It shall be unlawful to operate or cause to be operated any electrical equipment within a radius of ten miles of the reception equipment of any radio astronomy facility, if the instantaneous peak field strength of the emanation from such electrical equipment is in excess of:

Ten microvolts per meter measured at a distance of ten feet from such electrical equipment, if such electrical equipment is located less than three miles from said reception equipment; ten microvolts per meter measured at a distance of fifteen feet from such electrical equipment, if such electrical equipment is located less than four miles from said reception equipment; ten microvolts per meter measured at a distance of twenty feet from such electrical equipment, if such electrical equipment is located less than five miles from said reception equipment; five microvolts per meter measured at a distance of fifty feet from such electrical equipment, if such electrical equipment is located less than six miles from said reception equipment; six microvolts per meter measured at a distance of fifty feet from such electrical equipment, if such electrical equipment is located less than seven miles from said reception equipment; seven microvolts per meter measured at a distance of fifty feet from such electrical equipment, if such electrical equipment is located less than eight miles from said reception equipment; eight microvolts per meter measured at a distance of fifty feet from such electrical equipment, if such electrical equipment is located less than nine miles from such reception equipment; nine microvolts per meter measured at a distance of fifty feet from such electrical equipment, if such electrical equipment is located less than ten miles from said reception equipment: Provided, however, That notwithstanding the provisions of this section, it shall not be unlawful to operate or cause to be operated any electrical equipment so constructed or shielded as not to cause interference with the reception by such radio astronomy facility of radio waves emanating from a nonterrestrial source.