A RFID System consists of three main parts; a data carrier (also called a Tag or a Transponder), an Antenna and a Reader unit. The Antenna generates an electromagnetic field that energises a chip (IC-circuit) inside the Tag. The electromagnetic field is modulated by the Tag and the modulated signal is recovered by the Antenna and sent to the Reader unit for interpretation.   

Different systems use different frequency bands, low frequency (100-200kHz), medium frequency (13.56MHz) and high frequency (2.45GHz). We have specialised in the low-frequency area; 125kHz, 144kHz and 173kHz. But lately we have started to look at the new 13.56MHz frequency technology.  The different freqency bands have different qualities. There are three factors that are influenced by the frequency; the reading distance, the ability to penetrate materials and the ability to withstand electromagnetic background noice.  

There are two different types of Transponders.  
The read-only Tags has a pre-programmed unique code that are interpreted by the Reader unit. For an example a 64-bit code could after interpretation be presented as a 10 digit hexadecimalic code. The code in a read-only Tag can not be changed in any way.  

The read and write Tags have a unique number and a programmable memory. The Tag is programmed in the electromagnetic field and the information can be protected in different ways, typically with a password.   

The reading distance is depending on the type, size and shape of the Tag, the size and shape of the reading Antenna, the environmental conditions and the frequency. The reading distance can vary from a few millimetres to about 1,5 metres in the low frequency band, depending on the conditions above.