On 12 Jan 2006 19:14:19 -0800, "
wrote:

I can keep the radio antenna at least 3 feet away from the
GPS antenna by keep them in either side of the T-top.

That works.

But I don't see
how I can avoid mounting the radio antenna near an metallic object.
The frame of the T-top is definitely made from metal. If I mount the
radio antenna on the T-top, I will be mounting the antenna right on an
metallic object.

Not a problem since the metal is under the antenna. What you need to
avoid is metal at the same height or above the antenna. In reality
these rules are broken all the time with only minimal impact on
performance. They are good guidelines however.