**2. Near field communication magnetism – NFC and RFID**

NFC enables a subset of the Radio Frequency Identification (RFID) technology that works over a wide range of frequencies with three distinct bands — low, high, and ultra-high frequencies. The main difference between NFC and RFID technologies is their operating range. RFID operates in meters range, whereas NFC typically operates within three to five centimeters. All RFID's operate based on the same principle of one-way data transfer from the tag to the receiver and there is no power transfer the other way around [8, 9]. RFID is one of the oldest technologies that

*Near-Field Communications (NFC) for Wireless Power Transfer (WPT): An Overview DOI: http://dx.doi.org/10.5772/intechopen.96345*

#### **Figure 2.**

*Contactless transfer of data/signal between reader and tag at 13.56 MHz using NFC technology [16].*

utilize near field magnetic communication. In 1960, an electronic articles surveillance system (EAS) was the first commercial application of RFID, which utilized one-bit tag and was used to detect the presence or absence of the tag. Between 1970 to 1980, more work on RFID systems was conducted utilizing microwave and inductive systems and, in late 1970s, the size reduction of RFID's was accomplished using low-power complementary metal-oxide semiconductors (CMOS) logic circuits. After 1980, RFID applications became widespread such as tracking for animals, business, electronic toll collection, and automation, which was rapidly expanded with the development of personal computer (PC) technology. In 1990s, electronic toll collection systems were the first successful application of RFID technology worldwide [10]. Presently, RFID is utilized in various commercial areas such as automobile, agriculture, transport, medical system, payment cards, supply chain, tracking, identification application and short range interactions in the Internet of Things (IoT) [11, 12]. However, communications which require initialization at both ends (e.g., Peer-to-peer communications as discussed below) cannot be supported by RFID technology. NFC is a great solution to this shortcoming of RFID, which support peer-to-peer communications also.

NFC is a short-range half duplex communication technology which provide secure communication between devices in near field region. Near field communication, is a technology that allows two devices in close range to securely exchange data wirelessly. NFC is a short-range (< 10 cm) wireless connectivity technology that operates at high frequency (HF) range with low bandwidth of radio waves, mainly at 13.56 MHz [13]. NFC comprises of three basic components - an antenna, a reader, and a tag. A reader (transmitter) sends a signal at the standard NFC frequency of 13.56 MHz and the tag antenna receives and processes the interrogation signal, and responds with requested information back to the reader that is then interpreted and stored as the data within few centimeters at 13.56 MHz [14, 15]. **Figure 2** shows the transfer of data between reader and tag (card) at 13.56 MHz based on NFC technology [16].

From 2004 onwards, NFC has been utilized in various applications. Nokia, Apple/Google/Samsung pay transactions, wireless energy/data transmission and wireless key card entry are a few popular examples of this technology [17]. Though NFC tag is passive in nature, NFC can transfer data both ways. NFC technology supports varying data transmission rates, typical three rates are - 106, 212 and 424 Kbps [18]. There is another 848 Kbps rate also, but it is not in compliant with NFC standards.
