Keeping Cats Away From Ground Feeder

Hi. I have a good tall bird feeding station on my patio which is used quite a bit by various birds, Im pleased to say. I also recently bought a ground feeder tray for blackbirds, robins, chaffinches, etc to use, but I've found that several cats in the area like to come and eat all the food I put on it! Is there any way I can keep the cats away from the tray? I really want to be able to provide food for ground feeding birds but there's never anything left for them to eat, thanks to the cats! I'm also always worried that I'm putting the birds at risk of being attacked by putting food on the ground for them, although thankfully this hasn't happened yet!

Any advice on feeding ground birds whilst still protecting them from cats would be appreciated!  :)