Near-Field Rfid Antenna Design For The Internet Of Things Applications

Radio Frequency Identification (RFID) is an automatic non-contact identification technology, which exchanges data by RF signals. Its convenience and efficiency are leading the spreading of RFID applications. Now, In retail industry, item-level tagging applications have widely adopted Near-field RFID to identify. And antenna plays a key role in the overall RFID system and the RFID applications. In this paper, UHF near field antennas and UWB antenna have been researched.UHF near-field reader antenna concerns two key properties which are reading distance and far-field gain. Near-field Reader antenna can be seen as a circular loop. To achieve a better reading distance, we have to enlarge the loop. But it will cause the current along the loop fall to zero and reverse direction. This paper introduced a double-layer folded loop reader antenna for near-field RFID applications. By folding negative current into down layer, the current on the up layer is kept in phase and produces an even and strong Magnetic field. It works at866MHz and has a good bandwidth under the condition of S11<-10dB. The reading distance is90mm and far-field gain is less than0.45dBi.An Ultra-High Frequency near-field tag antenna is proposed for RFID applications. The antenna is consisted of two parts, metal covering area and the segmented line sections for near-field radiation. The proposed segmented line sections allow current along the loop to maintain in phase to achieve a strong and uniform magnetic field in the near-field region. The antenna is printed on copper-print paper with an overall size of150×58×1.12mm3. The antenna input impedance is conveniently matched to the complex conjugate of the RF IC chip impedance. In addition, the gain of the proposed tag antenna is less than0.14dB. The proposed anti-metal tag antenna could be adopted for item level anti-counterfeiting with110mm reading distance.UWB technology provides a new way to data transmission. The log-periodic antenna is a non-frequency-dependent antenna. It can meet the needs of UWB RFID system. In this paper, we introduce a log-periodic antenna with a wide bandwidth. It has a size of60×60×2mm3, with a bandwidth of1GHz～12GHz and a far-field gain of6dB.