Browsing by Author "Lao, Ray-Rong"

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Design Methodology and Performance Evaluation of a Tapered Cell
(2013-06-01)
Shay, Wen-Tron
;
Hong, Wei-Ping
;
Lao, Ray-Rong
;
Tarng, Jenn-Hwan
;
傳播研究所
Tapered cells are used in the calibration of electric field (E-field) probes. However, the design methodology of tapered cells has not been publicly reported in detail. This paper introduces the structure of a tapered cell and proposes a theoretical model for characteristic impedance calculation. Based on this model and developed design rules, an impedance-matched tapered cell was constructed. The measured characteristic impedances and impedance distribution along the cell show favorable agreement with the design goals, verifying the accuracy of the design methodology. The field distributions were also measured. The results prove that the cell is useful for calibrating E-field probes.
High-sensitivity optically modulated scatterer for electromagnetic-field measurement
(2007-04-01)
Lao, Ray-Rong
;
Liang, Wen-Lie
;
Shay, Wen-Tron
;
Thompson, Richard P.
;
Dudley, Richard A.
The optically modulated-scatterer (OMS) technique is developed for electromagnetic-field-distribution measurement with minimum disturbance to the field under test. In this paper, an OMS with newly designed photoconductive-switching structure is proposed. The performances of the new OMS are evaluated with a monostatic-field-measurement system. Measurement results show that an improvement of 6 to 8 dB in sensitivity is achieved compared to previous OMS devices. The developed OMS was used in an electromagnetic-field-distribution mapping system to measure the field distribution in a cubic phantom radiated by a mobile phone. The results show the suitability of this OMS for specific-absorption-rate measurement application.
Optically Modulated Scatterer Technique for Radiation Pattern Measurement of Small Antennas and RFID Tags
(2009)
Lao, Ray-Rong
;
Shay, Wen-Tron
;
Hsu, Jimmy C.
;
Tarng, Jenn-Hwan
;
電信工程研究所
The optically modulated scatterer (OMS) technique is developed for the electromagnetic field distribution measurement with minimum disturbance to the field under test. In this letter, we present a novel method to measure the radiation pattern of unwired small dipole-like antennas such as radio frequency identification (RFID) tag antennas by OMS technique. The radiation pattern could be measured by this technique without any metallic feeding wire that would disturb the field pattern. The variation of the radiation pattern caused by the materials attached to an RFID tag antenna could also be evaluated with this technique.