m080610 - deakin burwood wlan - emr survey report · the purpose of this rf measurement survey was...

of 14

EMC Technologies Pty Ltd ABN 82 057 105 549 176 Harrick Road KEILOR PARK VIC 3042 AUSTRALIA Telephone + 61 3 9365 1000 Facsimile + 61 3 9331 7455 Email [email protected] www.emctech.com.au

This document must not be copied or reproduced, except in full without the written permission of the Manager, EMC Technologies Pty Ltd

www.emctech.com.au *Comments and Recommendations are outside the scope of the NATA

accreditation

Radio Frequency Fields Survey conducted for

Deakin University on

Wireless Networking Equipment at

LB Building, Deakin University Burwood VIC 3125

Report Number: M080610

Issue Date: 14th August 2008

Report No. M080610 of 14



accreditation

Radio Frequency Fields Survey

conducted for Deakin University

Report Number: M080610

Test Location: LB Building Test Address: Deakin University, Burwood VIC 3125 Contact: Michael O’Donogue Phone: 03 9246 8175 Test Standards: ARPANSA Radiation Protection Standard

Radiation Protection Series No.3: Maximum exposure levels to Radiofrequency Fields, 3 kHz to 300 GHz. AS/NZS 2772.2: 1988 Radio frequency Radiation Part 2: Principles and methods of measurement- 300 kHz-100 GHz.

Test Dates: 4th June 2008 Client: Deakin University, Human Resources Services Address: Deakin University, Burwood VIC 3125 Phone: 03 9246 8175 Test Engineers:

Justin McLoughlan

James Zombolas Authorised Signature:

Stephen Phillips

Systems Manager EMC Technologies Pty Ltd




accreditation

Radio Frequency Fields Survey

Conducted for Deakin University

Report Number: M080610 1.0 INTRODUCTION

A Radio Frequency (RF) field measurement survey was performed at the LB Building, Deakin University, Burwood on the 4th of June 2008. Areas throughout levels 2 to 5 of the building were assessed. Electromagnetic emissions from wireless LAN equipment transmitting at approximately 2.4 GHz equipment were assessed. The measurement results are indicative only of the time that they were taken as the operating configuration of the antennas at the time of the measurements could not be confirmed. The measurements were performed during typical working hours. The purpose of this RF measurement survey was to determine the levels of RF fields in the areas where staff and students are required to access. The terms RF fields, Electromagnetic Radiation (EMR), Electromagnetic Fields (EMF) and Electromagnetic Energy (EME) have the same meaning when used in this report.

2.0 RF HUMAN EXPOSURE STANDARDS 2.1 ARPANSA RPS No. 3

The ARPANSA Radiation Protection Standard, Radiation Protection Series No.3: “Maximum exposure levels to Radiofrequency Fields, 3 kHz to 300 GHz”. This Standard specifies limits of human exposure to radiofrequency (RF) fields in the frequency range from 3 kHz to 300GHz.

2.2 ARPANSA RPS No. 3 Definitions

Occupational Exposure No occupationally exposed person, aware user or person in a controlled area, is to be exposed to RF fields that exceed the occupational exposure limits. An RF worker is a person who may be exposed to RF fields under controlled conditions, in the course of and intrinsic to the nature of their work. Such persons are subject to the requirements of Section 5.1 of the ARPANSA standard. This category excludes pregnant workers and personnel under the age of 18. General Public Exposure No General Public persons are to be exposed to RF fields in excess of the Non-Occupational limits. This definition excludes occupational exposure, exposure of aware users, and medical exposure. This category includes pregnant workers and personnel under the age of 18.




accreditation

2.3 Applicable Exposure Limits

The ARPANSA standard defines the limits of exposure in terms of power flux density, electric and magnetic fields for the relevant frequency. Compliance with the basic restrictions is presumed if the reference levels are not exceeded. The following table is an extract from Table 7 of the ARPANSA RPS3 standard shows the occupational and general public limits for the relevant frequency range. Table 1: ARPANSA RF Exposure Limits – Electric Field

Frequency Range General Public Exposure Equivalent Plane Wave Power Flux Density

2 GHz – 300 GHz 10 W/m2

3.0 MEASURMENT METHOD 3.1 Equipment

Narrowband Equipment

A spectrum analyzer and horn antenna were used to make the frequency selective measurements. A laptop computer was used to store the measurement data.

