Passive radar?

I think it’s really quiet with news about passive radar. The last picutre I saw was a picture about a rather big building with panels attached to it, that was used to collect background radio noise to filter out aircraft positions. I wonder how far the technoligy has improved to miniaturize the radar. Has anyone information about it? Is it possible to use it in a fighter? And is it maybe possible to fix the enamies position to lock on to it and fire an missile?