I was looking for some advice about communication antennas.  The legacy is setup to have one com antenna.  We want a capable IFR airplane and I am hesitant to have one antenna with a diplexer (or is it duplexer, I've seen it both ways) as a possible single point of failure.  Is this the method that most people are using?  If you mounted a 2nd com antenna, where did you place it?  I searched the archives and found someone else who asked the same question but I couldn't find the answer.  Any other input or advice on the subject would be appreciated.

Dean Whiting