My working experience tells me that having a datacenter inside a Faraday cage is a VERY BAD idea.
¿Why? Well, just assume that you are the administrator of critical systems inside a steel reinforced, secure entry system with fingerprint, video, photos, secure card, daily code, one steel door, another security glass conductive door..
Ok, now you have a problem with the hardware of the system, or you might need to physically reboot it. No problem, it is in your own building: you go and get to solve the problem.
If you have no problems you can't/don't know how to fix, ok, but if you have problems, you can't phone your buddies so they remotelly help you: no phone. Ok, you might have one in the control room, but now you are maybe 100m away from your server.
If you send an operator, he will have the very same problem: no communication. So if problems arise, you might have him 80% or more of the time walking instead of solving the problem.. and you will go to the server yourself if you are not far from it.
Let's say that you want to have online help with your laptop near the server, using 3G for internet.. no luck, remember, faraday cage. the same goes for your Gold harware service technician...
I have worked in those conditions, and while you CAN still work, it is a less than desirable method of solving problems.
As for having high frequency transmissions inside a room filled with servers.. great, more RFI.. what you need is using optic cable to get rid of noise, not putting radiating antennas!! you might increase the error rates of your systems.. and that is really not desairable!! Also, if you use radio frequency connections, these connections have a greater error rate than cable ones, and retries might introduce jitter, and this is a big problem if you use those connections to manage high availability/replication/clusters... your systems might stop for sync!!
The solution is clear: you need an on rack switch, they are sold for a very good reason. Also, machines designed for housing blades also usually come with an internal switch for the very same reasons.. even if it is sometimes a bit underpowered.