Gary Bolton, 47, sold the phoney devices to international clients for up to £10,000 each, boasting of their ability to detect explosives, narcotics, ivory, tobacco and money.
But the equipment, which cost less than £5 to produce, offered no greater detection rate than random chance. Despite this, Bolton peddled the devices - with soldiers among those said to have been handed the equipment.
Sentencing Bolton at the Old Bailey yesterday, Judge Richard Hone QC accused the father of three of damaging Britain's international trading reputation.
He said: "You were determined to bolster the illusion that the devices worked and you knew there was a spurious science to produce that end. They were useless.
"Soldiers, police officers, customs officers and many others put their trust in a device which worked no better than random chance."
The devices were no more than boxes with handles and antennae that Bolton, of Redshank Road in Chatham, Kent, made at home.
Bolton was found guilty of two counts of fraud last month. His company Global Techical Ltd had a turnover of £3 million, with 5000 devices made. Bulk orders meant the GT200 was sold for between £2500 and £10,000, although they retailed at up to £15,000 if bought individually. Around 1200 devices were sold to Mexico, while orders were shipped to Asia and the Middle East.
Outside court, Detective Inspector Roger Cook said: "He was putting people's lives at serious risk."