Jinx  wrote:
> A friend has been giving me grief for some
> few weeks about noise she says is coming
> from a microwave tower about 300m from
> her home

I'm sure she is not able to determine the direction of the ultrasound,
until, of course, she is a bat.
I am not about getting into  RF version here.

Most probably the sound is emitting inside her house.
It could be some old swollen battery or accumulator (say, from
cellphone) emitting air through the micro-hole or something similar.
It's hard but still possible to locate the aprox place in the room
where sound is at max amplitude on average.  Here she is to seek the
little screaming creature.

Regards,
MS
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