Airport signal strength / MacStumbler

[Ken Rossman]

My main work machine is a 14" iBook, which also has Airport installed.
I travel around with it to different places and attach to various 802.11
networks, with varying degrees of success.  I have some questions about
this, and would be interested in other people's experience.

I can be attached to a given 802.11B network, and come in with a very
strong signal.  However, during the course of my working on that 
network,
and without physically moving at all, I see the signal varying widely 
from
full or near-full strength, all the way down to zero, then back again
(MacStumbler has been an extremely useful tool for observing this
"coming and going" nature of the nets).

In any case, I was wondering if other people are having the same kind of
experience with airport networks "coming and going" (varying widely in
signal strength) during the normal course of usage.  I am wondering if
my iBook is perhaps a little bit broken (it IS pretty banged up and is
in a questionable state otherwise).

So is this a problem with my iBook, or is this a symptom that just
happens with 802.11B nets in general?

Thanks,

K