Published: TV Technology Magazine

Issue:  December 4, 1997





FCC Issues New RFR Compliance Regulations       

by Joe Fedele



***************************************************************************************************************        



THE FOLLOWING IS A SIDEBAR THAT RAN IN THE SAME ISSUE AS THE STORY LISTED ABOVE



****************************************************************************************************************



Understanding OET-65                                                    



        When the FCC’s Office of Engineering and Technology (OET) issued "OET-65, Evaluating 

Compliance for Human Exposure to Radio Frequency Electromagnetic Fields," it represented a 

revision of its original RF radiation guidelines, also known as Edition 97-01. These first guidelines 

for evaluating human exposure to emissions were issued back in 1985 and were based on studies 

performed in 1982 by the American National Standards Institute (ANSI).

 

        Edition 97-01 includes two attachments, Supplements A and  B. Information specifying 

compliance for radio and television broadcast stations is included in Supplement A while 

Supplement B provides guidelines for Amateur Radio Services.

        The stated purpose of  OET-65 is "to provide assistance in determining whether proposed or 

existing transmission facilities, operations or devices comply with limits for human exposure to 

RFR" as defined in the rules adopted by the FCC.

        The bulletin offers guidelines and suggestions for evaluating compliance but was not 

intended to establish a mandatory procedure or methods for performing such measurements.

        The latest guidelines incorporate limits for Maximum Permissible Exposure (MPE) in terms of 

electric and magnetic field strength and power density for transmitters operating at frequencies 

between 300 kHz and 100 GHz.  Limits encompassing localized or "partial body" absorption were 

used primarily for evaluating exposure due to miniature transmission devices such as hand-held 

portable telephones.  The implementation of the newer guidelines for mobile and portable devices 

became effective August 7, 1996. 

        The FCC's limits are derived from exposure criteria quantified in terms of specific absorption 

rate (SAR). SAR is a measure of the rate of energy absorption by the body as specified for both 

whole-body exposure and partial-body or localized exposure.  The basis for these limits is a 

whole-body averaged SAR threshold level of 4 watts per kilogram (Wpkg).  The SAR threshold is 

then averaged over an entire body mass and is presumed to be indicative of what has been 

determined to be a potentially hazardous exposures level.  

        These guidelines also define a two-tiered approach to determining excessive exposure limits, 

based on Occupational and General Population situations.  Occupational levels are less stringent 

in terms of allowable RFR exposure because they assume that workers in high RFR 

environments are aware of the dangers imposed by radiating elements and will take appropriate 

actions to limit exposure.  The transient nature of workers in such an environment is also taken 

into consideration.

        General Population standards, on the other hand, assume that the public at large--in an 

uncontrolled RFR environment--may not be fully aware of the potential for exposure and cannot 

exercise control over it.

        OET-65 includes discussions and calculations for both Near-Field and Far-Field radiation 

and how they are each treated under these guidelines. 

        

A copy of OET-65 Edition 97-01 may be obtained at the FCC's OET 

Website: http://www.fcc.gov/oet/info/documents/bulletins