Platform-insensitive antenna for RFID sensor tag in the UHF band

This paper presents a PIFA-type RFID sensor tag antenna with a noticeable feature, the platform-insensitive one. That is, a resonant frequency of the RFID sensor tag isn´t almost varied regardless of materials (plastics, woods and metals) for it to be stuck to and a gain variation is less than 1 dB at center frequency, 910 MHz. The designed antenna is a planar inverted-F antenna (PIFA) with the aperture coupling feeding. The impedance bandwidth and maximum read range of the sensor tag are measured on a plastic, wood and metal, respectively. The 3 dB return-loss bandwidth is about 15 MHz and maximum read range is each about 8.4 m, 8.9 m and 4.6 m on the wood, plastic and metal.