Microchips are good, but someone has to scan the dog to get the information. I know from personal experience that people find dogs, decide they like them and don't bother to scan the dog for a chip. I have all my dogs chipped, but that's not enough on it's own.
A regular old dog tag works the best for getting a roaming dog back fast. Being a cynic, I strongly recommend putting "REWARD" in the spot where most people put the dog's name. My sister lost her dog once and put up signs everywhere saying reward. A guy drove past the roaming dog, drove into town, saw the reward sign and turned around to go get the dog so he could get the reward. The hundred bucks she gave him was nothing compared to the loss of the dog. I don't count on people's good will, I count on their self-interest.
On your tag, list two people's phone numbers. Another person's dog got lost and she had her number as well as her mom's on the tag. When someone found the dog, she didn't answer the call (she wasn't home and didn't even know the dog was missing). The second number alerted her mom to the situation and she was able to get the dog home safely right away.
Finally, get a better gate situation and train your dog not to run through it. "Boundary training" isn't that difficult and it can really work well. You may need a few lessons with a dog trainer to get this one going. Basically, you teach the dog that running through the gate is forbidden. If possible, don't ever let him go through that gate. You could carry him out or take him another way on walks and such. If he's big and you have to let him go through the gate sometime, be clear that it is only allowed when you take him by the collar and lead him through.
After you have completed the boundary training, you might finish it off with an invisible fence over the gate for the times when you aren't there. I'd set it up so he got corrected if he even got within a few feet of the gate. But, this will only work if you also train him how to respond to the invisible fence warning tone and correction. Many dogs learn to just rush through really fast and "take the punch" in exchange for run time.
Finally, are you exercising that dog enough? If his roaming is sexual in nature, then neutering should really help. But if he's just bored and lonely, you need to make an effort to take him out more with you, on a leash. Give that boy his time every day!