Another EMP question: Directional usage...

[Aro]

I realise there have been many threads on this topic (such as this), but I can’t seem to find an answer to my question:

Is an EMP directional? Or does any such device work as a point source and disrupt technology in all directions, spherically?

Say, can a weak EMP device be used like an anti-aircraft device, directed only upwards if only enemy aircraft are in flight? Or would such a blast also knock-out all electronics on the ground?

[Chronos]

Usually, when folks are talking about EMP, it’s from a nuclear explosion. In that case, it’s omnidirectional. It’s also not used in military situations because nobody wants the political repercussions of using any sort of nuclear weapon.

There are other ways to produce an EMP, and some of them are directional. However, I don’t think any of them are powerful enough, yet, to be practical.

[scr4]

I assume you are talking about non-nuclear electromagnetic weapons (usually called “high-powered microwave weapons”). From this Washington Post article:

Microwave weapons today come in what Schamiloglu calls “two flavors.” One, known as an “ultrawide band” weapon, uses an explosion to provide one quick, powerful burst of radiation over a broad range of frequencies. The likeliest method of delivery is via cruise missile, which can get the weapon close to the target without infecting friendly electronics.
…
More useful for specific targets are the second “flavor” of weapons, known as “narrow band” microwaves. Their characteristics are not publicly known, but Schamiloglu said machines rather than bombs would deliver them…

So apparently there are no directional microwave weapons, and the currently favored way to make it selective is to limit the bandwidth, not spatial distribution.