I was sent  a copy of a technical article last night that was a pdf 
file.  I tried to open it in accrobat, but was told the files was 
empty.  This was because the entire article was graphical.  I just 
read it using k1000.  Not perfect, but now I know a lot more about 
how to build a windom antenna than I did before.  Thinking of trying 
it this spring.