We have had our cat for about three years and he still does that - it drives me mad!
Still, looking on the bright side, at least you won't get any neighbours complaining about your cat pooing in their garden
Move the tray closer to the door each day, then start mixing in handfuls of soil with the litter. After about a week you should have the tray outside the door with at least 50/50 soil/litter (assuming you eventually want the cat to stop using the tray all together)
Has worked with all of our cats. Only time litter tray is used now is winter when the ground is too solid for them to kick at.
My cat used to do this, I moved litter tray nearer to back door and then outside door. Also have you seen those litter trays with lids? Its like a personal, private cat loo! We had one of these, and left it out in all weathers.
Also, FWIW, my ex-neighbour (whose cat used to be able to go in and out with a cat flap but can't now cos she only has patio doors) has got some stuff in her litter tray which instead of ordinary litter is sort of long pellets made of woodpulp or something...no idea what it's called or where she gets it, I could ask her if you like?