Upgrading electromagnetic shielding of a military shelter

When equipped with EMI (electromagnetic interference) kits, a family of standard shelters built for the Department of Defense (DoD) provides approximately 60 dB of shielding to a plane-wave electric field (377 /spl Omega/). In an effort to upgrade the level of electromagnetic shielding from 60 to 80 dB, one of the shelters was redesigned with only minor changes in the design. An innovative design technique was conceived for sealing seams; for this technique, a preliminary laboratory test showed over 100 dB of shielding when the shielded enclosure is exposed to a plane wave at 1 GHz.