What is RFID antenna? What types are there? How do they work?

RFID - radio frequency identification technology, is a non-contact radio frequency identification technology between tags and readers. It can directly identify specific targets and read and write related data within a certain range through radio signals. At present, this technology has been widely used in product traceability, intelligent logistics, intelligent warehousing, mobile payment, ticket anti-counterfeiting, etc.

1. Classification of RFID antennas:
The RFID system mainly includes three parts: electronic tags, induction antennas and read-write response equipment;
Among them, the antennas of the RFID system can be roughly divided into two categories: RFID electronic tag antennas and RFID reader antennas. These two types of antennas can also be subdivided into omnidirectional antennas and directional antennas according to their directivity. Besides, they aslo can be divided into Linear antennas and planar antennas accroding to appearance etc.

2. RFID antenna design principles:

(1) Miniaturize the antenna volume as much as possible;

(2) The antenna provides the largest possible signal to the chip;

(3) The directivity of the antenna coverage should be as large as possible;

(4) The polarization of the antenna can match the interrogation signal of the reader;

(5) The price of the antenna is as low as possible, and so on.

3. How DO RFID Antennas Work?

RFID antennas provide the means to communicate with transponders (RFID tags), and it provides the energy of exchange for the RFID tag.

When the RFID tag passes through the area that scans the antenna, it detects an activation signal from the antenna. This ""wakes up"" the RFID chip, which then transmits information on its microchip for pickup by the scanning antenna.

Also, active RFID tags have their own power source; the advantage of these tags is that the reader can go further and still receive the signal. Even though some of these devices have a lifespan of up to 10 years, they have a limited lifespan. However, passive RFID tags do not require batteries and can be smaller and have a virtually unlimited lifespan.

4. Manufacturing Process Type of RFID Antenna:

In order to adapt to the different requirements of RFID performance parameters in different application scenarios, various RFID antenna manufacturing processes have emerged. According to the wire material, material structure and manufacturing process, it can be roughly divided into the following categories: etched antennas, printed antennas, coiled antennas, additive antennas, ceramic antennas, etc.

(1) Etched Antenna:
Etched antennas are usually made of copper or aluminum, which is the mainstream manufacturing process of RFID antennas, with the highest market share and the most mature technology. It can be subdivided into: traditional etching method and precision etching method. In terms of material, it can be divided into: PET antenna, PI (polyimide) antenna, PCB antenna, etc. The etching method can be used in the mass production of electronic tags with 13.56MHz and UHF RFID. It has fine lines, low resistivity, It has the advantages of good weather resistance and stable signal. However, the shortcomings of this method are also obvious, such as cumbersome production procedures and low production capacity.

(2) Printed Antenna:
For printing antennas, the antenna circuit is directly printed or printed on the substrate with special conductive ink or silver paste. The more mature ones are gravure printing or silk screen printing. The biggest feature is that no etching is required, and there is no obvious pollution; the production speed is fast and the manufacturing cost is low. relatively low. The printing method is suitable for mass production of electronic tags of 13.56MHz and RFID ultra-high frequency bands. However, due to the large resistance of conductive ink or silver paste, and the large difference in performance of conductive materials, and with the passage of time, performance degradation will occur, especially in UHF antennas, there are still some problems with consistency and durability , which may be the main reason why printed antennas have not yet become mainstream antennas.

(3) Wire-wound antenna:
The copper wound antenna uses the coil winding method to wind the coil on the winding tool and fix it, and wind a certain number of turns according to different frequency requirements. The manufacture of this antenna is mainly used for low-frequency 125-134KMHZ and high-frequency 13.56MHZ electronic tags, and is rarely used in ultra-high frequency. Its biggest advantage is that it still performs well in the case of a small antenna area or volume. But its disadvantages: low production efficiency, high cost, high product thickness, not resistant to bending.

(4) Semi-Additive Antenna or Additive Antenna:
Addition process: First, a special catalytic ink is used to print the antenna pattern on the substrate, such as PET, PI, glass, ceramics and other media, and then copper is deposited on the substrate medium by electroplating to form Antenna circuit. Compared with the traditional printing silver paste process, this process has a more stable conductive copper layer, which has a greater improvement in performance consistency; compared with the etching process, it is more environmentally friendly and has a lower cost. However, the accuracy of its antenna is still limited by the accuracy of printing, and the stability of the antenna performance has not been verified in mass production.

(5) Ceramic Antenna:
The current ceramic antenna technology: choose ceramic substrate (alumina) as the base material and silver paste as the conductor body, print the antenna pattern on the substrate, and then sinter at high temperature to form the antenna circuit. The biggest advantage of this antenna process: stable performance and strong adaptability to the environment; the disadvantage is that the cost is too high and it is not easy to install. Label.

(6) Fragile Etched Anti-Transfer Antenna:
The fragile etched anti-transfer antenna is the same as the ordinary aluminum etched antenna in the antenna production process. The difference between the two is mainly the difference in the material structure. The fragile etched anti-transfer antenna is added between the aluminum thin layer and the PET substrate layer. A layer of special brittle material. The characteristic of the antenna is to realize the uniqueness of the electronic label, that is, "tear and destroy". When it is made into a label, it is attached to a flat and clean surface such as sealing, glass, plastic, carton packaging, etc., and then peeled off. The antenna of the label Or the face label cannot be completely lifted, in order to achieve the effect of destroying the label, so that the label cannot be recycled and reused.

At present, the most commonly used RFID antenna manufacturing processes mainly include coil winding method, etching method and printing method. However, with the development of conductive ink and printing technology, RFID printing antenna technology will be further popularized. This helps to reduce the cost of RFID tags, thereby lowering the application threshold of RFID, and promoting the implementation of RFID technology in all walks of life.