An overview of FCC regulations

AN4126

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Doc ID 023299 Rev 1

defined in FCC part 15.205, must comply with the radiated emission limits specified in FCC

part 15.209. For any 100 kHz bandwidths outside the frequency band of operation and

outside the restricted bands, the power must be at least 20 dB below that of the 100 kHz

bandwidth within the band that contains the highest level of the desired power.

Devices operating under part 15.249 are restricted to field strength emissions of the

fundamental of 50 mV/m and harmonic emissions of 500 µV/m measured at a distance of

3 m. This means approximately -1 dBm and -41 dBm respectively, when measured

conducted into a 50

Ωload. Radiated emission other than harmonics must be attenuated by

at least 50 dB below the level of the fundamental or to the general radiated emission limits in

the 15.209 section, whichever has the lesser attenuation.

Part 15.205 shows the bands where only spurious emissions are permitted. The field

strength of emissions appearing within these frequency bands must not exceed the limits

shown in part 15.209. The following tables show the restricted bands, as defined in part

15.205, and the radiated and conducted emission limits are defined in part 15.209.

Table 1.

Restricted bands defined in part 15.205

MHz

MHz

MHz

GHz

0.090 – 0.110

16.42 – 16.423

399.9 – 410

4.5 – 5.15

0.495 – 0.505

16.69475 – 16.69525

608 – 614

5.35 – 5.46

2.1735 – 2.1905

16.80425 – 16.80475

960 – 1240

7.25 – 7.75

4.125 – 4.128

25.5 – 25.67

1300 – 1427

8.025 – 8.5

4.17725 – 4.17775

37.5 – 38.25

1435 – 1626.5

9.0 – 9.2

4.20725 – 4.20775

73 – 74.6

1645.5 – 1646.5

9.3 – 9.5

6.215 – 6.218

74.8 – 75.2

1660 – 1710

10.6 – 12.7

6.26775 – 6.26825

108 – 121.94

1718.8 – 1722.2

13.25 – 13.4

6.31175 – 6.31225

123 – 138

2200 – 2300

14.47 – 14.5

8.291 – 8.294

149.9 – 150.05

2310 – 2390

15.35 – 16.2

8.362 – 8.366

156.52475 – 156.52525

2483.5 – 2500

17.7 – 21.4

8.37625 – 8.38675

156.7 – 156.9

2690 – 2900

22.01 – 23.12

8.41425 – 8.41475

162.0125 – 167.17

3260 – 3267

23.6 – 24.0

12.29 – 12.293

167.72 – 173.2

3332 – 3339

31.2 – 31.8

12.51975 – 12.52025

240 – 285

3345.8 – 3358

36.43 – 36.5

12.57675 – 12.57725

322 – 335.4

3600 – 4400

Above 38.6

13.36 – 13.41