RFID Readers

The actual transponder is a tiny computer chip with an antenna. It can be integrated into various supports objects such as plastic cards, adhesive labels, plastic chips, etc.. Since an RFID tag is passive, that mean ist has no power supply, but is supplied by electromagnetic waves through the RFID reader with energy. Only then the communication is established with the RFID reader and the data exchange can take place.

Each transponder contains a globally unique identification number. Certain transponder types include additional data storage device that can be used for storing user-specific data. For example, objects that need to be checked regularly, can be equipped with a transponder and in the data memory of the transponder the last/next inspection date can be stored.

The RFID technology offers compared to barcode systems, among others the following advantages:

• Each transponder tag has a unique global identification number.
• The data collection is done without physical or visual contact.
• The simultaneous detection of multiple transponders (bulk reading) is possible.
• Transponder tags are insensitive to dirt and (with a correspondingly resistant carrier object) to any other damage.
• Certain transponder types allow the storage of additional data. These can also be changed.

Basic requirement for the selection of a transponder type and the RFID reader is a decision for one of the 3 frequency ranges, in which passive transponders can be operated (active transponders require their own power source and operate in the microwave frequency range from 2.4 to 2.5 GHz, 5.8 GHz and above (SHF)). The frequency ranges are not compatible with each other, RFID readers can not be converted to a different frequency range. Important criteria are range, compatibility with certain standards, cost of transponder and RFID reader and the scope of use of the transponder: Is there only the ID used or are there other data which has to be exchanged with the transponder tag?

Working Frequency 125/134 kHz (LF - Low Frequency)

• The range (depending on various factors, see below) is max. 0.5 m.
• Low transmission speed.
• LF-Systeme kommen mit hoher (Luft-)Feuchtigkeit und Metall zurecht und werden in vielfältigen Bauformen angeboten.
• Typical applications are: animal identification, reading objects with high water content, access control and vehicle immobilizers.

Working Frequency 13,56 MHz (HF - High Frequency)

• The range (depending on various factors, see below) is max. 0.5 m.
• Medium to high transmission speed.
• Typical applications include: access control, library management, ticketing (lifts, passenger and Events).

Working Frequency 860 – 960 MHz (UHF - Ultra High Frequency)

• The range (depending on various factors, see below) is about 3 bis 6 m.
• High transmission speed.
• Typical applications are: storage and logistics (for example, pallets).

Factors influencing the range
Bauform und Antenne des Transponder-Tags, sowie Antenne und Sendeleistung des RFID-Readers haben starken Einfluss auf die Reichweite. Der eigentliche Transponder-Chip ist nur wenige Quadrat-Millmeter groß. Die Größe des Transponder-Tags wird somit durch die Größe der Antenne bestimmt. Da es sich im Bereich LF-, HF- und UHF um passive Transponder handelt, die mittels elektromagnetischer Wellen mit Energie versorgt werden müssen, haben die Antennen von RFID-Reader sowie Transponder-Tag einen großen Einfluss auf die Reichweite. MDE-Geräte sind auf eine Stromversorgung mit Akkus angewiesen und daher für eine möglichst geringe Stromaufnahme ausgelegt. Mobile RFID-Reader/Writer erreichen daher oft nur geringere Reichweiten.

Design and antenna of the transponder tag, as well as antenna and transmit power of the RFID reader have strong influence on the range. The actual transponder chip is only a few square-Millmeter large. The size of the transponder tag is thus determined by the size of the antenna. Since it is passive transponder in the range LF, HF and UHF, which must be supplied by electromagnetic waves with energy, the antenna of the RFID reader and transponder tag have a major impact on the range. MDE devices rely on a power supply with batteries and therefore designed for the lowest possible power consumption. Mobile RFID Reader / Writer therefore often only reach lower ranges.

Transponder tag designs
Der Transponder-Chip und die Antenne können in Objekte unterschiedlicher Bauform und Material integriert werden. Verbreitet sind Etiketten, Smart-Cards, Gehäuse unterschiedlicher Bauform aus Kunsstoff oder Epoxidharz, Armbänder oder Schlüsselanhänger. Für die Anbringung auf metallischen Oberflächen gibt es spezielle On-Metal-Tags. Die Transponder können von außen am zu kennzeichnenden Objekt durch Kleben oder Schrauben angebracht werden oder auch direkt in dessen Material integriert werden. Die Wahl des Gehäusematerials bestimmt die Lesbarkeit sowie Beständigkeit des Transponders gegenüber Umwelteinflüssen wie mechanische Beanspruchung, Staub, Wasser, Kälte/Hitze, Chemikalien und damit auch dessen Sicherheit.

The transponder chip and the antenna can be integrated into objects of different shapes and materials. Widespread are labels, smart cards, housing different designs made of plastic or epoxy resin, bracelets or key chains. For attachment to metallic surfaces, there are special On-Metal Tags. The transponder can be mounted externally on to characterizing object by gluing or screwing or be integrated directly into the material. The choice of the housing material determines the readability and durability of the transponder to environmental influences such as mechanical stress, dust, water, cold / heat, chemicals and thus its safety.

RFID Reader/Writer
Grundentscheidung bei der Auswahl eines RFID-Reader/Writer ist die Mobilität. Soll die Erfassung an einem festen Ort erfolgen, empfiehlt sich die Installation eines stationäre Gerätes. Für die Erfassung von Objekte an unterschiedlichen Orten ist der Einsatz eines MDE-Gerätes mit RFID vonnöten. MDE-Geräte gibt es mit Kabel- oder Funkübertragung: USB, RS-232, WLAN, Bluetooth und Mobilfunk.

Fundamental decision when selecting an RFID reader/writer is mobility. To perform detection at a fixed location, the installation of a stationary device is recommended. For the detection of objects in different places, the use of an mobile data acquisition device with RFID is necessary. Mobile data acquisition devices are available with wired or wireless transmission: USB, RS-232, WLAN, Bluetooth and mobile.