Case Study: Measurements of Radio Frequency Exposure from Wi-Fi Devices (sf10387)

Annex E – Detailed Measurement Results

This annex provides the detailed results ofeach test case performed in this study. The maximum value represents themaximum instantaneous value measured during the measurement time period, andthe minimum value represents the minimum instantaneous value measured duringthe measurement time period. The average value represents the average value measuredduring the measurement time period.

1a) Ambient levels from 50 MHzto 6 GHz at each measurement location with the tri-axis antennapositioned at a height of 1.75 metres

^a See Figure 4 for measurement locations.

2a) Ambient levels from 50 MHzto 6 GHz at one measurement location with the tri-axis antenna positioned at aheight of 1.25 metres

Table E.3 and Table E.4 list the measuredpercentages of SC6 limits for each specific service operating in the frequencyband from 50 MHz to 6 GHz at location P11.

Note:Bold represents the Wi-Fi bands in Canada.

Note:Bold represents the Wi-Fi bands in Canada.

Figure E.1 and Figure E.2 represent thesignals in the ambient environment when all wireless devices werenon-operational in the boardroom at location P11. As shown in Figure E.1, theNarda SRM 3006 meter was able to capture licence-exempt devices, such as Wi-Fiaccess points in the 2.4 GHz band, which were located in the area. In addition,cellular services in the 800 and 1900 MHz bands were prevalent and captured onthe meter.

Description of Figure E1

Figure E.1 – Signals in the RF ambient environment for the 50 MHz to3 GHz frequency band

Description of Figure E2

Figure E.2 – Signals in the RF ambient environment for the 3 to 6GHz frequency band

3a) Ambient levels from 50 MHzto 6 GHz at one measurement location with the tri-axis antenna positioned at aheight of 1.25 metres for a sweep time of 6 minutes

4a) Ambient levels from 50 MHz to6 GHz at one measurement location with a nine-point matrix representing a cross-sectionof the human body

Spatial averaging of the nine-point matrix (% SC6 limits): 0.00277%

1b) RF exposure levels from 2.4 to 5.825 GHz at each preselectedmeasurement location with the tri-axis antenna positioned at a height of 1.75 metres

Table E.7 lists the measured percentages ofthe SC6 limits when both Wi-Fi APs were operational and all Wi-Fi-enableddevices were in downloading mode. The percentages of the SC6 limits weremeasured within the Wi-Fi bands from 2400 to 2483.5 MHz, 5150 to 5350 MHz, and5470 to 5825 MHz. "Other" represents the contribution from other servicesoperating in the frequency bands from 2483.5 to 5150 MHz and from 5350 to5470 MHz.

^a See Figure 4 for measurement locations.

2b) RF exposure levels from 2.4 to 5.825 GHz at each preselected measurement location with the tri-axis antenna positioned at a height of 1.25 metres

^a See Figure 4 for measurement locations.

3b) Spatial- and time-averaged RF exposure levels from 2.4 to5.825 GHz at the location with the highest levels found from 1b and 2b

Time and spatial averaging of the nine-point matrix (% SC6 limits):0.099360%

4b) RF exposure levels for eight laptops connected to AP2 inuploading mode at a preselected measurement location with the tri-axis antennapositioned at a height of 1.25 metres

5b) RF exposure levels for eight laptops connected to AP2 inuploading mode and 16 laptops in downloading mode at a preselected measurementlocation with the tri-axis antenna positioned at a height of 1.25 metres

6b) RF exposure levels for one laptop connected to AP2 inuploading mode at a preselected measurement location with the tri-axis antennapositioned at a height of 1.25 metres

7b) RF exposure levels for one laptop connected to AP2 indownloading mode at a preselected measurement location with the tri-axisantenna positioned at a height of 1.25 metres

8b) RF exposure levels from 5150 to 5350 MHz with thetri-axis antenna positioned at 20 cm from AP1

9b) RF exposure levels from 2400 to 2483.5 MHz with the tri-axisantenna positioned at 20 cm from AP2

