How do i create a microwave defense system?

for protecting the one long hallway that leads to a highly secure server farm. i'm thinking of using thousands of magnetrons from commercial grade microwave ovens, my question is what is a better microwave antenna i can use for this application? will this affect the buildings power factor? this is real and i have been contracted to devise a strategy to do so and install it. it will be made of concrete with custom engineered wave guides in all directions. i can not divulge the method of access control. i need the name of the specific antenna, and how i can obtain this item in large quantity's.