It's covered in Russian Patent No. 2,526,478 "Method and Device of Microwave Electromagnetic Impact at Trespasser"
"The technical result is achieved by the fact that it is proposed to use directional radiation modulated by amplitude of the microwave electromagnetic waves. The impact on the intruder is due to the occurrence of painful mechanical thermoelastic phenomena in individual elements of the human auditory apparatus at their resonant frequencies"
"The technical result is achieved by the fact that it is proposed to use directional radiation modulated by amplitude of the microwave electromagnetic waves. The impact on the intruder is due to the occurrence of painful mechanical thermoelastic phenomena in individual elements of the human auditory apparatus at their resonant frequencies"
https://patents.google.com/patent/RU2526478C2/en http://www.gbppr.net/mil/havana