An electrician, from the regional NSW town of Young, has been jailed for at least six years and nine months for researching and designing long-range guided missiles and laser warning devicesfor Islamic State via the internet.
Haisem Zahab, who was arrested in March 2017, pleaded guilty in October last year to knowingly providing support or resources to a terrorist organisation.
Zahab, 44, researched and used 3D technology to develop the mechanical design of a laser warning receiver that provides notice of incoming laser-guided weapons.
He created a 288-page report on the receiver and sent it via secure software to a British national who later admitted to being a member of IS.
He also simulated flights of rockets, some wrapped in Islamic State's black flag with white writing.
Zahab, an Australian citizen, also admitted to failing to comply with an order to assist access by police to encrypted data on his phone and other devices.
Zahab said he had resiled from his extremist views. He said he was in a cult or bubble of IS supporters including on Twitter and was "hoodwinked" about IS news until taken into custody.
NSW Supreme Court Justice Geoffrey Bellew on Friday jailed Zahab for nine years with a non-parole period of six years and nine months.
Family members gasped and cried out in the public gallery as the sentence was handed down.
Justice Bellew described Zahab's nightly research as secretive and sophisticated, carried out "with unwavering focus, at all times intent upon assisting IS in its involvement in armed and violent hostilities overseas".
Justice Bellew rejected Zahab's claim he genuinely believed IS was "a force of good" at the time of his offending, describing the proposition as "fanciful in the extreme".
The judge was also sceptical of his subsequent contrition.
Outside court, Tarek Zahab told reporters he did not think his brother was radicalised.
He said his brother's testimony at his sentence hearing in May to "categorically reject the evil of IS" had put him in danger in Goulburn's Supermax jail.
"At the end of the day, the guy has come out on record - which is very, very difficult. It's a vicious group," he said.
"He's pretty much put himself and his life on the line."
Zahab's sentence was backdated to his arrest in early 2017, meaning he will be eligible for parole from December 2023.
AAP, Rachel Olding