In the wireless communication realization process, the antenna is the essential component, and UHF RFID tag uses the radio wave to carry on the information transmission, the electric wave generation and the reception all need through the antenna realization.When the RFID tag enters the read-write antenna work area range, the RFID tag antenna will produce enough induction current, thus obtain the energy to be activated.
For RFID system, the antenna is the vital part, it is closely related to the system performance. At present, according to the antenna wire material, material structure and manufacturing process and other aspects of the difference, RFID tag antenna can be roughly divided into the following categories: etched antenna, printed antenna, wire-coiling antenna, add antenna, ceramic antenna, etc., the most commonly used antenna manufacturing process is the first three.
1. Etching method Etching method is also known as printing corrosion method, first in a base carrier covered with a layer of about 20mm thickness of copper or aluminium, in addition to the production of a screen printing plate of the antenna, with the screen printing of the resist printed on the surface of the copper or aluminium, and then protect the copper or aluminium below from corrosion, the rest of the corrosion agent is dissolved.
However, due to the chemical erosion reaction used in the etching process, there are problems with the long process flow and waste water, which can easily cause pollution to the environment, so the industry has been trying to find a better alternative.
2. Printed antennas The antenna circuit is printed or printed directly on top of the substrate with a special conductive ink or silver paste, more mature is gravure or screen printing. Screen printing saves costs to a certain extent, but its ink uses about 70% conductive silver paste with high silver content to obtain antennas between 15 and 20um, which is a thick film printing method and costly.
3. Coil-wound antennas The manufacturing process of copper wire coiling RFID tag antenna is usually done using automatic coiling machine, i.e. directly coiling on the base carrier film coated with insulating varnish and using low melting point baking varnish copper wire as the base material of RFID tag antenna, and finally using adhesive to mechanically fix the wire with the base material and coiling certain number of turns according to different frequency requirements.