Buy 20 or 30 feet of small guage wire and a small fishing
weight to hang out the window and wrap the end around your whip antenna.

It might be better to use a small plastic ball, or piece of fabric, something
heavy enough to give 'some' weight (you don't need much, the antenna doesn't
have to be straight as an arrow to receive) but something which also, in case
the antenna breaks or falls, won't cause any real harm to any people, cars or
windows below. Years ago a friend and I discovered that even a small weight
can, when buffeted by winds, pendulum itself into enough velocity to crack a
lower story window, then the antenna wire snapped, and the little 2 oz. weight
tumbled another two stories to the concrete, and if anyone had been under it,
it could have given them a nasty knock. Just something to consider.
But heck yes, getting ANY kind of extra wire outside or strung around the
ceiling will improve reception over what he's using now, and one doesn't need
to spend real money to get as good an improvement as that $100 experiment would
give.
Linus