A US man who hacked into his neighbors' Wi-Fi network and tried to frame them with child pornography and threatening emails to the US vice president has been sentenced to 18 years in jail.

US District Judge Donovan Frank sentenced Barry Ardolf, 46, on Tuesday after listening to the tearful testimony of Bethany Kostolnik, the Minneapolis Star Tribune reported.

"My husband and I had to explain to our young, innocent children way too early that there are evil people in the world -- and to never go in Barry Ardolf's yard," she said, according to the newspaper.

"Until Ardolf was incarcerated, not a day went by that I didn't think about another attack," her husband Matt Kostolnik said.

"Barry Ardolf has demonstrated by his conduct that he is a dangerous man," US attorneys prosecuting the case said in court documents.

"When he became angry at his neighbors, he vented his anger in a bizarre and calculated campaign of terror against them."

The trouble began in August 2008 when the Kostolniks, who had just moved into the neighborhood, reported Ardolf to police after he picked up their four-year-old son and kissed him on the mouth, according to US attorneys.

Ardolf then began exacting revenge by hacking into their Wi-Fi network and creating fake email addresses, which he used to send crude messages and child pornography to Matt Kostolnik's co-workers and boss, the prosecution said.

After Ardolf sent threatening emails in Kostolnik's name to Vice President Joe Biden and others, investigators discovered the hacking following a search of Ardolf's home in the summer of 2009.

Ardolf initially arranged a plea deal that would have had him serve two to five years in prison, but later backed out of it and fired his attorney.

In December Ardolf again pleaded guilty before changing his mind and trying to arrange another deal, but the prosecuting US attorney held him to the plea.