Far field Radio Frequency Identification Technologies

Radio Frequency Identification Technologies tags are usually consisted at the series of far field emissions. This field of emission grips to the electromagnetic waves which are usually propagating and transmitting in the direction of reader to the antenna which is attached with it. This smaller range type dipole antenna in  catches the power as a source and creates a high level of potential difference This high potential difference is of alternating type. This potential difference exists at the cross sectional arms of the dipole.

 The diode tries to rectify this high level potential difference. After rectifying the potential difference it is connected to the capacitor. This is the best source for accumulating the energy in the field of power electronics. Usually the far field technique is used by the designers for the scattering purpose. If the designers make an antenna having specific defined dimensions then it can be operated at a particular frequency. It requires  a lot of energy and operates at the high frequency. By the way normally the impedance does not matches with the frequency.

The antenna tries to push back or reflect the most of the power or energy.  This energy consists on the small waves. These waves are easily accessible to the reader. These electromagnetic waves are also easily accessible to the reader side. When the impedance of the antenna’s is changed with respect to time then the signal is deflected back to the reader side. In this time all the process is encoded and saved. Practically a detune type  antenna is suggested for this purpose.

It is obtained by putting a dipole transistor across its different ends. It is turned later by switching on or off. If we consider a simple and rough shape guide then it is necessary to use the frequency of higher value typically value of100 MHz near about. This high range frequency typically exists in the band of ultra high frequency. Its normal value is usually 2.45 GHz. Below this field the frequency normally exists into the coupling field.

In the far field type radio system the range is usually bounded with  the total amount of power. This total power reaches to the series of the tags.  Later than it can be received by the reader at the receiving end .This receiving signal is much sensitive as compared to the other broad band signal.

This return signal is usually very thin. The reason for its thickness is that it contains the attenuation due to which its final results are very poor as compared to the large signal. This attenuation is depending upon the inverse square law. The first attenuation exists due to electromagnetic series of waves. These electromagnetic waves are eliminated through the tag of the reader. When these waves are reflected then they travel back to the origin.

 So the returning power is usually is 1/r4 . In this the r shows the distance between the reader and tag. This all phenomenon is usually based upon the Moore’s law and this law is helpful in shrinking the process of tag and the reader. At the end of the process the energy decrease and it remains some microwatts at the end. But now the modern semiconductors are designed which can easily read the value of the increasing distance.

 Moreover more the radio receivers with modern technology has been developed which have the cheaper value and have the highest sensitivity.  In this way the signal is easily detected. this signal has the range value of the order of 100 dBm usually. A complex value for the far field reader is usually propagated 3m away from the series of the tags.