Abstract Aspects of VLF Shielding Design and Fabrication

Summary form only given. VLF Shielding, below 10 KHz and down to 20-30 Hz, requires design considerations and unique fabrication and installation techniques. The lower the frequency of concern, the more critical the choice of materials and the fabrication and installation of these materials in the high performance VLF shielded room. Since the greatest design and fabrication is with respect to the magnetic component in VLF shielding, this presentation will cover elementary design and performance information with respect to the absorptive losses in both far field and induced near field conditions. All-important in design and fabrication considerations is the reluctance of joints, door seams and other penetrations. Also unique is the honeycomb type of air vents when used as a shield in induced magnetic fields. Power line filters present challenging problems when the frequency of shielding is in the pass band of these filters. VLF shielding and information on the above will be covered with equal attention to the design, selection of materials and fabrication. Illustrations will be given for typical applications for Tempest and EMP requirements.