Investigation of Shielding Methods and Materials for Reduction of Radiofrequency Interference to Backup Emergency Communication Equipment.

摘要

Backup emergency communication (BUEC) equipment operation in the field has been reported to be impaired by radiofrequency interference (RFI). This RFI enters the BUEC transceiver via its antenna as well as directly through imperfections in the internal shielding of the transceiver itself. Methods of reducing the effect of this RFI by shielding of the antenna and the transceiver itself were studied at the Elwood,New Jersey,Long-Range Radar Site. It was found that the radome catwalk deck itself was an effective shield against both ultrahigh frequency (UHF) and very high frequency (VHF) RFI,and that moving the antenna radially inward from the protective rail of the catwalk provided effective shielding. Additionally,it was found that UHF RFI generated by the common digitizer (CD) was completely eliminated by a 6X6-foot copper mesh screen interposed between the BUEC antenna and the CD,however,this means did not provide complete shielding for VHF interference. Finally,direct RFI leakage into the transceiver appears to be through the front end of the transceiver. (Author)