Environment adaptive low-frequency RFID reader and resonance parameter adjusting method thereof

Abstract

The invention discloses an environment adaptive low-frequency RFID reader and a resonance parameter adjusting method thereof, and relates to the field of radio technologies. An impedance adjusting resistor and a resonance adjusting capacitor are added to a traditional circuit structure of a low-frequency RFID reader, a phase-locked loop driving source and an electronic switching circuit are switched automatically to match the capacitor and the resistor, and each time the reader is powered on, an internal MCU detects and adjusts the resonance parameter automatically. Thus, an antenna works in the optimal state, influence of environment on the low-frequency RFID reader is reduced, the environment is adapted to, and normal use of the low-frequency RFID reader is not influenced due to high switching speed of the electronic switching circuit.

Description

technical field [0001] The invention relates to the field of radio frequency technology, in particular to an environment-adaptive low-frequency RFID reader and a resonance parameter adjustment method thereof. Background technique [0002] Low-frequency RFID (Radio Frequency Identification, radio frequency identification) readers are widely used in daily life, such as access control, management of animals and plants, and the like. Please refer to figure 1 In the circuit diagram shown, the basic structure of the low-frequency RFID reader is a series resonant circuit composed of inductor L1, capacitor C1 and resistor R1. The inductor L1 is the antenna. The antenna L1 is both a transmitting antenna and a receiving antenna. Supply power to the low-frequency tags in the magnetic field, and also achieve the purpose of communication by analyzing the changes of the coupled magnetic field. [0003] Under normal circumstances, the matching of inductance L1, capacitor C1 and resistanc...

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Problems solved by technology

[0003] Under normal circumstances, the matching of inductance L1, capacitor C1 and resistance R1 has been adjusted to the optimal parameters when the low-frequency RFID reader is on the market. In the use of short-range low-frequency RFID readers, even slight changes in the user's environment will have little impact. Users can basically ignore this effect; but in the use of large-scale long-distance low-frequency RFID readers, environmental changes are often unexpected, such as metal railings, ferromagnetic media, etc. around, and the antenna in large long-distance low-frequency RFID readers The area is relatively large. Since the antenna itself is a purely inductive air-core coil, any metal or ferromagnetic medium placed within the antenna range will affect the inductance and AC impedance of the antenna. Therefore, the antenna in this type of reader is more susceptible to damage. The influence of other external media will destroy the adjusted resonance parameters when leaving the field, and affect the reading effect and normal use of the reader

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