Minimization of energy consumption in passive HF contactless and RFID systems

Green or environmental technologies are considered as one of the most significant topics for few years. Today, many people work on the development of new technologies based on energy harvesting or renewable energy. In this field of energy consumption optimization, a considerable work must be done on the consumption of current wireless communication systems as there are billions of wireless devices in the world and this continually grows up. Among all these wireless technologies, contactless technology is going to know a significant expansion as these standards must be used for all identification cards or payment cards. In such systems, the emitter uses magnetic waves to transmit power to the passive receiver. This principle needs a considerable amount of energy. The main problem of these systems is that the reader sends continually an RF field even if the card is not in its proximity. In this paper, we propose a new solution allowing the detection of a card without activating the RF field of the reader. The card presence is detected up to 10 cm in less than 3 μs with a minimal consumption of energy. This solution requires no modification of standards, of current contactless cards and can be added to a current reader for a low cost.