Hi Bob

I modeled a commercial install some years ago on 148MHz (pagers) that
ended up with maybe 3-4 nulls between 6 and 9dB on the shadow side. This
was also born out by a site/coverage test.

As it turns out the antenna mounting designers hit this as a pure fluke
or if you like plain old bad luck! Moving the antenna in or out maybe
10" yielded ripples less than 3dB. The reason we were even looking at
the pattern was that the coverage had gaps in the prediction off the
back of the mast. The modeling (nulls) actually matched the places where
the signal was low.

You can of course place an antenna for best gain off the mast as a
reflector of sorts. The URL below is an extended double 5/8 ZEPP with a
center hairpin feed that I more or less optimized for that.

http://pages.suddenlink.net/vk2yqa/f...0patter n.gif

F/B is about 6dB

Cheers Bob VK2YQA

Bob D. wrote:
I'm putting up a Diamond V-2000 (Omni directional 6m/2m/440) on my tower
with a side arm. I've been told to expect some degradation in the 'shadow'
direction. Just how bad will this be in dB? Any affect on other directions?