more questions about buried PCB capacitors

Eric Bracken (bracken@ansoft.com)
Mon, 10 Jun 1996 15:05:28 -0400

As someone remarked, it seems reasonable to suppose that the sandwich
of two power planes behaves as a "radial transmission line". When you
inject current somewhere, a circular wavefront should move away from
the point of injection.

How does the amplitude of the radiated wave "die off" as it travels?

>From what I can tell, it's not dropping "nicely" like 1/r or log(r),
but rather as something very, very nasty.

It would be interesting to know the answer, since this radiated wave
might be able to upset the supply levels of nearby components
connected to the same power-ground sandwich.

I'm curious if anyone has better training/insight/empirical evidence
here...

--Eric

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