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Search Results: 1 - 10 of 151377 matches for " Ji-Chyun Liu;Feng-Seng Huang;Ching-Pin Kuei;Chin-Yen Liu "
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Compact Dual-Mode Double Square-Loop Resonators for WLAN and Wimax Tri-Band Filter Design
Ji-Chyun Liu;Feng-Seng Huang;Ching-Pin Kuei;Chin-Yen Liu
PIER C , 2013, DOI: 10.2528/PIERC13012002
Abstract: The improved configurations with dual-mode double-square-loop resonators (DMDSLR) for tri-band application are proposed in this paper. Two sets of loops including double-square-loop and G-shaped loop are involved in the resonators. The resonant frequency equations related to DMDSLR geometries are introduced for simply designing tri-band bandpass filter (BPF). Resonant frequencies and transmission zeroes can be controlled by tuning the perimeter ratio of the square rings and the couples. To obtain lower insertion loss, higher out-of-band rejection level, wider bandwidth of tri-band, and compact applications, the miniaturized DMDSLR structure is designed. The effective design procedure is provided. The proposed filter is successfully simulated and measured. It can be applied to WLAN (2.45, 5.20 and 5.80 GHz) and WiMAX (3.50 GHz) systems.
A Dual-Mode Aperature-Coupled Stack Antenna for WLAN Dual-Band and Circular Polarization Applications
Ji-Chyun Liu;Bing-Hao Zeng;Chin-Yen Liu;Hui-Chi Wu;Chung-Chi Chang
PIER C , 2010, DOI: 10.2528/PIERC10100902
Abstract: A compact stack antenna consisting of square loop resonators, aperture couples, feed line and the perturbation for dual-band and circular polarization (CP) applications is proposed in this paper. This perturbation applies both dual-mode and orthogonal mode effects existing in the square loop resonator to present wide-band and CP characteristics simultaneously. The stack antenna presents the desired bands of 2.46 GHz with bandwidth (BW) = 160 MHz (6.58%) and 5.28 GHz with BW = 450 MHz (8.52%). The circular polarizations for dual-band are demonstrated with axial ratio (AR) spectrum and orthogonal modes. The proposed antenna is successfully simulated and measured with frequency responses, radiation patterns and current distributions.
Dual-Mode CPW-FED Double Square-Loop Resonators for WLAN and Wimax Tri-Band Design
Chin-Yen Liu;Bing-Hao Zeng;Ji-Chyun Liu;Chih-Chiang Chen;Dau-Chyrh Chang
PIER C , 2011, DOI: 10.2528/PIERC11070303
Abstract: An improved CPW-fed configurations with dual-mode double-square-ring resonators (DMDSRR) for tri-band application is proposed in this paper. The resonant frequency equations related to DMDSRR geometry are introduced for simply designing tri-band bandpass filter (BPF). Resonant frequencies and transmission zeroes can be controlled by tuning the perimeter ratio of the square rings. To obtain lower insertion loss, higher out-of-band rejection level and wider bandwidth of tri-band, the improved coplanar waveguide (CPW) fed and the step impedance resonator (SIR) and meander line dual-mode perturbations are designed. The effective design procedure is provided. The proposed filter is successfully simulated and measured. It can be applied to WLAN (2.45, 5.20 and 5.80 GHz) and WiMAX (3.50 GHz) systems.
Miniaturized Dual-Mode Resonators with Improved Double Square Loop and Inter-Digital Couple for WLAN Dual-Bands
Ji-Chyun Liu;Kuan-Dih Yeh;Chih-Chi Yen;Chin-Yen Liu;Bing-Hao Zeng;Chih-Chiang Chen
PIER C , 2011, DOI: 10.2528/PIERC11081006
Abstract: A novel dual-mode double square loop resonator (DMDSLR) for dual-band band-pass filter (BPF) is presented in this paper. The simple meander loop in DMDSLR is studied to improve the performance of the conventional DMDSLR. Significant size reductions over 33% are achieved. In addition, the designed meander-loop DMDSLR filter shows lower insertion loss (2.24 and 2.28 dB), higher rejection level (28/56 dB and 53/36 dB), wider bandwidth (about 8.5% and 28%) at the 2.47 and 5.47 GHz bands, respectively. Two transmission zeros are placed between the two pass-bands and result in a good isolation.
