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Branch-LIne 하이브리드 3dB 결합기를 이용한 마이크로파 전송선로 전파수 판별기에 관한 연구
조홍구,이충웅 대한전자공학회 1985 전자공학회지 Vol.22 No.6
Branch-line 하이브리드 3dB 결합기에 λ/2-단락선로 스터브와 λ/4 -개방선로 스터브를 달결하여 입역임퍼던스 정합을 시키면서 스터브의 정재파를 이용하는 새로운 형연의 마이크로담대 선로 각도수 배별기의 이론을 제시하고 그것을 C-band에서 실현하였다. 실험적으로 중심주파수 4.940Hz에서 인별대역폭이 400MHz까지 선형성이 좋으며 return loss>15dB로서 사용할 수 있는 임피던스 정합특성을 가지는 인별기를 얻을 수 있음을 확인하였다. A new microwave transmission line frequency discriminator in MIC is described, which is composed of a branch-line hybrid 3dB coupler, a λ/2-short stub and a λ/4-opcn stub. It is experimentally verified that the discriminator is linear in a 400 MHz bandwidth at center frequency 4.94 GHz and has return loss more than 15dB in that range.
조홍구,박준석,안가람 국민대학교 생산기술연구소 2004 공학기술논문집 Vol.27 No.-
In this paper a DPDT(Double-Pole Double Through) switch with defected ground structure(DGS) is proposed. The equivalent circuit for the proposed switch structure is derived according to based on equivalent circuit of proposed DGS unit structure. The equivalent circuit parameters of DGS unit are extracted by using the circuit analysis method. The on/off operation of the proposed switch is obtained by varying the capacitance of the varactor diode at the defected ground plane. In the case of ON state, the insertion loss of the fabricated DPDT was shown under 1dB. And in OFF state, we found the rejection characteristic over 20dB at the designed frequency 2.45GHz. The experimental results show excellent insertion loss at on state and isolation at off state.
FDTD 알고리즘을 이용한 안테나의 방사특성 시뮬레이션
조홍구 국민대학교 생산기술연구소 2003 공학기술논문집 Vol.26 No.-
The finite difference time-domain(FDTD) method is one of the most widely used computational methods in electromagnetics. The basic FDTD approach of solving Maxwell's equations directly in the time domain via finite difference and time stepping has been reviewed. An FDTD algorithm programmed with the Matlab, a very inviting property of which is the wide varity of two- and three-dimensional visualization tools, simulates electromagnetic pulse as it radiates from the typical antennas such as dipole antenna, folded dipole antenna and Yagi-Uda antenna. A visualized time domain simulations of conventional well known antennas provide a much intuitive view of field radiation.
조홍구 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-
In this study, a real-time interface between transmission line modeling(TLM) and finite difference time domain(FDTD) algorithms has been reviewed and validated. A structure can be subdivided in an arbitrary way into connected TLM and FDTD subdomains that are updated simultaneously. In this way the specific advantages of both methods can be exploited when solving a given structure. The interface algorithms has been validated by identical structures with FDTD, and with a combination of FDTD and TLM. Two methods present identical numerical results for equal excitation, space, and time resolution.