RFID applications in transport and production logistics are increasingly demanding high read ranges, also when in close proximity to liquids and metals. Conventional, foil-based RFID transponders (otherwise known as smart labels) are not suitable here. In deploying MID (Moulded Interconnect Device) technologies, Harting Mitronics has implemented three-dimensional antenna structures that, as passive transponders in the UHF range, attain a read distance of over 5m. At the same time, Ethernet connection is becoming more and more important for integration into the industrial environment. Luckily other Harting divisions can supply the suitable infrastructure for networking, including the necessary industrial switches and gateways.

Antennas

Truncated antenna designs with a directional response pattern must be used for passive RFID transponders in the UHF range (868MHz). Examples of the antenna principles that can be considered are patch antennas, inverted-F antennas and dipole antennas, each of which is arranged directly via a reflector.Selected thermoplastics have a low loss factor and a dielectric constant of 3, allowing use in applications at up to +180°C. The injection-moulded body made of thermoplastic materials is given a laser-structured metal coating as a three-dimensional conductive pattern. The transponder housing is also the circuit carrier, and the RFID chip is contacted by means if the flip-chip process. By sealing the housing with ultrasound welding, degrees of protection from IP54 to IP67 can be achieved.

In use

The assembled functional samples with various antenna principles show a high degree of correlation with the simulation results. The materials and manufacturing processes used offer a great deal of scope for design and application requirements.The function of passive RFID transponders has been verified in the UHF range, and the read distances achieved are around 6m. Field trials in transport logistics have also proceeded successfully, and more trials will follow with additional models.Compatibility with the local industrial Ethernet network infrastructure is vitally important for successfully integrating RFID technology into existing networks. This requires an analysis of the utilisation profiles of the corresponding systems and RFID readers, in order to facilitate seamless integration within the logistics chain.First the appropriate profile is drawn up by looking at the data quantities that arise in the logistics chain and the network section, using the cycle time of the reading system. This is conveyed to the logistics system in the form of standardised data packets, using the TCP/IP network protocol.For seamless integration into the Ethernet, Harting can work with reading-system manufacturers to offer appropriate infrastructure components. The individual configuration of the systems for the particular application is possible by using the standardised UDP protocol. This way, users are no longer tied to cumbersome programming with special equipment and proprietary solutions, but can instead work flexibly with the help of a standard web browser, and adjust all system parameters necessary for RFID operation. Existing RS-485/422 and RS-232 systems are easy to integrate directly by using the appropriate converter.Deployment of transponders allows a large number of applications in production automation, from process control to defense against counterfeit products in spare-parts management. However, not all solutions will realise the full potential that t RFID holds. Manufacturers need to coordinate the compatibility of the system components in customised projects and provide the active and passive infrastructure that will cope with IP67 levels of ruggedness.