AN2972 datasheet(21/25 Pages) STMICROELECTRONICS

21 / 25 page

AN2972

From design to production

Doc ID 15629 Rev 6

21/25

From design to production

Designers should expect some difference between the theoretical and the real performance

of the antenna on the PCB in the end application.

Here are a few considerations:

System level validation

It is paramount to take great care when validating the antenna tuning for the various

application use cases, whether it be programming traceability information on the

manufacturing line, performing inventory of several end-products in the warehouse or

reading data (end user).

Different reader profiles would result in distinct performance levels on a given M24LRxx

board.

Figure 24. Application examples

Considerations on the actual system tuning frequency

Even though all readers transmit at 13.56 MHz, the optimal tuning frequency of the

M24LRxx antenna is not necessarily exactly 13.56 MHz.

Some mutual mechanisms such as detuning/coupling between the reader antenna and the

tag antenna may lead to an M24LRxx antenna with an optimum tuning frequency different

from 13.56 MHz.

A good example is ST’s reference antenna (gerber files available from www.st.com) whose

tuning frequency is 13.74 MHz ((a)) to provide the best performance with the Feig MR101

reader.

Using the method described in Section 2.5.3: Metal considerations.

ai17184

AN2972 Fiches technique(PDF) 21 Page - STMicroelectronics