Close-coupling cards: ISO/IEC 10536
In the ISO/IEC 10536 standard for close-coupling cards, this application is designated as ‘slot or surface operation’, which expresses the fact that in use the card must be inserted into a slot or laid on a marked surface of the terminal. The ISO/IEC 10536 standard , which bears the title ‘Identification Cards – Contactless Integrated Circuit(s) Cards’, consists of four parts:
–Part 1: Physical characteristics
–Part 2: Dimension and location of coupling areas
–Part 3: Electronic signals and reset procedures
–Part 4: Answer to reset and transmission protocols.
Parts 1 through 3 have already become international standards, while Part 4 is still in preparation. The important ingoing requirements for these standards were the following:
–extensive compatibility with ISO 7816
–operation with arbitrary orientation of the card to the reader
–transfer carrier frequency between 3 and 5 MHz
–bidirectional data transmission with inductive or capacitive coupling
–card power consumption less than 150 mW (adequate for microprocessor chips).
Part 1 of the standard defines the physical characteristics of the card. Essentially the same requirements are imposed as for contact-type smart cards, particularly with regard to bending and twisting. One difference is in the tolerance to electrostatic discharge. Since a contactless card does not require any conductive path between the card surface and the integrated circuit embedded in the card body, it is largely insensitive to damage from ESD. A test voltage of 10 kV is thus specified in the standard, compared with 1.5 kV for cards with contacts. Part 2 of the standard specifies the locations and dimensions of the coupling components. Since it was not possible to agree on a single method, both capacitive and inductive coupling components are defined in such a way that both can be implemented together in a single card or terminal. Examples of this are shown in Figures 3.78 and 3.79. The chosen arrangement is intended to ensure orientation independence with suitable excitation in the terminal. Part 3 of the standard, published in 1996, is the most important part to date. It describes the modulation methods to be used for capacitive and inductive data transmission, since agreement on a single method could not be achieved. A terminal that complies with the standard must therefore support both methods, and both methods may be implemented in a single card.

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Figure 3.78 The arrangement of the coupling components of a contactless smart card: (1) coupling coils in the card body, (2) capacitive coupling surfaces in the card body and (3) a set of contacts for the chip

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Figure 3.79 The arrangement of the coupling components in a terminal for contactless smart cards:(4) coupling coils in the terminal, (5) capacitive coupling surfaces in the terminal

Energy transfer
Energy is transferred by a sinusoidal alternating magnetic field with a frequency of 4.9152MHz, which passes through one or more inductive coupling surfaces, depending on how many coupling coils are present in the card. The terminal must generate all four fields. Alternating magnetic fields F1 and F2,which pass through areas H1and H2, have a mutual phase difference of 180 degrees, as do fields F3 and F4, which pass through areas H3 and H4. The phase difference between fields F1 and F3 and between F2 and F4 is 90 degrees. Each magnetic field is strong enough to transfer at least 150mWto the card. However, the card should not consume more than 200 mW. This complicated definition of the magnetic fields is necessary to achieve the same data transfer characteristics for four different card orientations, as explained below.

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Figure 3.80 Locations and sizes of the coupling areas in the contactless card and the terminal