SMA PVT ACFT ON IFR FLT PLAN ENCOUNTERED ICING WHICH RESULTED IN BREAKING OFF THE NAV ANTENNAE. UNABLE TO FLY AN INST APCH THE TRACON VECTORED RPTR PLT TO A VFR ARPT.

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I WAS FLYING A TRIP FROM LOUISVILLE; KY; TO DENVER; CO; WITH A FUEL STOP AT TOPEKA; KS. THE LOUISVILLE-TOPEKA LEG WAS UNEVENTFUL; BUT I DID NOTE ACTIVITY DEVELOPING W OF TOPEKA WAS APPEARING ON THE STORMSCOPE WHEN I WAS APCHING TOPEKA. MY ATTN DURING THE DUATS WX BRIEF FOR THE TOPEKA- DENVER LEG WAS FOCUSED ON DETERMINING WHERE THE TSTM ACTIVITY WAS AND WHICH WAY IT WAS MOVING. I ALSO CONSULTED A DTN WX CTR COMMERCIAL WX RADAR DISPLAY. ALL OF THAT PLUS THE STORMSCOPE AND CONSULTING WITH FLT WATCH ALLOWED ME TO AVOID THE KANSAS TSTMS. ABOUT 100 MI E OF DENVER; I FLEW INTO CLOUDS AND SOON NOTICED CLR ICE RUNNING BACK FROM THE LEADING EDGE. I REQUESTED LOWER AND THE ICE MELTED. APCHING DENVER; I HAD TO CLB TO CLR TERRAIN AND IMMEDIATELY BEGAN TO ACCUMULATE CLR TO MIXED ICE. I DETERMINED MY BEST ALTERNATIVE WAS TO CONTINUE TO DENVER. WHEN I WAS VECTORED ONTO THE LOC AT APA; NEITHER COURSE DEV INDICATOR WAS STABLE ENOUGH FOR NAV DESPITE BEING ABLE TO IDENT THE SIGNAL. I SUSPECTED ICE WAS INTERFERING WITH NAV RECEPTION AND ABANDONED THE APCH. DEN APCH SAID BJC (20 MI NW) WAS RPTING VFR CONDITIONS WITH SCATTERED CLOUDS. I WAS VECTORED TO BJC AND LANDED UNEVENTFULLY. WHEN I DEPLANED I WAS STUNNED TO SEE THAT ICE HAD SNAPPED OFF BOTH EARS OF THE NAV ANTENNA. I GUESS ICE IS WHERE YOU FIND IT.