Presentation on theme: "Washington Laboratories (301) 417-0220 web: www.wll.com7560 Lindbergh Dr. Gaithersburg, MD 20879 RF Exposure and Modular Equipment Considerations."— Presentation transcript:
Washington Laboratories (301) web: Lindbergh Dr. Gaithersburg, MD RF Exposure and Modular Equipment Considerations
RF Exposure Rules SAR and MPE Estimation Summary Based on current interpretations of US radio law by FCC Based upon the TCB Exclusion List and various interpretations by FCC Based upon experience of ATCB
RF Exposure: SAR or MPE ? Questions to ask: oIs device used at less than 20cm to the body? And is the device above the Low Threshold conditions in the TCB exclusion list of July 17, 2002? oIs the device listed in (c)? If the answer to either of the above is YES than SAR evaluation is required
Definitions and Nomenclature oHost-independent: certification for device to be installed and expected to comply in any applicable host – unfeasible for portable exposure conditions oModule: Transmitter operating (usually) internally as part of another device or product oFull Modular Approval: Part 15 Tx module that meets eight criteria of DA , e.g., EMC tested stand-alone (stand-alone SAR is undefined), FCC ID label on host, etc. A full Modular approval with unlimited SAR configurations is not allowed.
Definitions and Nomenclature oLimited Modular Approval (LMA): LMA is used with SAR testing on an Unlicensed module to allow SAR tests to be applied to more than one model. oLicensed module: Certification for Licensed Tx daughter-board or Tx box, installed in RF category Mobile or Fixed conditions only. Antenna might be specified with limit on gain. oDedicated host: Tx intended for OEM integration or permanent installation into a specific host product; also covered by 3-host method for integral-antenna plug-in cards. Applies specifically to Part 15 modules above 100mW
Portable Devices oOperate less then 20cm from any user or bystander oUsually involves body worn or ear or face held devices oSAR Testing required if above the low threshold limit in July 17, 2002 TCB Exclusion List oSome devices are specifically required by law to have SAR testing as a condition of Certification, regardless of RF Pout. oExample: Cellphones; a PCMCIA card
Safety Rule References on Human Exposure oANSI C95.1 oIEEE 1528 oOET 65 oOET 65-C oFCC Part oFCC Part Mobile Devices oFCC Part Portable Devices oFCC Part (b)(4) oFCC Part 15E
Part 15 and RF Exposure The FCC will require a MPE study (RF estimation) for both Mobile and Fixed devices. (i.e and UNII devices). Estimation should be performed with highest gain antenna of each antenna type. For SAR and MPE evaluation, the default limits are the Uncontrolled Environment. It is assumed that users of Part 15 devices have no understanding of radio principals. You cannot evaluate any Part 15 device to the Controlled/Occupational limits.
Part 15 and RF Exposure The vast majority of Low Power Part 15 Intentional Radiators are categorically excluded from Routine Evaluation under the FCC rules. However, the FCC will require a SAR test for RF category Portable devices if the power exceeds 60/f(GHz) if contact with antenna is allowed, or 120mW/f(GHz) if 2.5cm is maintained to the antenna. Example: key fob Tx do not need SAR test
Supplement C: MPE Exposure Limits
Supplement C: SAR Limits
MPE Estimation Formula To Determine Power Density (s): oS=P x G /4piR 2 oFCC requires that RF category Mobile devices calculate power density for 20cm. oCalculation of power density at other distances for Mobile products not allowed. oCalculation of power density for Fixed devices is allowed, as long as distance not shown less than 20cm
Full Modular Approvals (Part 15) By Definition, these transmitters must have own reference oscillator. In addition a separate letter on Applicant letterhead addressing all these items must accompany the filing: 1.RF shielding. 2.Buffered data input/output ports 3.Power supply regulation 4.Permanent antenna or unique connector 5.Tested in stand alone condition 6.Labeled with own ID number 7.Instructions to operator / OEM integrator 8.Must meet RF Exposure requirements.
Limited Modular Approval (LMA) Part 15 If any of the 8 elements on the preceding slide cannot be met, a limited modular approval may be obtained in some circumstances. LMAs define special circumstances where Certification is valid Example 1: Wireless mini-PCI b/g card without voltage regulation Example 2: Wireless mini-PCI b/g card with SAR results which may apply to a specific chassis or model notebook PC host.
Licensed Modules There is officially no such thing as a Licensed Modular Transmitter The Rules of DA do not apply – DO NOT ATTEMPT
Complex Example Notebook PC with built-in Bluetooth, WiFi, and GPRS oAre Part 15 transmitters separately Certified? oAre Part 15 transmitters Modular Approved? oAre any transmitters capable of co-location? oIs BT below 5mw? oAre any transmitters end-user installable? oLabeling?
SAR Testing Updates. oSAR Probes must be calibrated on a yearly basis. The only allowed exception is when the probe manufacturer specifically permits different calibration intervals. oTolerance between RF conducted power measured at the EMC lab and SAR lab must be within 5%. Common spectrum analyzers are good to only 1dB (~25%) oTCBs now allowed to do SAR approval work from 300MHz to 6GHz.
Additional Documents FCC has released specific guidance for SAR testing of WiFi products. FCC is now specifying specific combinations of channel, power, and data rates. FCC has released SAR review to TCBs to frequencies of 6GHz.
Contact Information William H. Graff President and Director of Engineering AmericanTCB, Inc Whittier Ave. McLean, VA mailto: Corporate Phone: (703) Corporate FAX: (703) Direct Mobile: SKYPE: whgraff