How do I stop cats peeing on my porch

[RadiatorWatch]

I live in a street where a few cats are resident, we don't have any pets.
Some cat/cats keep pissing all over my outside porch.
Does anyone have any (animal friendly) ideas on how to keep them away?

Cut a lemon or 2 in half and leave in your porch? Cats hate lemon.

How do you know it's cats? Foxes do this at my house. The smell is similar but worse.

I put a little bio washing powder&water in a spray bottle when we had a stray tom in the area.

A roaming local cat weed on my porch and front door mat. I had to throw the mat out but after washing the porch with a solution of white vinegar we haven't had any more problems. Also i bought a new doormat which i guess doesn't smell of cats (yet!)

The only thing I've found that gets rid of cat urine smell (and I had tried everything - bio washing liquid, white vinegar, bicarb etc etc) was that MN favourite - Zoflora. The citrus one is particular good. But really it's a revelation.

I'll second the chopped up lemon, litter training kittens was a disaster until I learnt this!