Electronic Alarms and Home Security Devices - Wireless camera and all steel building problem

I have a 50ft by 60ft all steel building with wireless cameras installed in it. As I suspected and verified, with the overhead door closed, I have no video reception.
Does anyone know of a way to cure this problem?
My thoughts are possibly using an antenna on the inside with a repeater to transmit using an external antenna. Does anyone know if such a device exists or perhaps know of a way I can accomplish this? Thanks. Mike

P.S. I have searched the internet with no luck finding anything.

No, there really isn't such a thing at the grade you are talking about.

Your only practical method is to use a wired camera connected to a transmitter with an antenna that's on the exterior of the metal shell.

Try some of these things:

http://www.supercircuits.com/Wireless-Devices/

Thanks a lot for the site that you sent. It looks like a couple of these things may do the trick for me and a reasonable cost.

Mike