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18133localized specific absorption rate (SAR)limits; and (3) for all other transmitters,based on a set of formulas for maximumpermissible exposure (MPE) limits. Thenew exemption criteria apply to all ofthe Commission’s rules authorizing RFsources. Under the new rules, everyapplicant for equipment authorizationand every licensee prior to deploymentor commencement of operations maydetermine whether the device ortransmitter falls under one of the classesof exemptions. If the device ortransmitter falls under one of theseclasses of exemption, no additionalaction is necessary. If not, the applicantor licensee will have to perform aroutine evaluation to determinecompliance with the existing RFexposure limits. The Commissionreasoned that this new process wouldnot impose any significant burdens onimpacted parties since the underlyingexposure rules and parties’ obligationsunder the rules remain the same; thenew rules only modify the process usedto demonstrate compliance.4. In response to comments that therule changes are unnecessary and willbe burdensome and some parties maylose their service-based exemptions, theCommission noted that unlike in thepast, fixed RF communicationsequipment is now located on rooftopsthat are accessible to the public and onother structures near ground level thatare not spatially removed from publiclyaccessible areas at similar heights. Toachieve consistently reliable compliancewith the existing RF exposure limits, theCommission decided that these sorts ofinstallations warrant an affirmativedetermination of compliance with theRF exposure requirements.1. Exemption Criteria—Single RFSource.5. A single RF source will be exemptfrom RF exposure evaluation under anyone of three circumstances: (1) The RFsource transmits at no more than 1 mWtime-averaged available (matchedconducted) power; (2) the RF source isnormally separated between 0.5 and 40cm from the human body, in thefrequency range between 300 MHz and6 GHz, and transmits at no more thanthe average power threshold result fromthe formula the Commission adoptedbased on the localized SAR limits; or,(3) for all other fixed, mobile, andportable transmitters, the RF sourcetransmits at no more than the averagepower threshold result from the set offormulas the Commission adopted basedon the MPE limits at separationdistances from any part of the radiatingstructure of at least l/2p (RF signal freespace wavelength divided by 2p) in allservice categories.6. 1-mW Blanket Exemption. Forextremely low-power fixed, mobile, andportable RF sources, the Commissionadopted a blanket RF exposureevaluation exemption for a singletransmitter operating with up to 1 mWof time-averaged available (matchedconducted) power, irrespective of theseparation distance from the humanbody. The 1-mW exemption isindependent of service type and coversthe full frequency range from 100 kHzto 100 GHz, but it may not be used inconjunction with other exemptioncriteria, or in devices with higher-powertransmitters operating in the same timeaveraging period. The 1-mW blanketexemption applies for any separationdistance, including distances of lessthan 0.5 cm and where there is noseparation, e.g., medical implantdevices.7. SAR-Based Exemption. For fixed,mobile, and portable RF sources near ahuman body, where the separationdistance is normally between 0.5 and 40cm and may be less than l/2p, theCommission adopted the new RFexposure evaluation exemption formulashown here for time-averaged powerthresholds (specified in mW) forexemption of single portable, mobile,and fixed RF sources at 0.3–6 GHz. Asource is exempt if each of themaximum time-averaged available(matched conducted) power andeffective radiated power (ERP) is nomore than:8. The formula provides, as a functionof separation distance and frequency, athreshold power below which a singleRF source is exempt from further RFexposure evaluation. It applies to fixed,mobile, and portable RF sources in anyservice at a separation distance between0.5 cm and 40 cm from the body, andis applicable in the frequency rangefrom 300 MHz through 6 GHz. The SARbased thresholds are derived based onthe frequency, power, and separationVerDate Sep 11 201416:27 Mar 31, 2020Jkt 250001PO 00000Frm 00029Fmt 4700Sfmt 4700E:\FR\FM\01APR1.SGM01APR1ER01AP20.001 /GPH jbell on DSKJLSW7X2PROD with RULESFederal Register / Vol. 85, No. 63 / Wednesday, April 1, 2020 / Rules and Regulations

