B737 CREW LOST BOTH THE CAPT'S AND FO'S LOC AND GS SIGNALS IN IMC IN ATL CLASS B ON VECTOR TO FINAL.

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WHEN BEING VECTORED FOR THE ILS APCH TO RWY 9R IN ATLANTA; THE COPLT'S ILS FAILED. BOTH LOC AND GS FLAGS WERE IN VIEW. WE SELECTED THE 'A' AUTOPLT SO THAT HE COULD COUPLE THE AUTOPLT TO THE CAPT'S ILS. WHILE ON A VECTOR OF 060 DEGS TO INTERCEPT THE LOC; WE NOTICED THAT THE ADF NEEDLE WAS NOT FALLING OFF TO THE L AS WE EXPECTED AND THAT THE CAPT'S LOC WAS NOT CAPTURING. SUDDENLY BOTH LOC AND GS FLAGS APPEARED ON THE CAPT'S ADI. I CALLED APCH AND RPTED A LOSS OF ALL NAV INSTS. HE IMMEDIATELY GAVE US A VECTOR TO THE SE (BACK TO THE LOC). AS HE WAS ASKING US THAT TYPE OF APCH WE WANTED TO FLY AND WE WERE TRYING TO ASCERTAIN WHAT TYPE OF APCH WE COULD FLY; THE CAPT'S ILS CAPTURED THE LOC AND GS. WE TOLD APCH WE COULD CONTINUE WITH AN ILS AND PROCEEDED TO LAND; BUT AFTER COMING OUT OF THE CLOUDS; WE AGAIN LOST ALL ILS NAV. AFTER REACHING THE GATE; OUR MECHS INVESTIGATED THE SYS AND FOUND A SERIOUS PROB WITH THE NAV ANTENNA THAT THEY WERE NOT ABLE TO CORRECT. BECAUSE OF THE CURRENT AND FORECAST CEILINGS AT OUR NEXT 2 CITIES; OUR FLTS WERE CANCELLED AND THE ACFT GNDED UNTIL PARTS COULD BE FOUND. WE DID NOT RECEIVE ANY TFC CONFLICTS ON TCASII; BUT RECOGNIZING THE LOSS OF OUR NAVAIDS TOOK SO LONG THAT WE MUST HAVE BEEN CLOSE TO A CONFLICT.