Antenna Location Question

I'd like to learn why sometimes moving a wireless adaptor's antenna by
just a few inches can cause a significant performance difference.

Ex: Today SWMBO came down to my office (We both work in our own
business' office.) complaining that internet access on the computer in
her office was slower than molasses in January.

We use a Linksys WAP54G router to service the five computers in our
business. Her computer has a Linksys WUSB54G adaptor plugged into it.

I gave her my usual reply that MY computer was connecting just fine and
that she has so much junk and obsolete files stuffed in her computer
that it probably needs an enema to get its performance back to where it
used to be.

That strateguy didn't work, so I hauled my ass down to her office and
had a look.

She was correct, internet access on her computer was awfully slow, even
though none of the other computers in the office were in use then.

Her computer is the closest one to the router, only about 25 feet away
with nothing more than a couple of drywall partitions in the way. The
adaptor software reported excellent signal strength and I checked to
make sure that the wireless channel we were using was still unoccupied
by any of our neighbor's wireless systems.

To make a long story shorter and less boring, I solved problem by simply
moving the wireless adaptor about four inches sideways on the bookshelf
it sat on, and her computer instantly regained its usual internet access
speed.

I understand how multipath signals can cause RF nulling, but I'd expect
that the adaptor's software would report "poor signal strength" under
those conditions. It's the "good signal" report combined with lousy
performance that has my inquiring mind wondering what's really going on.

Thanks guys,

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.