Equipment Manuf. Calibration

Due Date Calibrated

By Model

Number Serial

Number Spectrum Analyser HP Sept 2008 Agilent 8593EM 3412A00105

RF Cable Huber and Suhner July 2009 EMC 4272 C372

Horn Antenna EMCO Feb 2009 EMC 3115 8908-3282

Broadband Equipment

A Narda EMR-300 meter was used in conjunction with the following probes for the RF measurements. The model 8.3 E-field probe is sensitive to electric fields in the frequency range 100 kHz to 3 GHz. Table 3: Equipment List

Equipment Manuf. Calibration Due Date

Calibrated By

Model Number

Serial Number

E-Field Probe NARDA Sept 2008 NPL 8.3 BD-0039

EMR-300 NARDA Sept 2008 NPL EMR-300 N-0055




accreditation

3.2 Location of Measurements

Figure 1: Measurement Locations – Level 2





accreditation






accreditation

3.3 Measurement Procedure

Narrowband Measurements Narrowband measurements were taken at typical access heights i.e. measurement positions located in corridors were taken at head height of a standing person, measurements made inside rooms at staff desks were made at head height of a seated person. A horn antenna was used to make the measurements. The horn antenna was mounted in Vertical Polarisation, a measurement taken, and then rotated to Horizontal polarisation and another measurement taken. The electric field in the frequency range of the wireless LAN’s was measured using the Max Hold function of the spectrum analyser. The field was sampled in Max Hold until the full profile of the emission was recorded. The measurement data was stored using a laptop computer. A Bandwidth Correction Factor was applied to account for the emission bandwidth being wider than the resolution bandwidth of the spectrum analyser. The frequency selective narrowband measurements do not consider the duty cycle of the emission as the analyzer is in Max Hold mode until the full emission is profiled. Therefore the final results will represent the maximum possible exposure from the system. In practice, the actual exposure may often be many times below the presented result. Broadband Measurements Measurements were taken with the broadband probe at the positions labelled “BB” shown in Section 3.2. The probe was positioned 50cm from the transmitting antenna. The broadband probe level presented can be considered to be an actual exposure level because the response time of the probe produces a time averaged result. The levels presented in the Broadband section were valid at the time of measurement, but will vary depending on the actual loading of the system, e.g. number of users and information being transferred.

3.4 Measurement Uncertainty The following measurement uncertainty is typical for NATA accredited laboratories and has been conservatively determined in accordance with ISO17025 and NATA requirements.

Broadband Measurement Uncertainty: ±3.0 dB

Narrowband Measurement Uncertainty: ±3.0 dB




accreditation

4.0 MEASUREMENT RESULTS

Narrowband Results The results in Table 4 are the frequency specific Equivalent Plane Wave Power Density levels measured using a horn antenna and a spectrum analyser. Refer to Section 3.3 and Section 6 for measurement method discussion and section 3.2 for measurement locations. Table 4: Narrowband measurement results

Position Level Measured Equivalent Power Density

ARPANSA GP Limit

% of ARPANSA GP Limit

NB 1 3 0.006185 W/m2 10 W/m2 0.06185% NB 2 3 0.000079 W/m2 10 W/m2 0.00079% NB 3 3 0.000003 W/m2 10 W/m2 0.00003% NB 4 3 0.000021 W/m2 10 W/m2 0.00021% NB 5 3 0.039383 W/m2 10 W/m2 0.39383% NB 6 3 0.000002 W/m2 10 W/m2 0.00002% NB 7 4 0.003085 W/m2 10 W/m2 0.03085% NB 8 4 0.000004 W/m2 10 W/m2 0.00004% NB 9 4 0.000009 W/m2 10 W/m2 0.00009% NB 10 4 0.000496 W/m2 10 W/m2 0.00496% NB 11 5 0.000360 W/m2 10 W/m2 0.00360% NB 12 5 0.000010 W/m2 10 W/m2 0.00010% NB 13 5 0.000006 W/m2 10 W/m2 0.00006% NB 14 5 0.000007 W/m2 10 W/m2 0.00007% NB 15 2 0.000033 W/m2 10 W/m2 0.00033% NB 16 2 0.000006 W/m2 10 W/m2 0.00006%




accreditation

Broadband Results The Results presented in Table 5 are the Equivalent Plane Wave Power Density, calculated from the electric field measured with the broadband probe. Refer to Section 3.3 and Section 6 for measurement method discussion and section 3.2 for measurement locations. The probe was held approximately 50cm from the wireless routers. Table 5: Broadband measurement results

