The general principle of operation of any RFID system is quite simple. There are always two main components in the system: it is a reader and an identifier (a map, a label, a key fob). The reader emits electromagnetic energy into the surrounding space. The identifier receives the signal from the reader and generates a response signal, which is received by the reader's antenna and processed by its electronic unit.
By the principle of the RFID system can be divided into passive and interactive. In a simpler passive system, the reader's radiation is constant in time (not modulated) and serves only as a power source for the identifier. Having obtained the required energy level, the identifier is turned on and modulates the radiation of the reader with its code, which is received by the reader. By this principle, most access control systems work, where you only need to get the serial number of the identifier. Systems used, for example, in logistics, work online. The reader in such a system emits modulated oscillations, that is, it forms a request. The identifier decrypts the request and, if necessary, generates an appropriate response.

Why does RFID technology conquer more and more widespread markets, penetrating the most diverse areas of activity where fast and reliable identification of items is required? Because it has a number of advantages, in particular:
RFID tags do not need contact or direct visibility;
RFID tags are read quickly and accurately (approaching 100% identification);
RFID can even be used in aggressive environments, and RFID tags can be read through dirt, paint, steam, water, plastic, wood;
passive RFID tags have virtually unlimited lifespan;
RFID tags carry a large amount of information and can be intelligent;
RFID tags are almost impossible to fake;
RFID tags can be not only for reading, but also for recording a sufficiently large amount of information.

Identification of containers and other group cargoes is relevant for their dispatch during transportation. RFID allows you to greatly simplify and automate the process of cargo management. The requirements for cargo identification systems are numerous. This is a significant (up to several meters) reading range of identifiers, providing anticollision (reading several tags at the same time), and the work of tags on metal surfaces. In addition, from the point of view of the organization of the technological process, it is advisable to use tags with the possibility of rewriting information so that certain states of the process can be quickly displayed in the cargo ID. To solve this problem, it is advisable to use passive systems in the range of 800-900 MHz with special design labels. For cargo handling, stationary readers with a range of up to 4 ... 5 meters can be used, as well as hand-held scanners, for example, based on a PDA. Such readers have a read range of up to 30 ... 50 centimeters, and if they are connected to the network (for example, using wireless technologies like Wi-Fi), they ensure the “online” operation of the system as a whole.