The winger enjoyed regular first-team football with the Us in League One, netting four times in 16 appearances in Essex before his temporary stint with John Ward's side expired last weekend.
Now the 21-year-old is back at the Madejski Stadium, ready to fight for a place in the Royals' matchday 16, and Antonio reflected on a productive time away from Berkshire.
He told the Reading Post: "It was definitely worth it. I just felt that I wasn't as confident as I was when I came back from Southampton and I thought I needed to be a lot sharper.
"The couple of games when I came on for Reading I thought I wasn't as good as I could have been.
"I feel I've achieved what I wanted and now I feel I can try and get back into the side here."