▁used ▁by ▁scientific ▁experiments ; ▁ ▁a ▁cross - d ip ole ▁turn st ile ▁anten na ▁for ▁the ▁transmission ▁of ▁te lem etry ▁on ▁a ▁frequency ▁of ▁ 1 3 7 ▁M Hz . ▁ ▁The ▁scientific ▁experiments ▁are : ▁▁▁ 4 ▁R yle - V on berg ▁rad iom eters ▁analyz ing ▁frequencies ▁between ▁ 0 . 4 5   M Hz ▁and ▁ 9 . 1 8   M Hz ; ▁▁ 2 ▁multi - channel ▁rad iom eters ▁analyz ing ▁frequencies ▁between ▁ 0 . 2 ▁and ▁ 5 . 4   M Hz ; ▁ ▁An ▁imped ance ▁pro be ▁associated ▁with ▁ 5 ▁anten nas ▁analyz ing ▁frequencies ▁between ▁ 0 . 2 4   M Hz ▁and ▁ 7 . 8 6   M Hz ; ▁ ▁A ▁capac itive ▁pro be ▁associated ▁with ▁the ▁di pole ▁anten na ▁analyz ing ▁frequencies ▁between ▁ 0 . 2 5   M Hz ▁and ▁ 2 . 2   M Hz . ▁ ▁Results ▁The ▁following ▁results ▁are ▁reported ▁in ▁ 1 9 7 1 : ▁▁ ▁Ab solute ▁spectrum ▁and ▁average ▁cos mic ▁noise ▁up ▁to ▁the ▁frequency ▁ 0 . 5   M Hz . ▁ ▁Collection ▁of ▁radio ▁data ▁transm itted ▁during ▁type ▁III ▁solar ▁radio ▁burst s ▁in ▁the ▁ 0 . 2   M Hz - 5   M Hz ▁frequency ▁band . ▁These ▁elements ▁made ▁it ▁possible ▁to ▁obtain ▁a ▁first ▁estimate ▁of ▁the ▁solar ▁cor ona ▁electron ▁density ▁gradient , ▁the