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Thai Van Trinh,이병제,박태준,정창원 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6
An internal reconfgurable Dipole–Loop antenna array, covering the entire ultra-high frequency (UHF) band for ultra-high defnition television (UHD-TV) applications is presented. The internal antenna array is used to overcome the infuence of electromagnetic interference when integrating the antenna element inside the TV model and to increase the gain and reception rate of receiving signals for television broadcasting. The antenna array is designed based on the Dipole–Loop antenna elements, placing on substrate material PC-ABS (polycarbonate-acrylonitrile butadiene styrene: εr=3.5, tan δ=0.005) of the bezel frame in the TV model. By simultaneously switching PIN diodes with two ON/OFF states, the antenna array can be frequency reconfgured to achieve a wide operating bandwidth for UHF (470–771 MHz) band. The spacing between the antenna elements in the array at each mode is chosen as 0.5λ0 (λ0 represents the free space wavelength of the highest frequency in the operating band). The proposed antenna array is designed, fabricated, and tested for experimental verifcation. Measurement results show that the antenna array is good for high reception rate of UHD-TV applications, with a −6 dB impedance bandwidth of 51.6% (460‒780 MHz), covering the whole UHF band. The 3 dB gain bandwidths of 42.5% and 54.6% are obtained with peak realized gains of 9.6 dBi and 8.5 dBi for the horizontal and vertical polarizations, respectively. In addition, the diversity performance parameters are obtained and evaluated using the mean efective gains of the elements, and the diversity gain using both simulation and measurement results. It shows that the proposed antenna array can receive multi-side signals, applied in diversity and MIMO systems.
Thai Van Trinh,이병제,Chang Won Jung 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1
A compact wideband internal antenna based on an epsilon negative (ENG) zeroth-order resonator (ZOR) is proposed to operate in the ultra-high frequency (UHF) band (470–771 MHz) for ultra-high-defnition television (UHD-TV) applications. The antenna having a compact size of 9×220 mm2 is placed on the top edge of the 49-inch TV model. The bezel frame of the TV model is used as the substrate of the antenna. The antenna is fed by a coplanar waveguide with a ground plane (CPWG). A shorting plate was added to expand the ground plane of the CPWG structure to achieve resonance at lower frequencies. The ENG structure is formed by a meander line that generates zero-order resonances at higher frequencies in the UHF band. Based on analysis, the proposed antenna is fabricated and tested. The measurement results show that the refection coeffcient (S11) is under −6 dB in a wide frequency range from 440 to 910 MHz covering the entire UHF band. The fractional bandwidth is extended up to 69% with a peak gain of 4.8 dBi, and the average radiation efciency of the antenna is 75%.
Light-Induced Absorption and Holographic Recording in Pr:LiNbO3
Van-Thai Pham,임기수,D. S. Hamilton,Minh-Tuan Trinh,이선균 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.2I
With ultraviolet illumination, we have found a broad UV-induced absorption in the blue and some involvement of Pr ions in Pr:LiNbO3. Transient and stable absorption induced by UV illumination was analyzed at 457, 514, and 633 nm and could be explained by hole trap centers and iron ions. We also studied the effects of UV illumination and boundary conditions during holographic recording in the visible. In ultraviolet-gated short-circuit holographic recording, we obtained a high sensitivity and a high diffraction efficiency.