i shoot foxes for farmers, gamekeepers etc.
with the exception off electric fences, there is no deterrent to foxes other than trapping and then shooting or shooting them.
foxes are creatures of habit and will usually visit at a similar time each night
one trick if you want to know what time he is visiting is to buy a small battery travel alarm clock, attach a chicken carcass or similar as bait, to a peice of string, tie this to a peice of fishing line then wrap this line around the battery, set the time put the battery in the clock and place outside...... the fox will come, take the chicken, pull out the battery and the clock will stop, do this a few times and you will know what time he is visiting
this will help if you have someone who can shoot the fox as it means you wont have to stop up all night waiting for him, just get into position half hour or so before he arrives.