Peruse a certain kind of website these days and you’ll
find warnings about the lethality of RF transmissions in the
frequency ranges slated for 5G networks. One site quotes
Devra Davis, director of the Board on Environmental Studies
and Toxicology of the U.S. National Research Council,
who warns that our sweat glands act as antennas for 5G
wavelengths and 5G wavelengths have never been tested
for health effects. Another points to an IEEE paper by Om
Gandhi, chair of the EE Dept. at the University of Utah, who
found that a large number of cell phones can emit 11x the
US FCC radiation limit and three times the European/ICNIRP
limits. Yet another webpage shrieks that 5G uses nearly the
same frequency as weaponized crowd control systems (96 GHz).Of course, it’s easy to find fringe websites warning about
all sorts of health issues, and it appears that health issues
concerning 5G are no exception. But some of the claims these
sites make has questionable scientific underpinnings. For
example, when sciencebasedmedicine.org examined claims
about harm from cell phone radiation, it found that virtually
none of the harmful “effects” had been reproduced in follow
up studies. It also found evidence that proponents of theories
about harmful cell phone radiation misstate the findings of
key studies that have found cell phones cause no harm.
That brings us to Gandhi’s IEEE paper. His group
examined SAR (specific absorption rate) test data for 450
cell phones that were held in contact with the human
body. SAR tests quantify the magnitude and distribution of
electromagnetic energy that biological objects absorb when
exposed to RF fields. Gandhi thinks these close-contact tests
approximate the way most people use cell phones though
manufacturers now recommend phones be held 5, 10, or 15
up to 25 millimeters (about an inch) from the body.
Gandhi has a point. I can’t ever recall being told when
purchasing a cell phone that I should keep it an inch away
from my skin.
One thing is clear: SAR tests are likely to become
increasingly important and potentially controversial as 5G
gear proliferates. So it’s useful to take a closer look at the tests
themselves. For that, we spoke with Bryan Taylor and Nicholas
Abbondante, both engineers at Intertek Group plc, an
independent test lab that, among other things, runs SAR tests.The tests use a “phantom” filled with a liquid that simulates
the electrical qualities of the human head or body. Hall-effect
magnetic probes measure SAR in watts-per-kilogram of tissue.
The Intertek engineers say the FCC SAR levels can
be tough to meet. They estimate that only about half the
equipment they test passes the first time. When there’s a
problem, it is usually because a portion of the device other
than the antenna radiates energy.
Additionally, manufacturers that have been through SAR
testing develop a bag of tricks to help mitigate difficulties, the
engineers say. One example: Designing the chassis to keep
the RF transmitter farther away from the human user.
The Intertek engineers also point out that manufacturers
increasingly design-in proximity sensors to detect when the
RF antenna is too close to a human. Tablets, for example,
generally employ these sensors to either reduce the RF output
from specific antennas or switch it off completely when a user
puts the tablet on their lap.
The jury is still out on what levels of 5G RF energy can
be considered safe for humans and at what distances. But
you can probably expect to see a lot more measures aimed at
squelching RF output when humans are close by.Will 5G be lethal?
(^2) DESIGN WORLD — EE NETWORK 6 • 2019
TEST & MEASUREMENT HANDBOOK
LELAND TESCHLER
EXECUTIVE EDITOR
Lee Editorial — Test and Measurement HB 06-19.indd 2 6/7/19 11:26 AM