Si8440/1/2

18

Rev. 0.3

4.5. RF Radiated Emissions

The Si8440 family uses a RF carrier frequency of approximately 2.1 GHz. This will result in a small amount of

radiated emissions at this frequency and its harmonics. The radiation is not from the IC chip but due to a small

amount of RF energy driving the isolated ground planes which can act as a dipole antenna.

The unshielded Si8440 evaluation board passes FCC requirements. Table 10 shows measured emissions

compared to FCC requirements.

Radiated emissions can be reduced if the circuit board is enclosed in a shielded enclosure or if the PCB is a less

efficient antenna.

Table 10. Radiated Emissions

Frequency

(GHz)

Measured

(dBµV/m)

FCC Spec

(dBµV/m)

Compared

to Spec

(dB)

2.094

70.0

74.0

–4.0

2.168

68.3

74.0

–5.7

4.210

61.9

74.0

–12.1

4.337

60.7

74.0

–13.3

6.315

58.3

74.0

–15.7

6.505

60.7

74.0

–13.3

8.672

45.6

74.0

–28.4