PBI: Microwave ovens and radar

[pmulcahy11b]

Microwave ovens are descendants World War 2 magnetrons, designed to make compact radar sets. So does a microwave oven cause a radar trace when it's heating up food? Can it be sort of sideways-engineered back into a working radar? Could they be turned into a GSR setup to at least detect vehicles?

[StainlessSteelCynic]

As I understand it.
1. No - different frequency band to those used by RADAR (but it will mess with other devices using frequency bands similar to the microwaves magnetron, apparently it'd work like a crude jammer).
2A. No - Short Answer; not enough output, it needs to be able to pulse transmit, it needs a receiver and someone smart enough to tune it all (and also a bunch of other parts)
2B. No - Long Answer; http://www.ar15.com/forums/t_1_5/941...ave_oven_.html http://www.thenakedscientists.com/fo...p?topic=7651.0

[WallShadow]

Here's a semi-related question: would an unplugged, magnetron-disabled microwave oven shell serve as an expedient Faraday cage? or would it have to have to be grounded?

[StainlessSteelCynic]

A microwave oven actually uses a type of Faraday Cage however it is optimized for keeping the microwave radiation inside the oven. This does mean however, that it will block the same frequency of radiation from getting in.
As I understand it, the magnetron does not need to be disabled but unplugging the oven from the socket is probably a good idea to prevent power surges possibly causing the magnetron to activate (and frying whatever you had inside!) because the magnetron controls etc. etc. are on the outside of the Faraday Cage and they will be effected by any electrical or radiation surge.
Keep in mind that I do not know for a fact that EMP blasts could do this, it was an unsupported claim I read somewhere that an EMP induced power surge could cause your electrical devices to activate for a few seconds before they short out.

The word cage gives the idea that there are openings in the cage material but for a Faraday Cage, this is not actually necessary and if they do have any openings, they need to be related to the frequencies you're trying to block. Hole size will block certain frequencies and I believe it's a case of smaller hole size is better. With a microwave oven, the hole size in the Cage is not particularly small - look at the viewing window on the oven and you'll see the embedded mesh that makes up one side of the Faraday Cage.
To get an idea of what I mean by all of this, try the following: -
1. turn off & unplug your microwave oven
2. make note of the reception strength of your mobile/cell phone (how many bars)
3. put your mobile/cell phone inside the oven
4. check the reception strength again and see how many bars are blocked by the oven
5. try the same thing with another mobile/cell phone running on a different phone network and compare the results

A microwave oven is optimized to stop a small range of radiation frequencies, some phone networks will be blocked by the oven while others using different transcieving freqs will suffer reduced connection but not be entirely blocked because the oven is not optimized to block those specific freqs.

A typical man-made EMP will spew out a massive range of freqs so a microwave will stop some, reduce others and probably not stop the rest.
The best defence from EMP is to have your devices in nested Faraday Cages but the cages must be insulated from each other.

If you are only trying to stop radiowave type radiation, even something as simple as wrapping your devices in heavy duty aluminium foil (make sure there are no gaps!), enclosing that package in any non-conductive material (e.g. rubber, plastic, wood) and then securing that inside another Faraday Cage (such as a microwave oven) will allegedly protect the device.

For maximum effect, apparently the best thing to do is place your aluminium foil wrapped items inside a heavy duty plastic bag, wrap that in more foil, place that package inside another heavy duty plastic bag and then wrap that in another layer of foil. Then place all of that inside your Faraday Cage.

Keep in mind that the outside Cage must be grounded if you wish to protect against electrical surges but it is not necessary to ground the Cage if you are only trying to stop radiowave type radiation.


Now...
Keeping in mind that radiation travels in direct line of sight, a modern safe with inner flanges to prevent the door from being jimmied open will apparently work as an ad hoc Faraday Cage as long as you block up any gaps with suitable radiation blocking material and again, if you're trying to stop electrical surges, the safe would need to be effectively grounded.
However, always keep in mind that the outside Cage should be made of the best electrically conductive material you can get - the steel of a safe is helpful but not as useful as copper sheeting.

Resources:
These are the websites I trawled through to get some idea of all this - Warning! It entails lottsa reading!
http://modernsurvivalblog.com/emp-el...-faraday-cage/
http://www.thenakedscientists.com/fo...?topic=41755.0
http://www.futurescience.com/emp/emp-protection.html
http://www.thehighroad.org/archive/i.../t-344280.html
http://www.preparednesspro.com/many-...-faraday-cages
http://boards.straightdope.com/sdmb/...d.php?t=557413

[rcaf_777]

Found this Radar System for sale, I'm guessing you still need the dish and all its parts and a power source

http://www.recycledgoods.com/decca-r...ar-system.html

[Silent Hunter UK]

Could you use a satellite dish for that?

[swaghauler]

Originally Posted by Silent Hunter UK

Could you use a satellite dish for that?

No. for the older (not digital/solid state) radars, you need a rotary emitter in a particular range band. ironically, the "armature" that emits the radiation inside a microwave (the little "T" shaped spindle located on top of or underneath the cooking surface) is designed exactly like a pulse radar's emitter. It's just a bit too small for that application.

For determining the detection range of a radar target you can use the following equation:

(1.22 Nautical Miles X the square root of the radar emitter's height off the water) + (1.22 Nautical Miles X the square root of the radar target's height off of the water) = Detection Range in Nautical Miles

If you want more information on radar (especially small Marine Radars), check out West Marine's Q&A on marine radars for more information on old school "pulse radars," "digital solid state," and "new wave" hybrid radars.

[CDAT]

Just out of curiosity what does the PBI in the title stand for? I have only ever seen it stand for Poor Bloody Infantry.

[ArmySGT.]

Originally Posted by pmulcahy11b

Microwave ovens are descendants World War 2 magnetrons, designed to make compact radar sets. So does a microwave oven cause a radar trace when it's heating up food? Can it be sort of sideways-engineered back into a working radar? Could they be turned into a GSR setup to at least detect vehicles?

To add to this ....... Can one be used as a cheap and expendable jammer? How much area could you blanket with electronic noise if it does work?

[rcaf_777]

Originally Posted by Silent Hunter UK

Could you use a satellite dish for that?

Maybe, this radar system is an S Band radar. The S band is used by weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station. The 10-cm radar short-band ranges roughly from 1.55 to 5.2 GHz.

https://en.wikipedia.org/wiki/S_band

If your trying to use it as surface ship radar I'm guessing you will need something like this

https://www.kelvinhughes.com/maritim...vigation-radar