Chang-Fa Yang

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A miniaturized quadrature hybrid coupler, a rat-race coupler, and a 4 times 4 Butler matrix based on a newly proposed planar artificial transmission line are presented in this paper for application in ultra-high-frequency (UHF) radio-frequency identification (RFID) systems. This planar artificial transmission line is composed of microstrip quasi-lumped(More)
In this paper, a planar circular patch array antenna that features electric fields focused in the near-field zone for 2.4 GHz radio frequency identification (RFID) applications is presented. This array antenna is implemented by using six circular patch elements and a microstrip feeding network with a proper input phase for each element. The array antenna is(More)
Presents an integration of a shielded anechoic chamber environment for the spherical near-field antenna measurement purpose on developing the RFID static test system and provides critical characterization features for evaluating the RFID tag 3D operation performance requirements. The prototype system architecture for the static test system provides the(More)
Recent developments in the field of radio frequency technologies have led to numerous challenges in providing comprehensive performance for the next generation wireless networks. Meanwhile RFID as the one of important core technology in toward this future approach, have been implemented extensively for different kind applications. Those applications direct(More)
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