I don't know much about anti-particles and such. But I was thinking what if they made a magnitron that emitted anti-mircowaves? Would it take the heat out of the item in there or what?

Ever heard of Anti Matter?

Yes it's the opposite of matter so to speak right?

I don't think anit-microwaves are possible. Microwaves are radio waves that work by making protons in molecules vibrate. This is what causes things to get hot. You need to reverse this process in order to cool something down, and I don't think there's any form of radiation that can do this.

Just a couple cents for ya

I saw a "thing" on the Tomorrows World program about 6-7 years ago and it was a sort of reverse form of microwave. It rapidly froze the food that was placed inside.

Whether microwaves were involved or not, I do'nt really know?

Source, it could've been that, it was a while back. Just one of those nonsense things that stuck in my head. Cheers.

Radiation to cool things??? I think laser cooling fits into this category.