I agree with you. There was a cascade of low efficiency stages. Making UHF sound in electrical form - a wave train - into a speaker or transducer to couple to t

I agree with you. There was a cascade of low efficiency stages. Making UHF sound in electrical form - a wave train - into a speaker or transducer to couple to the air = overall efficiency of 3-4%. Beam into the air as well focussed as possible - 10 feet away, less than 25% there. Turn that sound into electricity with another transducer with 3-4% efficiency = over all under 1%. So a honking great ultrasonic horn using 10,000 watts of power will transmit around 10 watts of usable power. The whole area will become an ultrasound cooker(you dare not walk through the beam = dead and cooked if you stayed for long, blood clots in a second or less. and for a large area bats will hate it and dogs howl