Re: Wireless Networking Dep

[Donald Haes <HAES%MITVMA.bitnet@vmd.cso.uiuc.edu>]

We have a situation under study, with two different approaches. Indeed, the
device is excluded from MPEs under the low power device exclusion criteria
of IEEE/ANSI C95.1-1991: 7 (450/f) Watts, where "f" is the frequency in
MHz. In lieu of measurements, try the age old adage that "the pen is
mightier than the sword". Simple calculations of the device can be done,
making some assumptions. First, I assume the 1 mW is the EIRP, and that
the antenna is a dipole. Calculating the MPE from IEEE/ANSI C95.1-1991
Table 2 for uncontrolled areas we get:
MPE = (f/1500) = 902 MHz/1500 = 0.6 mW/cm^2 (using most restrictive carrier
frequency). Then, using the formula for a simple isotropic source:
S = PG/4piR^2 (where "S" is the equivalent free space power density, "P" is
the power, "G" is the gain [note: for EIRP, assume PG=1mW], and "R" is the
range. Solving for the range for S=MPE; R=[1mW/4pi(0.601mW/cm^2)]^-1/2,
R = =0.36 cm. Indeed, there is no exposure problem with these devices.