I imagine the conclusion of the book was that the microwave was used to send energy to a listening device inside the ambassy? (same technology as the contactles

I imagine the conclusion of the book was that the microwave was used to send energy to a listening device inside the ambassy? (same technology as the contactless smart cards used in public transport) A famous instance of this is 'the thing' : https://en.m.wikipedia.org/wiki/The_Thing_(listening_device)