1. INTRODUCTION RESULTS & CONCLUSION
OUTDOOR EXPOSURE TO RF- RADIATION OF WIFI FOR WIRELESS CITY APPLICATIONS G. Decat, G. Meynen, D. Wilczek and L. Deckx VITO - Integrated Environmental studies - Boeretang 200 – BE Mol – Belgium
The 23rd PIERS 2008 in Hangzhou China March 24-28, 2008 (in Grand Metropark Hotel, which is located in the city's commercial and financial center minutes walk to the famous West Lake,
INTRODUCTION
City services via the wireless interaction between wall fixed outdoor wifi access points (AP’s) and PDA’s become more and more popular in every city. In order to assess the magnitude and the possible risks of the RF-field generated by the AP’s when activated by the PDA, VITO measured the spatial distribution of the E-field in the city of Hasselt and evaluated the risk respective to the Belgian exposure standard (10 MHz – 10 GHz)(2005) from which the basic restriction SAR value is four times lower than the 0.08 W/kg of ICNIRP(1998).
METHOD
The E-field of 28 AP’s (fig.1) was measured in 28 different streets by means of the Fieldcop and Narda SRM 3000 spectrometers. Figure 2 shows the spectrum in which the field was measured whereas figures 3 and 4 show that measurements were performed in a vertical (0.1, 1, 1.75 m) and a 3 directional horizontal plane. The AP’s were activated by watching the video streaming on the PDA while it was placed below the AP (fig. 3) and behind the spectrometer (fig. 4) respectively. In each point the rms of the E-field was averaged over 6 min..
RESULTS & CONCLUSION
The table below shows the maximum E-field measured at a height of 1.75 m (PBS) and the sample (n = 28) median of the 6’ averaged rms E-field obtained at a height of 1 m in the 3 horizontal directions for the 2 activation conditions.
The conclusion is that all 6’ averaged rms values and even the maximum E-veld of the 3528 sample values are far below the reference level (30.7 V/m) of the Belgian standard and within the interpretation of this standard no health risks are to be expected by the outdoor wifi-applications
Figure 2
Figure 3: PBA-condition
Figure 4: PBS-condition
MHz
Figure 1
MAXIMUM
E-FIELD (mV/m) AT 1.75 cm HEIGH (PBS)
DISTANCE
FROM AP
MEDIAN OF 6’ AVERAGED RMS E-FIELD (mV/m)
Direction 1
Direction 2
Direction 3
PBA
PBS
2132 -
441
1483 1
368
460
300
313
239
332
792 2
268
362
160
151
376
487 4
154
312
109
237
114
316
392 8
119
274 80
247
257 16 89
259 58
255 63
291 32
250 53
216 52
279