Back for his second spell at Westleigh Park, Paterson previously won the Isthmian League title with the Hawks.
The 29-year-old left Lee Bradbury's side following their promotion to the National League South.
Now, after stints with Oxford City and Welling United, Paterson says he's ready for a tough few months.
"It’s brilliant to be back, I’ve missed my time not being here over the past couple of seasons," he told the club's website.
"The lads have done well over the past couple of seasons and when the opportunity arose I was more than happy to be back here and be back at the club again."
"It’s a new challenge and I’m looking forward to it and I’m going to give everything I can for the team.
"There’s a little bit of nervous excitement seeing the gaffer and everyone again, I’m really looking forward to it and buzzing to be back here."
The club also announced the loan signing of defender Chris Robertson from Swindon Town.
Both could be in Lee Bradbury's squad for their game against Boreham Wood this Saturday.