Browsing by Author "Lo, Yu-Chen"

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Compact four bands hybrid filtering antenna using step impedance resonators and tuning stub transition structures
(2018-06-13)
Chen, Keng-Hsien
;
Lo, Yu-Chen
;
Lee, Yi-Shi
;
Wu, Sung-Jung
;
Tarng, Jenn-Hwan
A novel compact four bands hybrid filtering antenna composed of a hybrid radiator and a four bands bandpass filter is presented. The hybrid radiator is constructed using the micro-strip line fed, the square-ring and the T-stub near the ground plane. The proposed four bands bandpass filter is composed of two parts, one is two-step impedance resonators (SIRs) and the other is the tuning stub transition structure. With tuning stub transition structure, two SIRs effectively match to 50 hybrid radiator. Furthermore, the geometry of the proposed filter is U-shaped with the micro-strip fed around the hybrid radiator. The evolution of the hybrid radiator and the construction of the four bands bandpass filter using the two SIRs and the transitions are discussed in detail. The proposed filtering antenna not only possesses numerous operation bands with good band edge gain selectivity but also reduces the occupied size in the modern communication device. The overall size of the proposed filtering antenna is 33mmx36.4mmx0.508mm, and the operation frequencies are 1.8/2.45/3.5/5.2GHz bands for GSM1800/WLAN/WiMAX applications. The measured results agree with simulated outcomes.
Computations of the Signal-to-Noise Ratio for Medical X-Ray Imagers
(2014-08-01)
Lo, Yu-Chen
;
Huang, Kuan-Chieh
;
Yang, Kei-Hsiung
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光電系統研究所
;
影像與生醫光電研究所
If the signal in a medical X-ray imaging detector is formed by integrating the scintillation (or electrical) pulses, rather than by counting them, the signal-to-noise ratio is reduced by a factor which depends on the pulse height distribution. Formulas are expanded from Swank\'s publication to derive the signal-to-noise ratio for any given optical or electrical pulse-size distribution. A new quantity called noise-equivalent absorption is defined which bears a simple relationship to the signal-to-noise ratio of integrated X-ray imaging as the quantum absorption to the signal-to-noise ratio of photon-counting X-ray imaging.