In the practical application of RFID tags, it is often necessary to read a large number of tags at the same time, such as the inventory of the number of goods in the warehouse, the inventory of the number of books in the library, and the reading of dozens or even hundreds of goods tags on conveyor belts or pallets. For the situation of most goods being read, the probability of being successfully read is called the reading rate. Passive RFID tags are divided into low frequency (LF) tags, high frequency (HF) tags and ultrahigh frequency (UHF) tags. LF tags are mainly used in simple access control systems, and their reading distance is generally within 20 cm. HF tags, including NFC series, have good encryption and can be read at close range. Then there is only RFID UHF tag, which is a long-distance reading tag, and the reading distance can reach 2-8 meters, and UHF tag can have anti-collision function, and the reading speed is fast. UHF RFID tags are generally used when the reading distance is expected to be longer and the scanning range of radio waves is wider. Therefore, in the field of logistics and supply chain, UHF RFID technology is chosen worldwide. When reading multiple tags, the reader first inquires, and the tags respond to the reader's inquiries one after another. If there are multiple tags responding at the same time during the reading process, the reader will inquire again, and the inquired tags will be marked to make them "sleep", thereby preventing them from being read again. To improve the reading rate of multi-tags, the reading range and reading time can be extended, and the number of information exchanges between tags and readers can be increased. In addition, high-speed communication methods between readers and tags can also improve read rates.   In addition to the reading distance and scanning direction mentioned above, the reading rate will also be affected by many other factors. For example, the movement speed of the goods at the entrance and exit, the communication speed between the tag and the reader, the material of the pasted goods and the outer packaging, the way the goods are placed, the temperature and humidity of the environment, the height of the ceiling, and the influence between the reader and the reader, etc. Reading rate is also related to tag life. Of course, new labels generally have good performance, fast reading, and low rate of missed reading. However, if the labels are not used and stored properly, the lifespan of the labels may be shortened. For example, some labels are not resistant to light. If they are exposed to the sun for a long time, the service life of the labels will be relatively short, which requires regular replacement of the RFID labels. If the label is to be used outdoors, it is recommended to use a specific industrial label. The life expectancy of these tags will be longer. Special attention should be paid to the use of tags in metal environments, especially when tags will be used against metal surfaces, anti-metal tags are required. Otherwise, metal blocks a lot of radio frequency signals, and loopholes are often prone to occur.