AM Daytime DX

[Rick Levy <Radiowaves@CompuServe.COM>]

>>...someone expain the following:
In Boston (South End/Downtown) I can receive CHSJ/700 StJohn,NB ("Country
700) VERY well, and can aslo get, although less well CHTN/720
Charlottetown PEI (Oldies Station) but once I leave the city proper
heading back to NH can no longer pick up...<<
         
Three words tell it all: salt water path.  The conductivity of sea water
is very high for groundwave signals such as these, compared to just about
any land path.  The FCC curves show that at 700 kHz, more attenuation
takes place in five miles of New England soil and rock, then in 300 miles
of sea water.  That's why these maritime signals don't get very far
inland, at least not in the daytime. 

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