Which, of course, was the primary reason behind our construction of the two cages. In our case, we were trying to isolate birdies in our tuned cavities and needed the ambient rf levels to fall below the -115 dBm level. The only way you are going to accomplish that is with a cage. It is pretty easy to find and fix the birdies in equipment when you can isolate all transmission energy to just the equipment and not having to look at the intermod/multipath from a dozen Broadcast transmitters.

Are you sure you aren't talking about a lightening conductor? A Faraday Cage shouldn't need to be earthed; indeed a lengthy cable like that can make things worse.

No, no cable, copper bar stock sunk into a copper mesh sitting in a bed of mineral salt.

If the Faraday Cage is to prevent the energy from penetrating, it will have to shunt the charge to ground or some large capacitive sink that itself is isolated from pulse enough not to couple the field.

If you aren't going to shunt the charge to ground, then I suppose you could build a counter-pulse device that would bend the pulse similar to how the earth bends solar radiation toward and around the poles. It's tricky, though, as you'd have to sense the polarity of the incoming pulse, it's magnitude, and the direction of propogation, then be able to trigger the counter pusle at the right time. Hmm, that could be very interesting indeed.

Actually, to protect equipment from lightning, I would look to dissipate the ground charge using a heliac-type array, something similar to an umbrella frame but on a much large scale.

Any Faraday circuit I've worked with has been grounded for it to work, otherwise it becomes electrically tranparent to any emission.