How long until current 'stealth' techniques are compromised?

Yes, you are talking about a theoretical ADW "aerial denial weapon"
that would knock aircraft out of the sky without knocking out powered
systems on the ground.

Actually I was talking about something much different.
Lets consider a multi static system using hundreds or thousands of commercial
emitters and only a dozen or so powerful dedicated military emitters.If you can
detect and track a stealth platform (or any platform) , these military emitters
could be used as frequency and phase controlled combined devices to produce
much higher levels of energy at the target area.
Problem is phase locking but seemingly solved.
Such a device will not be able to engage targets at exotic ranges,wont be able
to recover GW or TW levels energy at target like EM Missilles and they are
strictly line sight type devices, but they will severely degrade the any
adversaries ability to attack.
And most importantly they are very cheap in comparison to "real" HPM weapons.