AN3359

Impedance matching

Doc ID 018585 Rev 1

11/28

Figure 8.

Antenna's Standing Wave Ratio (SWR)

The following changes will affect the radiation impedance of the PCB antenna:

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slight board size variation

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metal shielding

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use of plastic cover

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presence of other components in proximity of the antenna

The best performance impedance matching circuitry will compensate these effects so that

for operating frequencies, the optimum 50 Ohm impedance is achieved.