The design essentials and common steps of RFID antenna

The design goal of the electronic tag antenna is to transmit the maximum energy into and out of the tag chip, which requires careful design of the matching of the antenna and free space, as well as the matching of the antenna and the tag chip. When the operating frequency increases to the microwave band, the matching problem between the antenna and the electronic tag chip becomes more severe. For a long time, the development of the electronic tag antenna is based on the input impedance of 50 or 75. In RFID applications, the input impedance of the chip may be any value, and it is difficult to accurately test it in the working state. Lack of accurate parameters makes the design of the antenna difficult. achieve the best.

The design essentials and common steps of RFID Antenna

The design of the electronic tag antenna also faces many other difficulties, such as the corresponding small size requirements, low cost requirements, the shape and physical characteristics of the marked object, the distance between the electronic tag and the labeling object, the dielectric constant of the labeling object, metal The reflection requirements of the surface, the influence requirements of the local structure on the radiation mode, etc., all of which will affect the characteristics of the electronic tag antenna, are all problems faced by the electronic tag design.

The design of RFID Reader antenna

For short-range RFID systems (such as identification systems with 13.56MHz less than 10cm), the antenna is generally integrated with the reader; for long-distance RFID systems (such as identification systems with UHF frequency band greater than 3m), the antenna and the reader are often separated. structure, and the reader and the antenna are connected together through an impedance-matched coaxial cable. Due to the variety of structure, installation and use environment of readers, and the development of reader products towards miniaturization or even ultra-miniaturization, the design of reader antennas faces new challenges.

The reader antenna design requires low proFile, miniaturization and multi-band coverage. For the separate reader, it will also involve the design of the antenna array, the low efficiency and low gain caused by miniaturization, etc. These are currently the research topics of common concern at home and abroad. At present, we have begun to study the smart beam scanning antenna array applied by the reader. The reader can use the smart antenna to enable the system to perceive the electronic tags in the antenna coverage area according to a certain processing order, increase the coverage of the system, and enable the reader to read and write. Determine the target's azimuth, speed and direction information, with space sensing capabilities.

Design steps of RFID antenna

The performance of the RFID electronic tag antenna depends largely on the complex impedance of the chip. The complex impedance changes with frequency, so the antenna size and operating frequency limit the maximum achievable gain and bandwidth. In order to obtain the best tag performance, it is necessary Make compromises during design to meet design requirements. In the antenna design step, the reading range of the electronic tag must be closely monitored. When the tag composition changes or the performance of antennas with different materials and different frequencies is optimized, an adjustable antenna design is usually used to meet the deviation allowed by the design.

When designing an RFID antenna, first select the type of application and determine the required parameters of the electronic tag antenna; then determine the material used for the antenna according to the parameters of the electronic tag antenna, and determine the structure of the electronic tag antenna and the impedance after packaging; finally use The optimization method matches the packaged impedance with the antenna, and comprehensively simulates other parameters of the antenna to make the antenna meet the technical indicators, and uses a network analyzer to detect various indicators.

Due to the complex environment of many antennas, the analysis method of RFID antennas is also very complicated. The antennas are usually analyzed by electromagnetic models and simulation Tools. The typical electromagnetic model analysis methods of antennas are finite element method FEM, method of moments MOM and finite difference time domain method FDTD, etc. The simulation tool is very important to the design of the antenna. It is a fast and effective antenna design tool, and it is used more and more in the antenna technology at present. A typical antenna design method is to first model the antenna, then simulate the model, monitor the antenna range, antenna gain, and antenna impedance in the simulation, and use an optimization method to further adjust the design, and finally process and measure the antenna until it meets Require.