References

(1) Industry Canada GL-01, Guidelines for the Measurement ofRadio Frequency Fields at Frequencies from 3 kHz to 300 GHz
http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01451.html

(2) Industry Canada GL-08, Guidelines for the Preparation ofRadio Frequency (RF) Exposure Compliance Reports for Radiocommunication andBroadcasting Antenna Systems
http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf09945.html

(3) Industry Canada RSS-102 Radio Frequency (RF) ExposureCompliance of Radiocommunication Apparatus (All Frequency Bands)
http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01904.html

(4) Industry Canada's RSS-210 Low-power Licence-exemptRadiocommunication Devices (All Frequency Bands): Category I Equipment
http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01320.html

(5) Health Canada, Limits of Human Exposure to RadiofrequencyElectromagnetic Energy in the Frequency Range from 3 kHz to 300 GHz - SafetyCode 6 (2009)
http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/radio_guide-lignes_direct-eng.php

(6) Health Canada, Technical Guide for the Interpretation andCompliance Assessment of Health Canada's Radiofrequency Exposure Guidelines
http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/radio_guide-lignes_direct-eng.php

Footnotes

1. ¹ "Limitsfor uncontrolled environments" and "limits for controlled environments" are the terms used in the current (2009) edition of SC6. The limits for uncontrolled environments typically apply to the general public. In previous versions of SC6, these limits were defined as the "general public limits."
2. ² See GL-01, Guidelines for the Measurement of Radio FrequencyFields at Frequencies from 3 kHz to 300 GHz (http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01451.html).
3. ⁴ See RSS-210, Licence-exempt Radio Apparatus (All FrequencyBands): Category I Equipment (http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01320.html).
4. ⁵ See RSS-102, Radio Frequency (RF) Exposure Compliance ofRadiocommunication Apparatus (All Frequency Bands) (http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01904.html).
5. 6 See Health Canada's Limits of Human Exposure toRadiofrequency Electromagnetic Energy in the Frequency Range from 3 kHz to 300GHz — Safety Code 6 (2009) (http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/radio_guide-lignes_direct-eng.php).
6. ⁷ RF exposure evaluation is the method used to evaluate the RF field strength levels generated by a device. RF exposure evaluation is required if the separationdistance between the user and the device is greater than 20 cm.
7. ⁸ Wi-Fi access points are commonly called "Wi-Fi routers."
8. ⁹ SAR evaluation is the method used to evaluate the SARlevels from a device by physical measurement or computational modeling techniques.SAR evaluation is required if the separation distancebetween the user or bystanders and the device is less than or equal to20 cm.
9. ¹⁰ A sweep is defined as the time required for one spectrum(frequency band, or bands, under investigation) to be measured and displayed.
10. ¹¹ Continuous transmission represents a duty cycle ofapproximately 100%.
11. ¹² Determination of the e.i.r.p. was based on radiated emissiontests performed in an anechoic chamber at 3 metres from the access points with theirconducted power set at 24 dBm.
12. ¹³ Wi-Fi transmitted signals during regular operation (i.e. not intest mode) are pulsed, with a low duty cycle.
13. ¹⁴ Available at http://www.netstumbler.com.
14. ¹⁵ Available at http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01451.html.
15. ¹⁷ At 20 cm, the tri-axis antenna was located in the near fieldbecause the antenna of AP1 is considered an electrically large antenna (D = 17cm). E and H field measurements would be required at 20 cm. However, H fieldmeasurements were not performed during this case study.
16. ¹⁸ The highest values for expanded measurement uncertainty, + 2.9 /-4.3 dB, were added to the measured RF exposure value.
17. ¹⁹ A distance of 20 cm represents the distance at which amanufacturer will generally demonstrate compliance with the RF exposurerequirements set forth in RSS-102.
18. ²⁰ AP2 was considered an electrically small antenna.
19. ²¹ AP1 was considered an electrically large antenna.