[Simple Simon (OP)]

I am trying to estimate an effective range and power for a microwave weapon for a story. The idea is mainly something that short circuits electronics, and microwave radiation fields that ionize any missiles that come near. That, combined with a large spark coil, is intended to fry anything that gets near the radiation field, making an automatic point-defence system.

The question is, how powerful would this need to be? Initial estimates are at a 10kw microwave emitter, probably at the same frequency as a microwave oven. I'm not sure of exact wavelength, as I haven't been able to find good charts on attenuation lengths in air and other mediums.

I'm sorry if this question is not suitable for this board, I wasn't sure where or how I should put it. Thank you for any advice you can give.

[Atomic-S]

10 KW would no doubt take out any human intruder quickly. Electronic disruption may require quite a bit less. Ionization of missiles may require quite a bit more.

[Simple Simon (OP)]

Thank you Atomic S. I think you're right about ionization. Thinking about it more, I and a friend came to the idea that something like one second of exposure with a 10kw microwave laser may be enough to effectively build up enough charge to arc an electrical current to. Would you agree?

Thank you again.

[evan_au]

You can get arcing inside a domestic microwave oven, with a power of around 1kW.

But to create that same electric field in a missile which is perhaps 1km away would require considerably more power, and a very large antenna.

There was a story about a phased-array radar with a peak power output in the Megawatt range (short pulses).
It was built in a pyramid-style building near a military airport, and they had to turn it off whenever planes came into land, because there was a chance that if a plane flew through the radar beam, it might trigger the explosives that fire the ejector seat.

Phased-array radars can quickly scan the entire sky to search for missiles without physically moving. Then they could focus more power in one direction to target one object.

Missiles are hard to disrupt, because they are often sealed inside a metal case - although sensors like optical, infra-red and radar sensors must be exposed to the outside world.
See: https://en.wikipedia.org/wiki/Active_Phased_Array_Radar

Another possibility is a ElectroMagnetic Pulse device (EMP). This disrupts electronics - so you don't want to set it off too close to your electronics! And military equipment is designed to withstand EMP.
See: https://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator

[Simple Simon (OP)]

Thank you, Evan, that is good data. I spoke with someone on the subject, and it appears the radiation field idea won't work. The field would be so weak, or require so many gigawatts, that it would be pointless to attempt.

Evan's idea is the way to go. Classic point defence detects the threat then sends a focused beam at it. The question is whether you can build enough charge on the missile or plane to make it vulnerable to electricity (the civilization I'm working this out for uses electro-lasers).

Besides that possibility (which is the focus of a separate thread), there's the question of how well missiles and the like can resist strong masers. I do recall concern with a radio tower on a military base, that pilots weren't allowed to fly while it was active in case it caused the explosives in their ejection seats to fire. Calculating the effectiveness in microwaves in this roll would be difficult. I'm not sure what formula you would use.

[William McC]

10 KW would no doubt take out any human intruder quickly. Electronic disruption may require quite a bit less. Ionization of missiles may require quite a bit more.

I was told by someone that built microwave prototype weapons that helium was used, basically put through a flow valve in a quantity, to just maintain its presence in the aluminum horn, as it expanded and heated, in the microwave horn. To achieve much greater results from the same input power. That might be the weapon you are looking for.

Some of this fellows prototypes were capable of boiling the water off of a submarine. Which is usually the end for the submarine.

Sincerely,

William McCormick

[William McC]

Some of these advanced prototype microwave weapons were tested on dry land, causing the ground water to boil and explode with almost unbelievable destruction.


Sincerely,

William McCormick

[Simple Simon (OP)]

Wow... thank you Will, glad to know that terrifying microwave weapons are realistic. I will go and be terrified some as I reflect on that.

I never thought of microwaves being effective weapons underwater... the wavelengths I'm familiar with would react too much to water. This is... a very interesting discovery. I take it that these weapons could be used by say, submarines?

[William McC]

I do not believe that submarines use them or could use them, rather the prototype EA6B or prototype intruders had them. They had a 40 KW windjammer generator that was powered by a small hole that took in air from the planes movement and then output 40 KW for the jammer.

Sincerely,

William McCormick