NXP Semiconductors
AN11740
PN5180 Antenna design
AN11740
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Application note
COMPANY PUBLIC
Rev. 1.1 — 19 June 2018
345311
34 of 62
4.2.1.6 Assembly and measurement
After the first assembly the impedance measurement must be done, as shown in an
example in Fig 28.
(1) A simple 2-pin connector is soldered between TX1 and TX2 to simplify the impedance
measurement.
Fig 28. Impedance measurement example
The measurement result is shown in Fig 29. The circuit does not meet the requirements,
i.e. it needs to be re-tuned.
The measurement result is typically slightly different than the simulation result, since the
accuracy of the original antenna coil measurement is limited, and therefore the antenna
coil parameters in the simulation typically do not 100%ly reflect the real parameters. This
must be corrected – and then re-tuned in the next steps.
