Details

<p>Acknowledgments xi</p> <p>Preface xiii</p> <p>Introduction xvii</p> <p><b>Part 1. Context 1</b></p> <p>Introduction to Part 1 3</p> <p><b>Chapter 1. Recap of the Constraints Governing the Design of Antennas for an NFC Device 5</b></p> <p>1.1. Normative constraints 6</p> <p>1.1.1. Uplink from initiator to targets 7</p> <p>1.1.2. Downlink from targets to initiator 8</p> <p>1.1.3. “Contactless” standards versus NFC device antennas 10</p> <p>1.1.4. Technologies 12</p> <p>1.1.5. “NFC Forum Devices” and “NFC Forum Tags” 12</p> <p>1.1.6. Modes of communication of an NFC Forum Device 14</p> <p>1.1.7. Role of an NFC Forum Device 16</p> <p>1.1.8. Beware of false advertising 17</p> <p>1.2. Regulatory constraints 17</p> <p>1.2.1. RF regulations 17</p> <p>1.3. Constraints on the NFC market 18</p> <p>1.4. Typological constraints of NFC 19</p> <p>1.4.1. Application consequences and their direct constraints 20</p> <p>1.5. Applicational constraints on antenna design 21</p> <p><b>Chapter 2. Introduction to and Recap of the Principles Employed in NFC 23</b></p> <p>2.1. The physical fundaments of “contactless” and NFC 23</p> <p>2.1.1. Phenomenon of propagation and radiation 23</p> <p>2.1.2. Classification of fields and spatial regions 24</p> <p>2.1.3. Spatial regions 24</p> <p>2.1.4. Far field: r >> λ/2π (Fraunhofer zone) 24</p> <p>2.1.5. Intermediary field: r approximately equal to λ (Fresnel zone) 25</p> <p>2.1.6. Near field: r << λ/2π (Rayleigh zone) … and by essence, the origin of the “NF – Near Field”, and hence NFC 25</p> <p>2.1.7. Remarks on contactless, RFID and NFC application 25</p> <p>2.2. The concept of NFC  27</p> <p>2.2.1. Biot–Savart law  28</p> <p>2.2.2. Field H at a point on the axis of a circular antenna 28</p> <p>2.2.3. Decrease in the field H as a function of “d” 31</p> <p>2.2.4. Field H at a point on the axis of a rectangular antenna 32</p> <p><b>Part 2. Methods and Designs for NFC Device Antennas 35</b></p> <p>Introduction to Part 2  37</p> <p><b>Chapter 3. “Initiator” Antennas: Detailed Calculations 41</b></p> <p>3.1. Introduction 41</p> <p>3.1.1. There are initiators … and there are initiators 41</p> <p>3.2. Design of an initiator antenna (without influence from the outside environment) 42</p> <p>3.2.1. Operating mode  43</p> <p>3.2.2. Instructive recap 45</p> <p>3.2.3. Choice of integrated circuit 54</p> <p>3.2.4. Legislational constraining aspects and EMC pollution 59</p> <p>3.2.5. EMC filtering 60</p> <p>3.2.6. Choice of target used and incidence of its H_threshold 73</p> <p>3.2.7. Determining the inductance value of the initiator antenna 75</p> <p>3.2.8. Simple antenna 82</p> <p>3.2.9. Matching circuit for the impedance of the antenna 88</p> <p>3.2.10. Calculating the current in the antenna coil of the initiator 93</p> <p>3.2.11. Summary and examples 96</p> <p>3.2.12. Simulations  98</p> <p>3.2.13. Value of the field H radiated by the antenna 100</p> <p>3.2.14. Calculation and value of the working distance 101</p> <p>3.3. Maximum quality coefficient Q of the initiator antenna 101</p> <p>3.3.1. Q and cutoff of the field 103</p> <p>3.3.2. Decrease in the ISO field  106</p> <p>3.3.3. Measuring Q in the application 108</p> <p>3.3.4. Measurement of the bandwidth in the application 109</p> <p>3.4. Brief handbook on the process of designing an antenna initiator 110</p> <p><b>Chapter 4. Examples of Applications of Initiator Antennas 113</b></p> <p>4.1. Large antennas 113</p> <p>4.1.1. Communication with a mono-NFC device in “card emulation – battery-assisted” mode 114</p> <p>4.1.2. Communication multi-NFC devices in “tag batteryless” mode 114</p> <p>4.2. Large antenna in mono-device 115</p> <p>4.2.1. Mechanical formats of the NFC device targets 115</p> <p>4.2.2. “Form factors” and sizes of antennas of the targets 115</p> <p>4.2.3. Application distances required for operation 116</p> <p>4.2.4. Estimation of the “loading effects” of the distance or working range 117</p> <p>4.2.5. Environment (copper, ferrite, battery, etc.) 117</p> <p>4.2.6. Several measures for illustrating our proposal 117</p> <p>4.2.7. H_d field necessary for the NFC device target 119</p> <p>4.2.8. H_0 necessary to create at the antenna level of the initiator 120</p> <p>4.2.9. Power P (in watts) 120</p> <p>4.2.10. Field H which must be produced by the initiator for a specific 120</p> <p>4.2.11. Definition of the initiator antenna: format of the “landing area” of the reader (where one puts the target) 121</p> <p>4.2.12. “System” considerations of the application 121</p> <p>4.2.13. Market integrated