https://foreignpolicy.com/2021/05/10/microwave-attacks-havana-syndrome-scientifically-implausible/

Here’s the problem. Aside from the reported syndromes, there’s no evidence that a microwave weapon exists—and all the available science suggests that any such weapon would be wildly impractical. It’s possible that the symptoms of all the sufferers of Havana syndrome share a single, as yet unknown, cause; it’s also possible that multiple real health problems have been amalgamated into a single syndrome.

It’s not the first time microwaves and embassies have mixed. From 1953 to 1976, the U.S. Embassy in Moscow was bathed in high-powered microwaves coming from a nearby building. The purpose seems to have been related to espionage—activating listening devices within the embassy or interfering with American transmissions. But a 1978 study concluded that there were no adverse health effects.

Typically, to independently power a microwave oven you would need a 2,200-watt gasoline-powered generator, which would weigh around 50 pounds and measure 11 by 18 by 20 inches. For a hypothetical microwave weapon, the microwave-generating part of the weapon might be another 10 pounds heavier than that and require a similar or larger volume. If batteries were used instead of a gasoline generator, something like 200 laptop computer batteries would be needed to power the weapon.

The range of such a weapon would depend on wavelength, whether the microwave frequencies are pulsed or continuous, and the waves’ collimation, along with the materials between the weapon and its target—a range that would have to be closer to tens of feet than hundreds. A gasoline-powered model could fit in a backpack carried by a strong person. Either a gas-powered or battery-powered model might fit in a van, and definitely in a building. But all of these would be difficult to use unnoticed, or to target individually