jbell on DSKJLSW7X2PROD with RULES18134Federal Register / Vol. 85, No. 63 / Wednesday, April 1, 2020 / Rules and Regulationsdistance of the RF source. The formuladefines the thresholds in general foreither available maximum timeaveraged power or maximum timeaveraged ERP, whichever is greater.9. If the ERP of a device is not easilydetermined, such as for a portabledevice with a small form factor,available maximum time-averagedpower (i.e., maximum power deliveredinto a matched antenna, consideringline loss or any other loss thatdiminishes the power delivered to anantenna) may be used exclusively if thedevice antenna or radiating structuredoes not exceed an electrical length ofl/4. A coherent phased array of antennaelements is to be treated as a singleantenna or RF source with separationdistance determined from the nearestantenna element.10. For devices with antennas oflength greater than l/4 where the gainis not well-defined but always less thanthat of a half-wave dipole, the availablemaximum time-averaged powergenerated by the device may be used inplace of the maximum time-averagedERP, in situations where that ERP valueis not known. This would apply, forinstance, to ‘‘leaky’’ coaxial distributionsystems, RF heating equipment, andother typically unintentionally radiatingor Industrial, Scientific and Medical(ISM) devices. The SAR-basedexemption threshold, Pth, is defined interms of maximum time-averaged powerand in accordance with the sourcebased time-averaging requirementsdescribed in § 2.1093(d)(5) of the rules.Time-averaged power measurements arenecessary to determine if the maximumoutput of a transmitting antenna (ERP)or matched conducted transmitterpower is above the proposed thresholdfor exemption from routine SARevaluation. The Commission’s Office ofEngineering and Technology (OET) willpublish in its Knowledge Database(KDB) the power measurement and SARtest procedures necessary todemonstrate compliance with the RFexposure limits.11. While commenters supported thebasic idea of a uniform formula for anSAR exemption, several commentersdisagreed with the proposed formula,contending it was overly conservativeand inconsistent with the operation ofcurrent devices. Instead, partiessupported use of the InternationalElectrotechnical Commission’s (IEC’s)standard IEC 62479 (2010), whichprovides alternative recommendationsfor exemption of low-power devicesbased on SAR. For several reasons, theCommission was not persuaded that theIEC standard was appropriate. Eventhough the IEC’s standard uses dipolesVerDate Sep 11 201416:27 Mar 31, 2020Jkt 250001and flat phantoms as a starting point formodeling, and is applicable to the samefrequency range as the SAR exemptionformula (300 MHz–6 GHz), theCommission determined that the IECstandard departs significantly regardingthe applicable range of separationdistances and use of bandwidth, with anincreased complexity in the resultingformulas. In addition, the IEC modeldoes not directly incorporate antennadirectivity and states that it may notapply to devices with highly directiveantennas. To maintain simplicity, theCommission limited the exemptions tothose based solely on the relationship ofpower (both available or matched powerand ERP), separation distance, andfrequency, without other inputs—suchas antenna pattern or bandwidth—thatwould effectively render an exemptiondetermination as complex as anevaluation. It concluded that additionalcomplexity in the exemptions fromadditional inputs would result inregulations that were of little or nopractical utility as a simple exemptionprotocol; additional factors could beconsidered as needed or appropriate ina more thorough evaluation todemonstrate compliance. TheCommission also declined to extend theSAR-based exemption formula from 0.5cm to 0 cm because there is no modelingdata that validates such an extension.12. MPE-Based Exemption. Tosupport an exemption from furtherevaluation for frequencies from 300 kHzthrough 100 GHz, the Commission alsoadopted general frequency andseparation-distance dependent MPEbased ERP thresholds as shown belowin Table 2. The values in Table 2 applyto any single RF source (i.e., fixed,mobile, and portable transmitters) andspecify power and separation distancecriteria for each of the five frequencyranges used for the MPE limits.TABLE 2—SINGLE RF SOURCES SUBJECT TO ROUTINE ENVIRONMENTALEVALUATION UNDER old ERP(watts)0.3–1.34 .1.34–30 .30–300 .300–1,500 .1,500–100,0001,920 R23,450 R2/f23.83 R20.0128 R2f19.2 R2Note: R is in meters and f is in MHz.13. An RF source with ERP equal toor less than the Threshold ERP specifiedin Table 2 for the source frequencywould be considered exempt fromPO 00000Frm 00030Fmt 4700Sfmt 4700evaluation. In cases where ERP is notwell defined, the available maximumtime-averaged power may be used if thedevice antenna(s) or