circuits for direct attack of the antenna 122</p> <p>4.2.14. Booster amplifiers 124</p> <p>4.2.15. Problem of the retro-modulation value 128</p> <p>4.3. Large antennas in multi-antennas 130</p> <p>4.3.1. In simultaneous mode (temporarily non-multiplexed) 130</p> <p>4.3.2. In multiplexed mode temporarily 133</p> <p>4.4. Large antennas in multi-devices 135</p> <p>4.4.1. Conclusions  137</p> <p>4.5. Other examples of initiator antennas  138</p> <p><b>Chapter 5. Antennas for Targets and Tags: Detailed Calculations 141</b></p> <p>5.1. Introduction: … there is a target and target  141</p> <p>5.2. NFC Forum Tags 141</p> <p>5.2.1. “Technology Subset”  142</p> <p>5.3. Introduction to problems of antenna targets/tags 146</p> <p>5.3.1. Tuning of the targets/tags 146</p> <p>5.3.2. The inductance L 146</p> <p>5.4. State-of-the-art of the antenna sizes  154</p> <p>5.4.1. Sizes of the target antennas 155</p> <p>5.4.2. Examples of applications of targets with antennas in ISO classes 157</p> <p>5.5. Technological aspect of the NFC targets and tags 165</p> <p>5.5.1. Data specific to integrated circuits for usage by NFC targets 165</p> <p>5.5.2. Data specific to the additional capacities 165</p> <p>5.5.3. Industrial data specific to antenna technology 165</p> <p>5.5.4. Technology at stake 166</p> <p>5.5.5. Estimation of the minimum number of antenna coils of the target to guarantee its remote power supply 171</p> <p><b>Chapter 6. Detailed Examples of Designs of Target Antennas 173</b></p> <p>6.1. Case of small antennas  173</p> <p>6.1.1. Examples in classes 4, 5, 6… or close by 174</p> <p>6.1.2. Example of design in class 5 175</p> <p>6.1.3. Example  180</p> <p>6.1.4. Example of design in class 6  182</p> <p>6.2. Case of very small antennas 189</p> <p>6.2.1. Example of design in classes 11, 12, 13  190</p> <p>6.3. Case of the large NFC target/tag antennas: format A4 203</p> <p>6.3.1. NFC bib number antennas for marathon and triathlon runners 203</p> <p>6.3.2. Technical properties required by the NFC target/tag  204</p> <p>6.4. Case of very large antennas targets: format A3  205</p> <p>6.4.1. Context and technical frame of the large antennas 205</p> <p>6.4.2. Retained concept 206</p> <p>6.4.3. Example of network with four antennas 213</p> <p>6.4.4. Simplification of the equation 216</p> <p><b>Chapter 7. The Initiator–Target Couple and Its Couplings  233</b></p> <p>7.1. Circuits and their couplings 234</p> <p>7.1.1. Mutual induction and mutual inductance 235</p> <p>7.1.2. Perfect mutual 237</p> <p>7.1.3. Non-perfect mutual 238</p> <p>7.1.4. Coupling coefficient “k” 242</p> <p>7.2. Tuned circuits coupled by mutual induction 244</p> <p>7.2.1. Why “almost”? 245</p> <p>7.2.2. Coupling index “n” 246</p> <p>7.2.3. In conclusion, an important point 247</p> <p>7.3. Identical coupled circuits, tuned to the same frequency 248</p> <p>7.3.1. Transfer function, A(􀈦) = V2/V1, in terms of the voltage of the secondary 250</p> <p>7.3.2. Transmission coefficient “Kt” 251</p> <p>7.3.3. In summary  252</p> <p>7.3.4. Operation in the vicinity of the resonance frequency f0 255</p> <p><b>Chapter 8. The Initiator–Target Couple and the Loading Effect 271</b></p> <p>8.1. Loading effect by coupling  271</p> <p>8.2. Coupled tuned antennas in terms of the primary current 272</p> <p>8.2.1. Primary (initiator) non-loaded (no target within the field) 273</p> <p>8.2.2. Primary (initiator) with a load (presence of target(s) in the field)  274</p> <p>8.2.3. Value of R2 in view of the environment 277</p> <p>8.3. Some food for thought 278</p> <p>8.4. Loading effect 281</p> <p>8.4.1. Definition and comments  281</p> <p>8.4.2. Parameters involved in the loading effect 282</p> <p>8.4.3. Variation of the working distance and thus of the coupling 285</p> <p>8.4.4. Magnetic coupling and its consequences 285</p> <p>8.4.5. Performances required by the initiator: loading effect on the value of the remote power supply to the target  286</p> <p>8.4.6. Quality of the emitted magnetic field 287</p> <p>8.4.7. Examples of coupling coefficients and loading effects  295</p> <p>8.4.8. “Shunt” circuit in NFC 302</p> <p>8.5. Appendix: how do we approach an NFC project? 307</p> <p>Conclusion 309</p> <p>Bibliography 317</p> <p>Index 319</p>

<p><b>Dominique Paret</b> is a consultant in radiofrequency identification, contactless technologies, NFC and indoor geolocalization. He teaches electronics and RFID in various engineering schools. He is also the author of several books on RFID technologies.</p>

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