dispersion diagram. The proposed filter in lower band and upper band of pass band is respectively a left handed and right handed characteristics. A group delay is below 0.5 ns.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.497-500
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• 2003

In this paper, a new filter structure to improve frequency response characteristics in CIC(Cascaded Integrator-Comb) decimation filters is proposed. Conventional filters improve passband characteristics, but they make worse slinging band characteristics. In this paper, we propose a new filter which is called IFOP(Interpolated Fourth-Order Polynomials). By using this proposed filter, passband droop and aliasing band attenuation are simultaneously improved. Since proposed filter needs only one multiplication computation is not much. And overall linear phase characteristics are maintained since the proposed filter is also linear phase. Finally, implementation cost of the proposed filter is compared with those of conventional filters.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.295-298
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• 2000

제품의 음질 특성과 관련된 주요 주파수 대역을 파악하기 위해 본 연구에서는 청소기 소리의 주파수 대역을 음성인식에 중요한 주파수 대역인 4개의 대역으로 나누고, 각 대역 성분을 직교배열표에 따라 가감한 16개의 소리를 만들었다 만들어진 소리에 대해 10명을 대상으로 4가지의 표현어로 Semantic Differential Method(SDM)로 주관적 평가를 하여, 청소기음의 주파수 특성과의 상관관계를 살펴보았다. 불쾌한 느낌과 관련이 깊은 주파수 대역은 고주파수 대역이었으며, 성능이 좋은 느낌을 주기 위해서는 저주파수 대역을 증가시키는 것 이 효과적이었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1053-1058
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• 2021

This paper presents the multi-band mixer which converts a X-, K- and Ka-band adaptively by adjusting the gate-bias voltage of an active device. The proposed mixer presented a conversion loss of -10 dB at -0.8 V gate-bias voltage for X-band, a conversion loss of -9 dB at -0.3 V gate-bias voltage for K-band and for Ka-band, a conversion loss of -7 dB at -0.2 V gate-bias voltage under the LO power of +6.0 dBm. The 1dB compression point (P1dB) is +0.5 dBm for all band.