The ALMA Project is developing a 66 antenna radio astronomy array on a 5000 meter mountain in Chile. Radio astronomy depends on a radio frequency quiet area. The remote mountain top is ideal for such a radio astronomy array. However, RFI from equipment inside one type of antenna had a path loss of 13 dB to its feed area, when measured at 100 GHz. Carbon filled foam is being used to enhance shielding to reduce the negative effect of local radio frequency interference (RFI). This foam has been measured and verified to be effective from 1 to 100 GHz.
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