Position Level Measured Equivalent Power Density

ARPANSA GP Limit

% of ARPANSA GP Limit

BB 1 3 0.009177 W/m2 10 W/m2 0.09177% BB 2 3 0.003151 W/m2 10 W/m2 0.03151% BB 3 3 0.001453 W/m2 10 W/m2 0.01453% BB 4 3 0.009677 W/m2 10 W/m2 0.09677% BB 5 4 0.003447 W/m2 10 W/m2 0.03447% BB 6 4 0.007666 W/m2 10 W/m2 0.07666% BB 7 4 0.002197 W/m2 10 W/m2 0.02197% BB 8 5 0.001784 W/m2 10 W/m2 0.01784% BB 9 5 0.002869 W/m2 10 W/m2 0.02869%

BB 10 5 0.002706 W/m2 10 W/m2 0.02706% BB 11 5 N/A W/m2 10 W/m2 N/A BB 12 2 0.002054 W/m2 10 W/m2 0.02054% BB 13 2 N/A W/m2 10 W/m2 N/A BB 14 2 0.003820 W/m2 10 W/m2 0.03820% BB 15 2 0.005125 W/m2 10 W/m2 0.05125%

N/A = Not Accessible – measurement staff could not access the immediate vicinity of the antenna.




accreditation

5.0 CONCLUSION

A Radio Frequency (RF) field measurement survey was performed in the vicinity of wireless routers at the LB Building, Deakin University, Burwood on the 4th June 2008. The locations of measurements are shown in Section 3.2 of this report. The results obtained from the survey show that the RF electric field strength levels at the locations indicated in Section 3.2 of this report were found to be many times below the general public limit levels specified in the ARPANSA Radiation Protection Standard. See Table 4 and 5 for details. Narrowband The highest exposure level measured using the frequency selective spectrum analyser method was 0.039383 W/m2 (0.39% of ARPANSA General Public limit) measured at position NB5. Position NB5 was in the “café bar” LB3.102, this measurement was taken at standing height of a person and is relative close proximity to the wireless router, see photo 2.

Broadband The highest exposure level measured using the broadband probe method was 0.009677 W/m2 (0.09677% of ARPANSA General Public limit) measured at position BB4.

The measurement results are indicative only of the time that they were taken as the operating configuration of the antennas at the time of the measurements could not be confirmed. All the measurements were taken during a normal university day, during normal working hours.




accreditation

6.0 COMMENTS AND RECOMMENDATIONS

Note: Comments and recommendations are outside the scope of the NATA accreditation. The measurement results indicate a significant difference between the Narrowband and Broadband methodologies. The narrowband spectrum analyser technique enables the complete bandwidth of the emission to be measured using the max hold function of the analyser and a bandwidth correction. However this method does not consider the duty cycle of the emission so the presented narrowband results indicate maximum possible exposure and will not vary with traffic. Wireless LAN access points transmit for very short periods of time, and the actual exposure may be many times lower then the narrowband result presented in this report. The broadband measurement technique level presented can be considered to be an actual exposure level. The levels presented in the Broadband section were valid at the time of measurement, but will vary depending on the actual loading of the system, e.g. number of users and information being transferred. The measurements were taken throughout a typical working day. To conclude, all the measurements taken were below the ARPANSA General Public limits, the conservative narrowband measurements showed higher levels at positions NB5, NB1 and NB7, this is directly related to the close proximity to the transmitting routers.




accreditation

APPENDIX A – PHOTOS

Photo 1: Wireless LAN measurement – Narrowband position NB1




accreditation






accreditation

Photo 4: Wireless LAN measurement – Broadband position BB1

m080610 - deakin burwood wlan - emr survey report · the purpose of this rf measurement survey was...

Documents