Miniaturized Dual-Mode Resonators with Minkowski-Island-Based Fractal Patch for WLAN Dual-Band Systems
Ji-Chyun Liu;Hsin-Hsiang Liu;Kuan-Dih Yeh;Chin-Yen Liu;Bing-Hao Zeng;Chih-Chiang Chen
PIER C , 2012, DOI: 10.2528/PIERC11111502
Abstract: The miniaturized dual-mode dual-band band-pass filters (BPF) using Minkowski-island-based (MIB) fractal patch resonators are proposed in this paper. The BPF is mainly formed by a square patch resonator in which a MIB fractal configuration with 2nd order iteration is embedded in the patch. By perturbation and inter-digital coupling, the wide-band and dual-band responses are obtained respectively. For miniaturized wide-band design, at 2.41 GHz central frequency it has good measured characteristics including the wide bandwidth of 2.26-2.56 GHz (3-dB fractional bandwidth of 12.4%), low insertion loss of 0.72 dB, high rejection level (-52.5/-44.9 dB), and a patch size reduction with 60.6%. For compact dual-band design, the proposed filter covers the required bandwidths for WLAN bands (2.20-2.96 GHz and 4.74-5.85 GHz). The patch size reduction of 78.1% is obtained. Two transmission zeros are placed between the two pass-bands and resulted in good isolation.
A Compact Size and Small Frequency Ratio CPW-FED Circular Slot Antenna for GPS/WLAN Dual-Band and Circular Polarizations
Chia-Yen Wei;Ji-Chyun Liu;Tian-Fu Hung;Sheau-Shong Bor;Chi Chiang Chen
PIER C , 2011, DOI: 10.2528/PIERC11050410
Abstract: This paper presents a novel dual-band circularly polarized CPW-fed circular slot antenna with two open-ground rings. The proposed antenna is constructed with two opened-ground rings facing in opposite directions and embedded in the circular slot, and the enhanced feed strip of CPW. By way of adjusting the relevant parameters, we can obtain the dual-band at 1.57 GHz and 2.46 GHz respectively. A smaller frequency ratio of 1.56 is presented. The measured -10 dB return loss impedance bandwidth are 380 MHz (24.68%) for 1.57 GHz band and 210 MHz (8.33%) for 2.46 GHz band. The measured -3 dB axial ratio bandwidth for 1.57 GHz and 2.46 GHz bands are 13.38% and 8.13%, the polarization of radiation patterns are RHCP and LHCP for each band and the antenna gain are 3.72 and 3.21 dBic respectively.
Endothelial [Ca2+]i is an integrating signal for the vascular tone in rat aortae
Tung-Yi Huang, Hsiun-ing Chen, Chin-Yen Liu, Chauying J Jen
BMC Physiology , 2001, DOI: 10.1186/1472-6793-1-5
Abstract: Receptor-dependent (acetylcholine) or independent (ionomycin) agonists caused immediate EC [Ca2+]i elevation followed by vasorelaxation in preparations pre-contracted with phenylephrine. Low doses of agonists induced small EC [Ca2+]i elevations (about 100 nmol/L) and concomitant half-maximal vasorelaxation. At high doses, agonists elevated EC [Ca2+]i to μmol/L range with little additional vasodilatation. When EC [Ca2+]i was plotted against the vasorelaxation, the curves were almost identical for both acetylcholine and ionomycin treatments, in the presence or absence of various endothelial autacoid inhibitors. Calcium-free solution reduced basal EC [Ca2+]i and induced a drastic vasoconstriction. Endothelial autacoid inhibitors reduced EC [Ca2+]i changes and abolished both agonist-induced vasodilatation and calcium-free solution-induced vessel contraction. When the EC [Ca2+]i was completely chelated by 40 μmol/L BAPTA, the acetylcholine-evoked vasorelaxation could be abolished as well. However, when the EC [Ca2+]i was partially chelated by 20 μmol/L BAPTA, the acetylcholine-evoked vasorelaxation was almost unaffected.These results indicate that vascular tone is modulated by subtle changes of EC [Ca2+]i level, which seems to serve as an integrating signal in both basal and