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Publication Number: 460108 Rule Parts: 15C Publication Date: 07/12/2018
Keyword: Antennas for radiated emission measurements below 30 MHz

First Category: Test Sites and Accreditations
Second Category: General [Test Sites and Accreditations]

Question:   May a monopole (rod) antenna be used for performing radiated emission measurements below 30 MHz?



Answer:  

The procedures for measuring radiated emissions for intentional and unintentional radiator devices are found in ANSI C63.10-2013 and ANSI C63.4-2014, respectively, including recommended types of measurement antennas. It is not acceptable to use an active or passive monopole (rod) antenna when performing measurements to demonstrate compliance with the FCC radiated emission limits below 30 MHz. Calibrated loop antennas generally provide more accurate and repeatable field strength measurement results below 30 MHz [FCC 03-149, Second Report and Order, docket no. 01-278, para. 40]. Per Section 15.31, the monopole antenna provisions in 4.5.3 and 8.2.2 of ANSI C63.4-2014 are excluded for FCC compliance testing purposes.

Unintentional Radiators: Subclause 4.5 of ANSI C63.4-2014 provides information on selecting the correct measurement antenna for radiated emission measurements. Footnote b to Table 2 of ANSI C63.4 explains the restriction on the use of the monopole (rod) antennas for compliance measurements below 30 MHz.

Intentional Radiators: Subclause 4.3.1 of ANSI C63.10-2013 provides information on selecting the correct measurement antenna for radiated emission measurements. Footnote b to Table 1 of ANSI C63.10 explains the restriction on the use of monopole (rod) antennas for compliance measurements below 30 MHz.

When performing radiated emission measurements below 30 MHz for compliance testing of Part 15 and Part 18 devices, use of either an active or passive loop antenna is required. Other information about test sites and antennas for radiated emission measurements below 30 MHz is given in KDB Publications 414788 and 629601.


 



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