4
$\begingroup$

Reading about Non-nuclear electromagnetic pulse (NNEMP) weapons that generate high-intensity electromagnetic bursts to frazzle electronics.

Now, when other kinds of electromagnetic wave are generated (e.g. WiFi), you can use an omnidirectional antenna, or a directional antenna which increases the power (and hence distance) of the signal.

My question is could an electromagnetic pulse be directed through an antenna of some kind like a Yagi antenna –

Yagi-Uda antenna

...or a helical antenna –

Helical antenna

Thank you

Improve this question
$\endgroup$
7
  • $\begingroup$ Can you be more specific? A laser is a very directional electromagnetic pulse... would that satisfy your request? $\endgroup$
    – L.Dutch ♦
    Commented Jan 26, 2023 at 16:49
  • 4
    $\begingroup$ Electromagnetic pulses do not fry microchips, at least not directly. What they do is they induce a large current in long conductors, such as power lines. If a microchip is connected to such a long conductor, then it fries. If it is not connected to such a long conductor, then it does not fry. (Yes, you can imagine an electromagnetic pulse strong enough to fry microchips directly; but in this case it will also fry the two meters long salt water conductor known as the human wearing the phone. Large humans are very much better than tiny phones at coupling with EM pulses.) $\endgroup$
    – AlexP
    Commented Jan 26, 2023 at 16:58
  • 4
    $\begingroup$ Oh, and you need to realize that all the energy of the EM pulse must pass through that antenna. Molten antennas are bad antennas. $\endgroup$
    – AlexP
    Commented Jan 26, 2023 at 17:01
  • 2
    $\begingroup$ Simply, "yes." An EMP is nothing more than a strong pulse of photons (radio, visible light, microwaves, x-rays, gamma rays, etc.). Traditionally we view it as an uncontrolled byproduct of a nuclear explosion - but using a radio station to jam radio waves is an "electromagnetic pulse." So, yes, certainly it can be made directional. How strong it must be to do the damage you want at the distance you want and whether or not the antenna can handle that (@AlexP's right about that) is another matter (if that matter). I'm thinkin' you should delete this question and ask something much more specific. $\endgroup$
    – JBH
    Commented Jan 26, 2023 at 17:31
  • 2
    $\begingroup$ BTW, if you search for "electromagnetic pulse" on this site, you'll find a LOT of answers (including several of mine, here's one of my favorites). In other words, there's a better-than-average chance your question could be a duplicate. Please review the search results first. Cheers. $\endgroup$
    – JBH
    Commented Jan 26, 2023 at 17:32

2 Answers 2

Reset to default
1
$\begingroup$

It is possible, but maybe not practical.

Consider a parabolic dish receiver. The idea is that signals arriving at the dish in a parallel path are concentrated on the focus. This works well for distant targets such as planets or stars. The light (or radio waves) coming from distant targets is extremely close to arriving in parallel paths. (Diagram from the wiki page.)

enter image description here

So if you put a radio wave source (such as the sort of thing that produces the microwaves in a microwave oven) at the focus, and point it at the dish, it will reflect and come out as a parallel beam.

The required size of the dish has to be many wavelengths or you don't get any useful area or reflection. So radio in the 1 cm range needs a meter-ish sized dish.

And there is the difficulty. Your source has to tolerate a density of radiation energy that is necessarily many times larger than in the beam. The dish can make the beam parallel, but spreads it out over a large area.

There is some limited ability to tweak the shape of the dish so you get a concentration at some distance. That is, instead of the beam going out parallel, it goes out converging. This is not a trivial task since it will require a complicated shape to get a good focus.

You could possibly arrange for it to be deformable, possibly controlled by some sort of servo mechanism, in turn run by a computer. Otherwise the focus will be at a fixed distance, and either farther or closer the beam will be very low energy density. This is getting to be a pretty complicated thing. And it's getting heavy.

Also, putting the source slightly in front of or behind the focus, you can make the beam converge or diverge, at the expense of spoiling the focus slightly. So you lose a little energy density but allow the beam to concentrate somewhat.

There are also limits on how concentrated such a thing can be. Basically, the limit is very roughly that you can't concentrate more than the source you started with. It's the old thing about a magnifying glass cannot concentrate light beyond a certain limit. Maybe that's enough for some purposes.

Improve this answer
$\endgroup$
0
$\begingroup$

The nearest think I can think of is the Duga radar, or 'Woodpecker'. This didn't fry electronics but it did disrupt radio transmissions, as well as serving as a radar source for a separate detector.

Death rays are rather hard to construct. A laser is reflected by a mirror unless the power is very high. even then, a lot of the laser power reflects off the plasma just above the surface. Electromagnetic pulses are shielded using a metal box. If you want to make your own Carrington event, and bring down wires, you are going to need a lot of energy. Not impossible, but probably nuclear-powered, which suggests a tried and true way of destroying lots of stuff.

Improve this answer
$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .