From design to production

AN2972

22/25

Doc ID 15629 Rev 6

The read range varies depending on whether the M24LRxx board is read alone or stacked

with others (detuning effect). Figure 25 illustrates the detuning effect.

Figure 25. Detuning effect

The vicinity of another M24LRxx board may change the inductance dynamics. The boards

may couple with each other, leading to a resultant antenna resonant frequency different

from the individual one.

These are just examples of what may induce a difference between theory and real use

cases. They are meant to emphasize the need for real life validation of antenna designs.

PCB manufacturing process validation

The PCB fabrication parameters (such as the copper or epoxy layer thickness) have an

impact on the antenna inductance. Variations happen if the parameters of the PCB

fabrication process change or in case of a change of PCB supplier.

Departments such as quality, operations and manufacturing should therefore be made

aware of this.

Product packaging/housing considerations

The read range of the dual interface M24LRxx board can be greatly affected by the housing

of the final product.

The most obvious case is when a metallic housing is used. The product packaging then

behaves as a Faraday cage, preventing the reader energy and signal from attaining the dual

interface EEPROM device.

The housing might also influence the PCB antenna’s tuning frequency, which is why it is

always recommended to measure the RF performance of the application in the final product

configuration.