| Summary: | 碩士 === 逢甲大學 === 通訊工程學系 === 105 === The main target of this article is to design circularly polarized (CP) antenna for radio frequency identification (RFID) reader. There are three types of Ultra-High-Frequency (UHF) CP antennas presented in this research. These antennas have been fabricated on FR4 substrate. With the aid of FR4 substrate, the realization of the antenna could be easier and lower the price.
The first antenna is designed for global band UHF RFID Reader Antenna. Through coplanar-waveguide feeding, the feeding strip is extended to the center of the ground notch. An L-type strip is added at the ground ring to improve the circularly polarized effect. By optimally tunning the two strips, the antenna can reach optimal performances and be used in UHF RFID. The overall size of the antenna is
100×100×1.6 〖mm〗^3. The operation frequency band is 830MHz to 1010MHz. It can cover global UHF RFID applications.
The second antenna is designed for Taiwan UHF RFID reader. However, the size is smaller than the past published articles. The feeding structure is an inverted-L monopole antenna. In addition, adding a strip at the ground can generate circular polarization. By increasing the ground patch size, the antenna can be tuned to specified frequency band that is 922MHz to 928MHz. The overall dimension is 87×50×1.6 〖mm〗^3.
The last antenna is also developed for Taiwan UHF RFID Reader Antenna. It has higher gain than other antennas. The gain of the antenna is 5dBic. The antenna has double-substrate structure. With the stereoscopic feeding strip between the ground and the radiator, the radiator generates circular polarization wave. The antenna can be operated in 914MHz to 928MHz. The overall volume of the antenna is 120×120×30 〖mm〗^3。
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