U.S. investigators increasingly confident directed-energy attacks behind Havana Syndrome

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35. Energy can be measured.

Additional Comments on Directed Radio Frequency Energy

In order to create the Frey effect of hearing and sensation of pressure within the head, there
are four distinct steps involving the energy conversion from radio frequency (RF) to acoustic
modalities. First, the RF energy penetrates the skull and couples to the neural tissue as a function of
impedance matching and absorption in the tissue, with penetrations of 2-4 cm for frequencies of
915 MHz to 2.45 GHz (Brace, 2010). This coupling, in turn, creates a rapid oscillation of
temperature changes that leads to a rapid, volumetric thermal expansion and contraction of local
tissues (i.e., the increase in thermal energy causes an increase in kinetic energy of atoms, pushing
against neighboring atoms to create an expansion or swelling in all directions). The oscillating
tissue expansion and contraction launches a thermoelastic pressure wave (Lin and Wang, 2007;
Yitzhak et al., 2009). If operated at the right pulse repetition frequency, the thermoelastic pressure
wave can propagate to and excite the cochlea and vestibular organs at the resonance frequency of
the cranium (Lenhardt, 2003; Yitzhak et al., 2014). Intracranial focusing is possible depending on
the incident angle of the incoming RF radiation. Localization and intensity effects within a room
can be achieved through nonlinear beat wave effects with careful design of the RF source and
antenna. The absence, however, of electromagnetic disruption of other electronics within the
immediate home/office environment suggests an upper bound to the RF energy, with implications
for a potential RF system design. The average power densities associated with some of these
effects (e.g., Frey effect hearing) are so low that they would not disrupt nearby electronics in a
fashion similar to high-power microwaves (HPM) (Hoad, 2007; Jinshi et al., 2008). The lack of
perceptual heating would also rule out other non-lethal HPM systems that have been developed for
crowd control (e.g., Department of Defense’s 95GHz Active Denial System that only penetrates the
skin to 1/64 an inch but heats the skin to uncomfortable levels within seconds) (D’Andrea et al.,
2008; DoD, 2020; Nelson et al., 2000).

It is well-known that the vestibular end organs and regions of the brain involved in
processing of space and motion information may be excited by energy sources other than rotational
or linear accelerations. External sonic, galvanic, and magnetic stimuli are used for diagnostic,
experimental, and therapeutic purposes in neuro-otology and vestibular research such as generating
vestibular evoked myogenic potentials (sonic), investigating vestibular response thresholds
(galvanic), and as emerging therapies for chronic dizziness (transcranial magnetic and electrical
stimulation) (Cha et al., 2013). Clinical observations also suggest that certain patients with
vestibular disorders (e.g., Ménière’s disease) may be susceptible to exacerbations of their
symptoms in response to rapid changes in atmospheric pressure as occur with quickly moving
weather fronts or changes in elevation during air or land travel (Gürkov et al., 2016). However, the
potential for RF sources to stimulate the vestibular end organs via thermoelastic pressure waves or
to excite central nervous system pathways via transduction akin to the Frey effect are not known. If
these effects exist, then a few observations may be made about their potential manifestations. A
thermoelastic pressure wave would be omnidirectional thereby stimulating the vestibular end
organs in a non-physiological manner. This unusual form of vestibular stimulation could lead to
very confusing percepts as central vestibular pathways do their best to resolve the nonphysiological
pattern of end organ stimulation resulting in sensations of physically impossible
motions, unexpected reflexive postural responses to them, and faulty inferences about external
forces causing them. Affected individuals could report different sensations in response to the same
external stimulus; thus, immediate reports of affected individuals may not be veridical and
sensations may vary from one individual to another. If a Frey-like effect can be induced on central
nervous system tissue responsible for space and motion information processing, it likely would
induce similarly idiosyncratic responses.

National Academies of Sciences, Engineering, and Medicine 2020. An Assessment of Illness in U.S. Government Employees and Their Families at Overseas Embassies. Washington, DC: The National Academies Press.