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A new type of a compact tag antenna, which can be effectively mounted on metallic objects, is proposed for UHF band RFID systems. The proposed antenna consists of a simple microstrip path and feed line, and it is fabricated on a very thin (1.6 mm) subtrate compared with previous works. The impedance of the proposed antenna can be easily adjusted to match the various impedance values of tag chips by simply changing the length of the feed line only. The antenna is analyzed by simulations by Ansoft HFSS software, and the measured results based on backscattering method are provided. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 232–234, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23031

The simple and compact passive radio frequency identification (RFID) tag antenna mountable on metallic platforms is proposed. Without major modification of the radiating element and for easy impedance matching with various microchip impedances, an antenna is inductively coupled to a novel feeding structure placed on the side of a radiating patch. Using the commercial RFID system, radiation pattern and maximum distance are measured. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2446–2448, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21969

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CDA. In the range of 1.2-2.1 GHz, PAE of UBDA is over 20% and output power is up to 20 dBm. The improvement in output power becomes significant when the operating frequency increases. At 2.6 GHz, the output power of UBDA is 15.7 dBm which is 3.7-dB higher than that of the CDA. As shown in Figure 5, maximum PAE improvement occurs at 1.8 GHz at which the UBDA shows a 16.8% increase in PAE over the CDA. Figure 5 also shows that when the input power is smaller than 4 dBm, even the output power of the UBDA is similar to that of the CDA, satisfactory improvement in PAE can still be observed, and the saturation power is increased which provide a significant PAE improvement. CONCLUSIONAn unequal bias distributed power amplifier using discrete components has been presented. Experimental results show that the proposed UBDA provides a gain of 13.8 dB at 1.8 GHz with the operation frequency band from 0.8 to 2.6 GHz. It has also been shown that, by using the unequal bias technique, dummy load at the output ATL is eliminated with significant improvement in PAE and higher output power can be achieved through-out the operating frequency band. At the operating frequency of 1.8 GHz, a maximum improvement in PAE can be observed, which is three times higher than that of the optimized conventional DA.

A diversity antenna for a tri-band application is proposed and designed. The proposed diversity antenna consists of two wideband planar inverted-F antennas (PIFAs) and a suspended line between two PIFAs. The measured results show that the proposed antenna has a wide impedance bandwidth (37%) enough to serve a triple band (PCS, UMTS and WiMAX), a high radiation efficiency (> 50%), and a low correlation coefficient (< 0.2).