Active RFID (radio frequency identification) antenna capable of working in free space and on metal surface

Abstract

Disclosed is an active RFID (radio frequency identification) antenna capable of working in a free space and on a metal surface. The active RFID antenna capable of working in the free space and on the metal surface comprises a substrate, a micro strip electricity feed circuit carved in the front side of the substrate and a carving slot patch carved in the reverse side of the substrate, wherein a through hole used to feed electricity is formed in the substrate, the through hole is a nonmetal via hole, two ends of the micro strip electric feed circuit are open, an electricity feed point is located in the middle of the micro strip electric feed circuit, the carving slot patch is made of metal material, a short circuit slot and an open circuit slot which are vertical to each other are carved in the carving slot patch, the short circuit slot is formed in the middle of the carving slot patch, and the open circuit slot is formed in the edge of the carving slot patch. When the active RFID antenna is used in the free space, the micro strip electricity feed circuit stimulates the open circuit slot and obtains a dipole work pattern. When the active RFID antenna is used on the metal surface, the micro strip electricity feed circuit stimulates the short circuit slot, and obtains a patch work pattern. The active RFID antenna capable of working in the free space and on the metal surface is not provided with a floor, can be used in two environments of the free space and the metal surface, has good radiation characteristics in the two environments, and is concise and compact in structure, low in production cost, convenient to use on a large scale, and suitably used as the active RFID antenna.

Description

technical field [0001] The invention belongs to the technical field of antennas, and relates to an RFID antenna, in particular to an active RFID antenna which can work in free space and on metal surfaces. Background technique [0002] RFID technology was born in the 1940s and was initially used purely in the military field. Since the 1990s, it has been gradually promoted to be used in enterprises. In recent years, the application of RFID technology in identification, tracking and automatic data acquisition has made it popular and popularized in many service fields, such as goods distribution, commercial trade, manufacturing and logistics. A typical RFID system consists of three parts: the high-level system, the reader and the electronic tag. The electronic tag is generally composed of a tag antenna and a tag chip. The tag antenna has different working methods according to the way the tag obtains energy. The chip stores the target object The attribute, status and serial num...

AI Technical Summary

Problems solved by technology

Compared with active tags, passive tags are small in size, low in cost, and long in life, but the reading distance is relatively short. The reading distance of low-frequency and high-frequency tags is only tens of centimeters, and the farthest of ultra-high-frequency tags is only ten centimeters. the range of a few meters

Active tags are also called active tags. They have built-in batteries, use special radio frequency chips and regularly transmit signals actively, and have a long reading distance, which can be as far as hundreds of meters. The disadvantages are limited life, high cost, and large size. At present, it is generally used in the management of special occasions such as vehicles, shipping and mines.

[0004] The application environment of RFID tags is varied, and the material characteristics of the target surface to which the tag is attached may have an impact on the performance of the tag antenna. When placed on a metal surface, parasitic capacitance will be introduced, which will change the input impedance of the antenna, resulting in deterioration of antenna performance, shortened reading distance or even failure to read

In order to design a tag that can detect metal targets, there are four methods: (1) Reduce the influence of the metal boundary by adjusting the distance between the tag antenna and the metal surface, but this method increases the thickness of the antenna, and in some low profile It is difficult to implement the required occasions; (2) by adding a layer of absorbing material between the tag and the metal surface to reduce the impact of the metal target on the tag antenna, this method is too costly; (3) using the electromagnetic bandgap structure as a tag The dielectric plate of the antenna, this method will lead to a very complicated antenna structure; (4) Design the tag antenna as an antenna with its own ground structure such as a microstrip antenna, an inverted F antenna, etc.

Images