radiatingstructure(s) does not exceed anelectrical length of l/4. The separationdistance R is the smallest distance fromany part of the antenna or radiatingstructure to all persons, including thoseoccupationally exposed, duringoperation at the applicable ERP. In thecase of mobile or portable devices, theseparation distance R is from the outerhousing of the device where it is closestto the antenna. At sites with multiplefixed transmitters, or multiple mobile orportable transmitters within the samedevice, the formulas would be appliedin conjunction with the summationsdiscussed in the section below on RFExposure Evaluation ExemptionCriteria—Multiple RF Sources.14. The criteria shown in Table 2apply at separation distances from anypart of the radiating structure of at leastl/2p; if R is less than l/2p and otherexemptions do not apply, evaluation isrequired. Since l/2p is greater than 20cm at frequencies below 239 MHz, theseexemption criteria do not apply toportable devices that are operated bothat less than 20 cm from the human bodyand at frequencies below 239 MHz. Ingeneral, less restrictive SAR-basedexemption criteria may be used inaccordance with the formulas specifiedin Table 2, but these SAR-basedexemptions are not valid below 300MHz. Thus, there are no exemptioncriteria below 239 MHz for portabledevices (or for any antenna at less than20 cm), other than the 1 mW blanketexemption.15. The Commission declined toadopt commenters’ suggestions to adjustthe formulas to more readily exempttransmitters mounted on dedicated,access-controlled wireless supportstructures in the frequency range 300MHz to 3 GHz because simply beingbuilding-mounted does not precludepersons from having access to the areanear an antenna, particularly whenmounted low to the ground or in otheraccessible locations. The actual distancefrom potential human presence shouldbe taken into consideration. TheCommission rejected a commenter’sproposal to relax the standard fortransmitters located on structures whereaccess can be more readily controlledsince spaces adjacent to such a structuremay be readily accessible, rendering thetransmitter appropriate for anevaluation. It also rejected acommenter’s proposal to add a modifiedexemption formula that would applybetween 400 MHz and 3 GHz because itfound that the formula was based onE:\FR\FM\01APR1.SGM01APR1

18135inappropriate assumptions and couldnot ensure compliance with theCommission’s RF exposure limits.16. 1-mW Exemption. For multiplesources inside a single device, each ofwhich is capable of no more than 1-mW,the Commission adopted a minimum 2cm separation distance betweenantennas that operate in the same timeaveraging period, as proposed in the2013 RF Further Notice. In other words,if there are two or more RF sourcesinside a single device operating at thesame time and the nearest parts of theantenna structures are separated by lessthan 2 cm, the 1-mW exemption will notapply. However, if the sum of multiplesources is less than 1 mW during thetime-averaging period, they may betreated as a single source (separation isnot required), and exemptedaccordingly. As with the exemption fora single RF source, this exemptioncannot be used in conjunction withother exemption criteria, and medicalimplant devices may use only this 1mW exemption.17. Use of Summation Formulas. Insituations where RF exposure isgenerated from multiple sources at thesame time, all such sources areconsidered in aggregate to determinecompliance with the exposure limits.The Commission decided that the SARand MPE-based exemptions from RFexposure evaluation may be used alongwith known existing exposure levels toexempt multiple RF sources. This isaccomplished by normalizing eachsource power level to each matchingexemption threshold power anddetermining whether the total of all thenormalized powers is no more than 1.(Normalization here means dividing anRF source power level by thecorresponding exemption thresholdpower.) In addition, if pre-existingexposure levels are known, they mayalso be normalized to the exposurelimits to determine the remainingmargin available for exemption ofadditional sources to demonstratecompliance with the limit. Theseconcepts are applied to the antennas ofmultiple transmitters in a single deviceand to multiple fixed transmitters, asexplained below.18. Multiple RF Sources with FixedPhysical Relationship. To address thepotential exposure from multiplesimultaneously operating RF sourceswith a fixed physical relationship, theCommission adopted the summationformula shown below for all RF sources,regardless of whether portable, mobile,or fixed, rather than its proposals in the2013 