Design Constraints for NFC Devices

Dominique Paret

• Publisher: Wiley-ISTE
• Year: 2016
• Print ISBN: 9781848218840
• eBook ISBN: 9781119292210
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Mobile & Wireless Communications
• Index: Technology & Engineering

Near field communication (NFC) can appear to be a simple intuitive technology for exchanging data between close devices. In reality, these contactless structures that combine components and antennas must respect important and specific working constraints.

Illustrated by a number of detailed technological examples, this book discusses the multiple normative (ISO, CEN, NFC Forum, EMVCo, etc.) and regulatory (ERC, FCC, ETSI, radiofrequency, private and ecological pollution, etc.) constraints, as well as the applied, typological, functional, structural, environmental or interoperability constraints that a NFC device might face.

Design Constraints for NFC Devices also presents techniques that enable us to free ourselves from the technological constraints of current NFC operations encountered in banking, public transport, administration, automotive, industrial, communicating object and Internet of Things applications.

PART 1
Introduction to – and Reminders About – NFC

Introduction to Part 1

The first part of this book is divided into three chapters. In Chapter 1, the aim is to recap the operational principles of near-field communication (NFC) succinctly.

Chapters 2 and 3 describe the rigid structure of normative and regulatory constraints which apply to NFC elements, and primarily the design of their radiofrequency stages, their antennas and the connective problems directly associated therewith.

Although this first part of the book is an introduction, it encapsulates numerous technical points which are important to know in order to appreciate the application problems of today’s world and of these devices.

It is now for you, the readers, to discover all this for yourselves.

1
Recap of the Principles Employed in NFC

In order to be able to look at the idea of near-field communication (NFC) in its proper context, this chapter offers a summary of the main physical principles used in NFC, which must be remembered throughout this book.

1.1. The physical fundaments of “contactless” and NFC

To aid in the understanding of the specific problems of these applications, for readers who are unfamiliar with the technical details (or who need to refresh their memories), let us give a brief reminder here about radiofrequency (RF) communications, and describe unambiguously what the term NFC covers. It is physics; not marketing. Hence, it is necessary to review some of the theoretical and physical bases of the technical side of NFC.

1.1.1. Phenomenon of propagation and radiation

Let us look at some of the conclusions on the physical concept of propagation of an RF electromagnetic (EM) wave in the classic case of radiation of a simple “Hertzian doublet”. Later on, we will use this simple example to aid an examination of concrete cases of NFC.

1.1.2. Classification of fields and spatial regions

When studying the phenomenon of propagation and radiation of EM waves, the Maxwell equations tell us that the values of the radiated electric field E and magnetic field strength H depend notably on three main parameters:

1. – the variable time t;
2. – the variable distance r from the radiation source, defined in terms of 1/r, 1/r² and 1/r³. If one or more of these terms is negligible in comparison to the other(s), the equations may be simplified;
3. – the product kr, equal to: kr = 2π/λ.

1.1.3. Spatial regions

In the case of a very small antenna (whose sphere equivalent to the radiation source has a very small diameter), it is customary to define three spatial regions known, respectively, as the near-field, intermediary-field and far-field zones depending on the possible values of r in relation to the value of the wavelength λ at which the system operates – related to the value of r is greater or lesser than:

1.1.4. Far field: r >> λ/2π (Fraunhofer zone)

In the far field zone, the terms in 1/r² and 1/r³ present in the Maxwell equations become negligible, and the values of the fields E and H shrink in 1/r. This occurs when the distance r is greater than a few λ/2π. What happens at this point is that we move from a region of quasi-stationary waves to a region of wave propagation, and thus to a regime of radiated field. The electrical field E is predominant, and there can no longer be any magnetic coupling. Generally, in this zone, devices work by using the radiating field E, so use a dipole antenna.

1.1.5. Intermediary field: r approximately equal to λ (Fresnel zone)

In this spatial region, all the terms in 1/r, 1/r² and 1/r³ are equally preserved. Here, we are in the presence of a radiating near field, where the Fresnel component ...

Table of contents

• Cover
• Table of Contents
• Title
• Copyright
• Acknowledgements
• Preface Why and for Whom is this Book Written?
• Introduction
• PART 1: Introduction to – and Reminders About – NFC
• PART 2: Constraints Due to the Field of Applications of NFC
• PART 3: Applicational Constraints Needing to be Solved when Designing NFC Systems and their Antennas
• PART 4: Conformity and Interoperability Constraints
• Conclusion The “Near” and “Far” Future of NFC and its Antennas
• Bibliography
• Index
• End User License Agreement