A window frame is useless. It's more another antenna,
than a ground. Why do you need a ground? Myself, I
wouldn't use one...Heck, I'm on the ground floor here,
and I don't use one...And I transmit too...You don't
mention the antenna. If you use a complete antenna,
that does not require a ground to complete the antenna,
there is no need for a ground. This is the route I would
take. If your antenna is indoors with you, you probably
won't be able to escape all noise. MK