RF Further Notice, which provideddifferent formulas for portable, mobile,and fixed transmitters. For sites ordevices with multiple transmitters, thesummation formula shown below willdetermine whether multipletransmitters using the single transmitterformulas are collectively exempt fromevaluation. This formula includes threesummation terms, the first two of whichare summations for the exemptions, thethird is to account for exposure fromexisting evaluations, which is describedin more detail below.Where:a equals the number of fixed, mobile, orportable RF sources claiming exemptionusing the Table 1 formula for Pth,including existing exempt transmittersand those being added.b equals the number of fixed, mobile, orportable RF sources claiming exemptionusing the applicable Table 2 formula forThreshold ERP, including existingexempt transmitters and those beingadded.c equals the number of existing fixed, mobile,or portable RF sources with knownevaluation for the specified minimumdistance.Pi equals the available maximum timeaveraged power or the ERP, whichever isgreater, for a fixed, mobile, or portableRF source i at a distance between 0.5 cmand 40 cm (inclusive).Pth,i equals the exemption threshold power(Pth) according to the Table 1 formula fora fixed, mobile, or portable RF source i.ERPj equals the available maximum timeaveraged power or the ERP, whichever isgreater, of a fixed, mobile, or portable RFsource j.ERPth,j equals the exemption threshold ERPfor a fixed, mobile, or portable RF sourcej, at a distance of at least l/2p, accordingto the applicable Table 2 formula at thelocation in question.Evaluatedk equals the maximum reportedSAR or MPE of fixed, mobile, or portableRF source k either in the device or at thetransmitter site from an existingevaluation.Exposure Limitk equals either the generalpopulation/uncontrolled maximumpermissible exposure (MPE) limit orspecific absorption rate (SAR) limit foreach fixed, mobile, or portable source, asapplicable.reduces the allowable margin remainingfor exemption at the location of interest(e.g., 20 cm for mobile RF sources). Alltransmitters must be considered, and alltransmitters that can operate at the sametime must be included in thesummation of multiple transmitters. If atransmitter is subsequently proposed tobe added under the Commission’spermissive change authorizationprocedures for portable or mobiledevices, a new calculation must bemade including the additionaltransmitter.20. In response to a commenter’ssuggestion that the Commissionincorporate further technical definitionsin its rules for terms used in thesummation formula beyond thoseproposed in the 2013 RF Further Notice,the Commission added definitions of‘‘available maximum time-averagedpower,’’ ‘‘effective radiated power(ERP),’’ and ‘‘time-averaging period’’ toits rules. However, because theCommission’s exemptions do not relyon delivered power but available power,it declined to adopt a definition for‘‘delivered maximum time-averagedpower.’’ The Commission clarified thatthe delivered maximum time-averagedpower would be the largest net powerdelivered or supplied to an antenna, asaveraged over a time period not toVerDate Sep 11 201417:01 Mar 31, 2020Jkt 25000119. The normalized contributions tothe total exemption threshold can bedetermined by calculating for each RFsource, whether mobile, portable, orfixed, the ratio of the maximum timeaveraged power (matched conductedpower or ERP, as appropriate) for thetransmitter, comparing it to theappropriate frequency- and distancedependent threshold, using the formulaabove for either time-averaged powerthresholds (mW) for exemption of singleportable, mobile and fixed RF sources,or Table 2, and summing those ratios. Ifthe ratios for all transmitters in a deviceoperating in the same time-averagingperiod are included in the total sum andthis sum is no more than 1 (i.e., 100percent), the cumulative contributionsdo not exceed the permissible limit anda location at a site or the device (i.e., alltransmitters within the device) areexempt from routine evaluation. Thebasic exemption criteria are containedin the P and ERP summation terms,while the Evaluated/Exposure Limitsum accounts for the preexistingexposure levels and correspondinglyPO 00000Frm 00031Fmt 4700Sfmt 4700E:\FR\FM\01APR1.SGM01APR1ER01AP20.002 /GPH

Office of Engineering and Technology at (202) 418-2470. SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Second Report and Order, Memorandum Opinion and Order, and Termination of Notice of Inquiry, ET Docket No. 03- 137, ET Docket No. 13-84, FCC 19-126, adopted November 27, 2019 and released December 4, 2019. The full text