New Design Of Dual-band RFID Antennas And Dual-band Power Dividers

RFID (Radio Frequency Identification) is an auto identification technique without touching. With the rapid development of RFID technology, it has been widely used, such as the Olympic Games tickets, ETC (electronic toll collection system), the second generation ID card and many other important occasions. In particular, as the rise of the Internet of Things, RFID technology will play a role of more importance. Compared with other automatic identification technologies, RFID has lots of advantages, such as longer recognition distance, higher recognition speed, more powerful penetrability, and better environmental adaptability. Dual-Frequency-RFID systems not only have the advantages above, but also can identify tags on two different bands, which would effectively save a lot of human and material resources.RFID reader antennas, which are used for sending and receiving radio signals, are an important component of RFID systems, and it determines performance of RFID systems. The antenna design to achieve the dual-frequency band is carried out by using the annular patch with curved and rectangular slots. And air is loaded between the substrate and the patch, which makes the antenna have a good directivity. At first, the initial valves of the antenna's structure parameters are set according to the reference. Then the simulation and optimization are done by using Ansoft HFSS software. The simulation results show that, the-10dB return loss bandwidth of the antenna is 10MHz at 915MHz band, and 20MHz at 2.45GHz band. The broadside gain is respectively 8.6dBi and 9.1dBi. Then we make the antenna in-kind. Finally, we test the antenna with vector network analyzer. The results are basically consistent with the simulation results, only the resonant frequency has a slight change.In addition, the paper also designed a dual-frequency equal power divider, and it applies in dual-frequency RFID systems, which is for 915MHz and 2.45GHz. The divider is presented by using a single allpass coupled lines section. The insertion phases of the single section at two resonant frequencies are different, and therefore can achieve a dual-band response. At first, we calculate the divider's structure parameters with the analysis method of odd-even model. Then the simulation and optimization are done by using ADS software. When result is satisfactory, we make it in-kind according to the layout, and test it with vector network analyzer. The test result shows that, in the desired bandwidth, return loss is less than -10dB, isolation is less than -15dB, insertion loss is more than-4dB, which can meet the requirements of dual-frequency RFID systems. And the volume of the divider is greatly reduced.