Search

A novel front-end structure for ultra-high-frequency RF identification reader is proposed. The proposed front-end consists of a balanced coupler and four-port feed antenna system. The proposed balanced coupler structure has high transmit/receiver isolation feature and good insensitivity to load variations. The proposed four-port feed antenna system is applied for removing the coupling among antennas, which deteriorates the isolation. The proposed system is numerically analyzed and verified experimentally as well. Index Terms--Antenna isolation, directional coupler, load impedance variation, ultra-high-frequency (UHF) RF identification (RFID).

A module integrated antenna with circular polarization for a mobile UHF radio frequency identification reader is presented. In the proposed design, a reader module using a hybrid assemble technique is directly integrated inside the antenna. In order to compensate the degraded radiation efficiency of the reader antenna due to the module integration, a quadruple inverted-f antenna (QIFA), a type of four-port antenna like QIFA, is used. For the compact four-port antenna, we analyze the optimum matching method considering both the reflection coefficient at each port and the mutual coupling among ports simultaneously to improve the performance of the proposed module integrated antenna. Experimental results show that the proposed module integrated antenna of size \ 80\times \ 80\times \ 11.2\ \ mm^3 with the shielded module is well matched, and has the peak gain of 3.3 dBic and the axial ratio under 2.5 dB. [ABSTRACT FROM AUTHOR]

This letter presents a reconfigurable 1 \times 4 power divider operated at 2.45 GHz. The proposed circuit has four power transmission states and is designed mathematically to satisfy matching conditions for each state. The experimental results for the transmission losses for each state are 1.2 dB \sim 1.9 dB while the isolations for non-path ports are greater than 25 dB and the reflection coefficients for each power transmission state are less than -20 dB at the target frequency. [ABSTRACT FROM PUBLISHER]