NMAC BTWN 2 SMA.

Narrative

I EXECUTED AN ILS APCH TO RWY 11 AT SJC IN IMC. AFTER BREAKING OUT OF THE CLOUDS (AT 2000 FT); I CANCELED MY IFR FLT PLAN (AT 1500 FT) WITH SAN JOSE TWR AND REQUESTED A VFR CLRNC DIRECT TO RHV. SAN JOSE TWR GRANTED MY CLRNC; TOLD ME TO 'SQUAWK 1200;' AND I FLEW A HDG OF APPROX 100 DEGS TOWARDS RHV. I HAD NEVER FLOWN TO RHV BEFORE; BUT I HAD DONE ADEQUATE PREFLT PREPARATION. I ALSO HAD A PANEL- MOUNTED GPS ON BOARD; SET ON 'DIRECT TO RHV.' AT ABOUT 7 MI OUT; I CONTACTED RHV TWR AND REQUESTED 'LNDG WITH PAPA.' LISTENING TO THE ATIS TOLD ME THAT RWYS 13L&R WERE ACTIVE. I WAS EXPECTING CLRNC FOR RWY 13R; SINCE I WAS COMING FROM THE W. THE TWR TOLD ME TO 'SQUAWK XXXX' AND 'MAKE STRAIGHT IN FOR RWY 13L.' BECAUSE OF THE XPONDER CODE; I MADE THE ASSUMPTION THAT THE TWR HAD ME ON RADAR; AND I QUERIED THE TWR 'WAS THAT RWY 13R OR RWY 13L?' THEY REPLIED 'RWY 13L; AND YOU'RE #2 BEHIND THE CESSNA ON DOWNWIND; ABEAM THE NUMBERS.' I LOOKED AHEAD AND TO MY L; AND SAW NOTHING. I THEN TURNED ON MY LNDG LIGHT AND TAXI LIGHT FOR INCREASED VISIBILITY TO OTHER ACFT. I LOOKED AHEAD AND TO MY R AND SAW AN ACFT IN THE TFC PATTERN WAY AHEAD OF ME AND BELOW ME; TURNING FINAL. I COULDN'T DETERMINE IF HE WAS LINED UP FOR 13 R OR 13 L. I ASSUMED THAT HE WAS THE ACFT THAT I SHOULD BE FOLLOWING. I ALSO KNEW THAT I WAS ON THE TWR'S RADAR; AND I DIDN'T HEAR ANY OTHER RADIO CALLS ON THE FREQ. SUDDENLY; APPEARING JUST OVER MY L SHOULDER WAS A CESSNA; DSNDING AND MERGING INTO MY FINAL APCH PATH. I ESTIMATE THAT HE WAS 50 FT ABOVE ME; AND 150 FT BEHIND AND TO MY L AND CLOSING FAST. I IMMEDIATELY TOOK EVASIVE ACTION TO AVOID THE POSSIBILITY OF A COLLISION; BY DIVING AND MAKING A SHARP TURN TO THE R. I DID NOT HAVE TIME TO LOOK TO THE R BEFORE EXECUTING MY EMER MANEUVER. I IMMEDIATELY INFORMED REID-HILLVIEW TWR OF MY ACTION AND WHY IT WAS NECESSARY. I EXPLAINED THAT THERE WAS SOME CONFUSION ABOUT WHICH ACFT I WAS SUPPOSED TO HAVE BEEN FOLLOWING; AND THAT WAS WHY I WAS DIVERTING TO THE R. (A LEFT HAND TURN WOULD NOT HAVE BEEN POSSIBLE). MY INTENTION WAS THEN TO MAKE A R 360 DEG TURN AND SET UP FOR ANOTHER APCH. THE TWR WAS APPARENTLY UPSET WITH ;MY EVASIVE ACTION; AND ANNOUNCED THAT I HAD 'CUT ACROSS THE PATH OF ANOTHER ACFT ON FINAL FOR 13 R.' I NEVER SAW THIS OTHER ACFT; JUST AS THE CESSNA APPARENTLY NEVER SAW ME. THEN THE TWR GAVE ME CLRNC TO LAND ON RWY 13 R; WHICH I DID WITHOUT INCIDENT. IN MY OPINION; I PROBABLY SHOULD HAVE QUESTIONED THE TWR WHEN I DIDN'T SEE THE CESSNA WITHIN A FEW SECONDS AFTER IT WAS ORIGINALLY CALLED OUT TO ME. I ALSO FEEL THE TWR; WITH RADAR AT ITS DISPOSAL; SHOULD NOT HAVE EVER LET US GET THAT CLOSE IN THE FIRST PLACE. IT ALSO SEEMS THAT THE ABSENCE OF OTHER RADIO CHATTER ON THE FREQ COMPOUNDED THE PROB. I ASSUME THAT THE OTHER ACFT MAY HAVE BEEN ON THE 119.8 FREQ.