Setting aside the obvious solution of using the phone's parental controls or physically confiscating the phones each night…
1) Is there a way to arrange omnidirectional transmitters so the signal is much stronger inside a given volume than outside it? Maybe using constructive/destructive interference like a Fourier transform?
2) Wouldn't a directional antenna dish on the roof pointed down keep the signal from leaking out so much?
3) Do cellular companies provide consumers with an API or webpage to scrape that shows data usage in near-real-time so he could have set up an alert if his kids break the rule?
Re (1) and (2), remember jamming is illegal even on your own property. So even if those ideas did work, you'd just be helping him get away with committing a crime.
I'm asking if there are ways to be more precise with radio emissions given omnidirectional antennae in the hypothetical case where the only restrictions are Mother Nature's, sort of like the question "can you arrange magnets to produce stable levitation?" (BTW: no unless they're electromagnets.)
1) Is there a way to arrange omnidirectional transmitters so the signal is much stronger inside a given volume than outside it? Maybe using constructive/destructive interference like a Fourier transform?
2) Wouldn't a directional antenna dish on the roof pointed down keep the signal from leaking out so much?
3) Do cellular companies provide consumers with an API or webpage to scrape that shows data usage in near-real-time so he could have set up an alert if his kids break the rule?