When U.S. diplomats began mysteriously falling ill in Havana in 2016, scientists were perplexed by the cause. Until they realized that the cause was probably a microwave weapon that bathed the target in deadly radiation.
Now the U.S. military wants a sensor that will alert soldiers when they are being attacked by microwave weapons. Because soldiers may not even realize they are under attack by a beam that is invisible to the eye, but painfully apparent to the brain.
The Defense Health Agency (DHA) is looking for a wearable sensor that will detect radio-frequency (RF) weapons, which project intense beams of electromagnetic energy, including microwaves. RF weapons are already being developed by several nations. The U.S. has developed microwave weapons to shoot down drones, or as non-lethal crowd control devices. There are also reports that China might have used microwaves against Indian troops in 2020.
Yet because radio-frequency weapons are largely unknown and untested, soldiers may not even know they are under attack. “Without known patterns of RF injury to guide diagnosis, it will be difficult to differentiate RF injury from other common sources of illness and injury such as heat stroke,” according to the DHA research solicitation. “This ambiguous symptomology is aggravated by the transient nature of RF energy. Without a sensor it is possible that no residual evidence of RF attack will be available.”
Indeed, the U.S. government initially dismissed reports that U.S. diplomatic and intelligence personnel were suffering from headaches, nausea and ringing in the ears. Since 2016, when personnel at the U.S. embassy in Havana first reported symptoms, ailments have been reported by U.S. diplomats and intelligence agents stationed in Russia, China and other nations. Were these caused by some natural ailment, or hostile action by foreign governments? And if hostile, what was the cause?
Eventually, suspicions turned to microwaves, whose effects on the human brain were discovered in the 1960s. “Directed pulsed RF energy, especially in those with the distinct early manifestations, appears to be the most plausible mechanism in explaining these cases,” concluded a National Academy of Sciences study in 2020.
Beyond headaches and vertigo, RF weapons can actually damage the human nervous system. In 2014, the National Security Agency admitted that one of its officials might have been harmed by a microwave attack in the 1990s.
Not surprisingly, the Pentagon worries that a directed energy weapon used against embassies could also be used against soldiers. A wearable sensor would let troops know they’re under attack, giving them to take cover or neutralize the weapon before they suffer injury.
But wearable sensors pose challenges: they have to be small and light enough to be easily carried by already-overburdened soldiers, and they need to sip power to preserve their batteries. Indeed, DHA lists an “extremely small footprint in terms of space, weight and power (SWaP),” to be the most important factor, followed by low cost, a low false positive rate, and a display that can be easily interpreted by users.
DHA actually seems to be envisioning a relatively simple device smaller than the magazine of the M4 rifle. The agency compares the RF weapon detector to M8 and M9 paper used to detect the presence of chemical weapons.
Interestingly, it turns out that people are less vulnerable to radiation than electronics. “Because irradiance levels needed to injure personnel are orders of magnitude higher than required to damage electronics, designing a broad band absorber with appropriate response characteristic will require substantial innovation,” DHA noted.
Phase I of the project calls for determining the effects of microwave radiation on humans, and conceiving a design for the device that includes an antenna that can survive intense radiation. Phase II calls for a prototype, followed by a Phase III transition to users such as the Air Force Medical Readiness Agency’s Advanced Development Office or the Army’s Program Manager for Soldier Survivability.
Perhaps the most significant aspect of this project is what it says about the future battlefield. Directed energy weapons, such as lasers and microwaves, had enjoyed an exotic aura. They were seen as tools for destroying ICBMs and drones, or for dispersing rioters. But the fact that the U.S. military wants its foot soldiers to detect microwave attacks suggests that these weapons may become a part of conventional warfare. Future battlefields are likely to be in difficult terrain, such as cities and tunnels, where an energy weapon might be just as useful as a rifle.