What is the principle of RFID reader?

Confucius said, "Knowing is knowing, not knowing is not knowing", and when I was asked about the RFID reading head in the first interview, I was really at a loss. I still learned slowly in my later work, and I learned that the original RFID reading head is the RFID reading and writing module, which is to encapsulate the reading head chip and communicate with the controller through serial port or C.

The RFID reader head transmits the identification signal and is equivalent to an antenna. According to the working frequency, the working frequency of the RFID system is the frequency used by the reader to send wireless signals, which can generally be divided into low frequency, high frequency, ultra-high frequency and microwave. The reader chip is the RF chip used in the RFID read/write module. The following editor will introduce the principle of RFID reading head for readers and friends?

How the RFID reader head works:

Radio frequency identification (RFID) is a non-contact automatic identification technology, the basic principle of which is to use radio frequency signals and spatial coupling (inductive or electromagnetic coupling) or radar reflection transmission characteristics to achieve automatic identification of identified objects.

The RFID reader communicates wirelessly with the RFID electronic tag through the antenna, and can read or write the tag identification code and memory data. A typical RFID read head consists of an RFID module (transmitter and receiver), a control unit, and a reader antenna.

Among them, electronic tags are also known as radio frequency tags, transponders, and data carriers; The reader is also known as the readout device, the scanner, the communicator, the reader (depending on whether the electronic tag can rewrite the data wirelessly). The spatial (non-contact) coupling of RF signals is realized between the electronic tag and the reader through the coupling element, and the energy transmission and data exchange are realized in the coupling channel according to the timing relationship.

There are two types of coupling of RF signals that occur between the reader and the transponder

1. Inductive coupling: The transformer model is coupled by a high-frequency alternating magnetic field in space, based on the law of electromagnetic induction.

2. Electromagnetic backscatter coupling: the radar principle model, the emitted electromagnetic waves are reflected after hitting the target, and at the same time carry back the target information, based on the spatial propagation law of electromagnetic waves.