[Elecraft] wire antennas

[wsm at amaonline.com]

Hi
This is a little off topic, but I don't know of a better place to
find someone that would know the answer to my question.
Many years ago I used one coax to feed three different inverted V
antennas all for different bands. At the time I thought they worked
just fine. Worked all kinds of dx with the setup. I have been told
lately that the unused antennas on the setup would pick up additional
noise. 
Has anyone ever done any testing with multiple antennas on one
feedline to see if they really do pick up extra noise?
I'm thinking about putting up new inverted V antennas on 160, 80, and
40 meters and feeding them with one coax. Sure beats antenna
switching and it always seem to me that the signal would go to the 
resonate antenna. I always used a coaxial balun in the feedline.
Any ideas would be appreciated.
Thanks
Scott N5SM