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Re: RF biological hazards? Change in ANSI standard.. (fwd)
---------- Forwarded message ----------
Date: Tue, 5 May 1998 08:20:12 -0700
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: RF biological hazards? Change in ANSI standard..
> ---------- Forwarded message ----------
> Date: Mon, 04 May 1998 18:58:21 -0700
> From: Jim Lux <jimlux-at-earthlink-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: RF biological hazards? (fwd)
>
In a prior post, I wrote:
> The ANSI standard (C95.1-1974) (for 10-300 MHz) is 200 V/meter and
> 0.5A/m (both RMS). In the far field 300 V/meter = 250 W/m^2 = 0.8 A/m.
This is now obsolete, and the newer ANSI standard is substantially lower. A
more recent standard (C95.1-1991) and other standards essentially try to
keep the absorbtion of RF energy to less than 0.4 Watts/kg. Of course, it
is a bit tricky to actually measure absorbption, so a guideline based on
power density has been formulated, which takes into account the shape and
size and dielectric properties of the "typical" human. The newer spec is
500 V/m (f< 3MHz) or 300 A/m (f<100 kHz). Above the threshold frequency,
the limit drops in inverse proportion to frequency to another plateau in a
maximum absorbtion area of 30-300 MHz (for E) or 100-300 MHz (for H) at
which the max power density is 1 mW/cm^2 = 0.3 A/m = 50 V/m.
The higher limit for magnetic fields at low frequencies presumably reflects
the fact that humans are basically non-magnetic and the absorption is quite
low.