• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.602-612
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• 2013

In this paper, a design and fabrication of miniaturized 5.3 GHz reflection type $360^{\circ}$ analog phase shifter with branch line coupler and $360^{\circ}$ variable reactance load. In order to miniaturize phase shifter, novel branch line coupler is proposed. The novel branch line coupler is miniaturized using transformation of transmission line to T and ${\pi}$ type equivalent circuit. The miniaturized branch line coupler has small size of above 50 % compared with conventional branch line coupler. For wide phase shift range, $360^{\circ}$ variable reactance load structure is adopted. Especially, the structure was improved for linear phase shift by adding transmission line which acts as an impedance transformer. The improved structure was miniaturized using the equivalent lumped-element of transmission line. The fabricated phase shifter with $15{\times}15mm^2$ shows wide phase shift of above $480^{\circ}$, the insertion loss of -4~-6 dB and the reflection loss of below -20 dB at 5.3 GHz under 0~10 V control voltage range.

• Journal of the Korea Convergence Society
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• v.2 no.2
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• pp.47-56
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• 2011

Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.25-32
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• 2021

In this paper, the Magneto-Electric(ME) dipole array antenna with dual-polarization in the X-Band is proposed and it is implemented and measured. The proposed array antenna is composed of 32 single ME dipole antenna and a Teflon PCB. 1 × 1 ME dipole antenna is implemented dual-polarization by radiating vertical polarization and horizontal polarization from two pairs of radiators. 2-port feeding structures are realized by lamination process using LTCC. And, each port independently feeds the radiator through a Γ-shaped feeding strip with isolation between ports. The Teflon PCB used in the antenna array has a 4-layer structure, and 2-port is fed through the top and bottom layers. The λ_g/4 transformer is applied to the transmission line of the Teflon PCB for impedance matching of the arrayed antenna and the Teflon PCB, and the optimal parameters are obtained through simulation. The measured maximum antenna gains of port 1 was 18.2 dBi, Cross-pol was 1.0 dBi. And the measured maximum antenna gains of port 1 was 18.1 dBi, Cross-pol was 3.2 dBi.