Maybe you mean http://darkith.dyndns.org/~darkith/html/dbu_inst.shtml Goldenraven?

Panther G, what do you mean "shield" it. Do you mean shield it from IR shots from tanks (to make it harder to hit), or do you mean shield it from sunlight to stop false hits?
If it's sunlight, you could do as GoldenRaven suggest and build a baffle set for it. You could also try a piece of dark exposed film negative (if you can find any!). "A simple visible light filter can be made by cutting the dark portion off a developed 35mm film negative. This will absorb most of the visible light while passing the infrared signal through."
Even better is to do both...

Other solutions would be to scavenge a visible light filter from a TBU, HBU, or old remote control that has a dark "window" over the IR LED.

D.