stimulated states.Vascular endothelium plays an important role in controlling vascular tone by secreting a variety of endothelium-derived relaxing factors (endothelial autacoids), namely NO, prostacyclin (PGI2), and L-NNA/indomethacin-insensitive relaxing factor [1,2,3]. In response to various chemical and physical stimuli, an elevation of endothelial cytosolic free Ca2+ concentration (EC [Ca2+]i) followed by the activation of calcium-dependent enzymes/channels and the consequent production of endothelial autacoids [4]. Although EC [Ca2+]i appears to mediate the release of endothelial autacoids, the direct relationship between EC [Ca2+]i and vascular contractility in intact vessels remains to be esta
A High Attenuation Electromagnetic Pulse Protector with Gdt, Mov and Parallel Coupled BPF on High Thermal Conductivity Substrates
Ming-Jer Jeng;Atanu Das;Liann-Be Chang;Ching-Chi Lin;Yi-Cherng Ferng;Chien-Fu Shih;Sheng-You Liao;Shu-Tsun Chou;Ji-Chyun Liu;Lee Chow
PIER Letters , 2012, DOI: 10.2528/PIERL12041804
Abstract: An alternative approach for robust electromagnetic pulse (EMP) protection circuit was proposed by using a parallel coupled band-pass filter (BPF) with high thermal conductivity AlN substrate in between with a traditional gas discharge tube (GDT) and fast response metal oxide varistor (MOV). This proposed configuration can suppress slow as well as fast voltage surges. The fabricated BPF with a center frequency of 2.5 GHz on the high thermal conductive (180~200 W/m·K) AlN substrate could efficiently suppress high power over voltage surge. Through the purposed cascade protection configuration, it is observed that 6KV ESD fast introduced pulse (5 ns/50 ns) and 4 KV lightning surge pulse(1 us/50 us) were attenuated to 511V and 396 V, respectively, and that is capable to be applied to an EMP protection circuit in the front end of a linear amplifier applications.
Complementary Split Ring Resonators with Dual Mesh-Shaped Couplings and Defected Ground Structures for Wide Pass-Band and Stop-Band BPF Design
Ji-Chyun Liu;Hsieh-Chih Lin;Bing-Hao Zeng
PIER Letters , 2009, DOI: 10.2528/PIERL09060402
Abstract: Novel configurations of complementary split ring resonator (CSRR) with dual mesh-shaped couplings and defected ground structures (DGS) are introduced to design the high performance of wide pass-band and stop-band band pass filters (BPF). This paper presents a low insertion loss (-0.82 dB), symmetry and sharper transmission zero level (-51.88 dB), using effective DGS and alternative coupling for CSRR. The filter with center frequency at 1.92 GHz, pass-band from 1.21 GHz to 3.05 GHz (BW = 95.8%) and wider stop-band (extended to 4.2 below -20 dB rejection level) is designed and fabricated. Simulation and measured results including surface current distributions and frequency responses are presented and discussed.
An Inductive Self-Complementary Hilbert-Curve Antenn for UHF RFID Broadband and Circular Polarization Tags
Ji-Chyun Liu;Bing-Hao Zeng;Ivy Chen;Chung-Chi Chang;Dau-Chyrh Chang
PIER B , 2009, DOI: 10.2528/PIERB09072103
Abstract: A novel fractal tag antenna constructed with Hilbert-curve and self-complementary configuration is proposed for UHF RFID applications. The main aim of this paper is to merge the meander line and meandered-slot structure of the RFID tag antenna in order to obtain a good performance of compact, broadband, circular polarization and conjugate impedance matching. The tunable inductive and broadband (-10 dB BW = 115 MHz) characteristics of frequency responses and directivity (1.62 dBi) as well as circular polarization (-3dB AR BW = 315 MHz) of radiation patterns for 900 MHz are studied and presented.
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