PA28 PLT ENTERED DC ADIZ WITHOUT CLRNC OR A DISCRETE XPONDER CODE.

Narrative

I DEPARTED 58N VFR WITH FLT FOLLOWING TO FDK; WHERE I STOPPED FOR FUEL. MY DEST WAS EQY; AROUND 300 NM TO THE SW. ALTHOUGH I ALWAYS PREFER TO USE FLT FOLLOWING ON THIS OCCASION THE HEAD WIND RPTED AT MY USUAL CRUISING ALTS (6 TO 12000 FT) WAS 45 TO OVER 60 KTS; SO I ELECTED TO STAY LESS THAN 3000 FT MSL UNTIL TERRAIN REQUIRED A HIGHER ALT. OFTEN AT THESE LOWER ALTS; ATC IS UNABLE TO PROVIDE RADAR SERVICE SO I DID NOT PLAN TO CALL THEM UNTIL I WAS AT A HIGHER ALT. I KNEW THAT THERE WERE ADDITIONAL FLT RESTRS IN THE AREA OF WASHINGTON DC (ADIZ) AND CONSULTED MY CURRENT VFR SECTIONAL TO AVOID VIOLATING THEIR AIRSPACE. ALTHOUGH MY SECTIONAL DESCRIBED UP TO 15 NM RESTRS FROM THE WASHINGTON VOR; I KNEW FROM MY BRIEFINGS THAT DAY (AND OTHER RECENT TRIPS ALONG THE SAME ROUTE); THAT THIS WAS EXTENDED TO 30 NM. I BELIEVE I HAD CAREFULLY PLANNED TO REMAIN MORE THAN 30 NM FROM THE VOR. I DEPARTED VFR WITHOUT ATTEMPTING TO OBTAIN FLT FOLLOWING AND USED MY RECENTLY INSTALLED GPS TO AVOID THE CLASS B AIRSPACE. MY PLANE HAS DUAL COMS; ONE WITH A VOR RECEIVER. ON THE FLT FROM 58N TO FDK; HARRISBURG APCH INFORMED ME THAT MY #1 RADIO WAS HARD TO READ; THOUGH RECEPTION SEEMED FINE. I USED MY #2 RADIO TO COMMUNICATE AND #1 TO MONITOR 121.5; THOUGH I WAS HEARING ONLY STATIC ON THAT FREQUENCY. I WAS ABLE TO RECEIVE ATIS WELL AND THOUGHT THE STATIC I HEARD WAS FROM THE SOURCE. ONCE CLR OF THE TFC PATTERN AND ENRTE 15 OR 20 MINS; I DECIDED TO TRY TO DETERMINE IF MY #2 RADIO ALSO RECEIVED STATIC ON 121.5. I WAS SHOCKED TO HEAR THAT THE XMISSION ON GUARD SEEMED TO BE DIRECTED AT ME AND IMMEDIATELY FOLLOWED THEIR COMMAND TO FLY W; AWAY FROM THE DC AREA. CONTRIBUTING FACTORS: MY MISINTERPRETATION OF THE BOUNDARIES OF THE ADIZ. MY SENSE OF NOT BEING IN VIOLATION AS I HAD DONE THIS TRIP A NUMBER OF TIMES WITHOUT INCIDENT (BUT ALWAYS WITH FLT FOLLOWING). FAILURE TO FILE A FLT PLAN. MALFUNCTION OF #1 RADIO; INITIALLY UNRECOGNIZED. CORRECTIVE ACTIONS: A MORE THOROUGH REVIEW OF AIRSPACE AND FLT PLANNING AND CORRECTION OF ALL FACTORS ABOVE. PERHAPS THE VFR SECTIONAL SHOULD BE MORE CLR IN A WARNING REGARDING THE ADIZ.