On the Effectiveness of Aluminium Foil Helmets:
An Empirical Study
Ali Rahimi1, Ben Recht 2, Jason Taylor 2, Noah Vawter 2
17 Feb 2005
1: Electrical Engineering and Computer Science department, MIT.
2: Media Laboratory, MIT.
Among a fringe community of paranoids, aluminum helmets serve as the
protective measure of choice against invasive radio signals. We
investigate the efficacy of three aluminum helmet designs on a sample
group of four individuals. Using a $250,000 network analyser, we find
that although on average all
helmets attenuate invasive radio frequencies in either directions
(either emanating from an outside source, or emanating from the
cranium of the subject), certain frequencies are in fact greatly
amplified. These amplified frequencies coincide with radio bands
reserved for government use according to the Federal Communication
Commission (FCC). Statistical evidence suggests the use of helmets may
in fact enhance the government's invasive abilities. We speculate that
the government may in fact have started the helmet craze for this reason.
It has long been suspected that the government has been using
satellites to read and control the minds of certain citizens. The use
of aluminum helmets has been a common guerrilla tactic against the
government's invasive tactics . Surprisingly,
these helmets can in fact help the government spy on citizens by
amplifying certain key frequency ranges reserved for government
use. In addition, none of the three helmets we analyzed provided
significant attenuation to most frequency bands.
We describe our experimental setup, report our results, and conclude
with a few design guidelines for constructing more effective helmets.
The three helmet types tested
|The Classical||The Fez|
We evaluated the performance of three different helmet designs,
commonly referred to as the Classical, the Fez, and the Centurion.
These designs are portrayed in Figure 1. The helmets were made of
Reynolds aluminium foil. As per best practices, all three designs were
constructed with the double layering technique described elsewhere
A radio-frequency test signal sweeping the ranges from 10 Khz to 3 Ghz
was generated using an omnidirectional antenna attached to the Agilent
8714ET's signal generator.
The experimental apparatus, including a data recording
laptop, a $250,000 network analyser, and antennae.
A network analyser (Agilent 8714ET) and a directional antenna measured
and plotted the signals. See Figure 2.
Because of the cost of the equipment (about $250,000), and the limited
time for which we had access to these devices, the subjects and
experimenters performed a few dry runs before the actual experiment
(see Figure 3).
Test subjects during a dry run.
The receiver antenna was placed at various places on the cranium of 4
different subjects: the frontal, occipital and parietal lobes. Once
with the helmet off and once with the helmet on. The network analyzer
plotted the attenuation betwen the signals in these two settings at
different frequencies, from 10Khz to 3 Ghz. Figure 4 shows a typical
plot of the attenuation at different frequencies.
A typical attenuation trace form the network analyser
For all helmets, we noticed a 30 db amplification at 2.6 Ghz and a 20
db amplification at 1.2 Ghz, regardless of the position of the antenna
on the cranium. In addition, all helmets exhibited a marked 20 db
attenuation at around 1.5 Ghz, with no significant attenuation beyond
10 db anywhere else.
The helmets amplify frequency bands that coincide with those allocated
to the US government between 1.2 Ghz and 1.4 Ghz. According to the
FCC, These bands are supposedly reserved for ''radio location'' (ie,
GPS), and other communications with satellites (see, for example,
2.6 Ghz band coincides with mobile phone technology. Though not
affiliated by government, these bands are at the hands of
It requires no stretch of the imagination to conclude that the current
helmet craze is likely to have been propagated by the Government,
possibly with the involvement of the FCC. We hope this report will
encourage the paranoid community to develop improved helmet designs
to avoid falling prey to these shortcomings.
The authors would like to thank Andy (Xu) Sun of the MIT Media Lab for
helping with the equipment, Professor George Sergiadis for lending us
the antennae, and Professor Neil Gershenfeld for allowing us the use of
his lab equipment.