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 continued to peddle the devices - with soldiers among those said to have been handed the equipment.
Sentencing Bolton at the Old Bailey today, 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 had a random detection rate. 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, known as GT200s, were no more than boxes with handles and antennae that Bolton, of Redshank Road in Chatham, Kent, made at home.
It allowed Bolton's company, Global Techical Ltd, to amass a turnover of almost £3 million, with up to 5,000 devices made.
Bulk orders meant the GT200 was sold for between £2,500 and £10,000, although they retailed at up to £15,000 if bought individually, the court was told.
Around 1,200 devices were sold to Mexico, while orders were also shipped to parts of Asia and the Middle East.
The devices are still being used in Thailand, the court heard.
Bolton, wearing a grey polo shirt, black trousers and canvas shoes, closed his eyes as his sentence was read out.
The judge said: "You're a fraudulent person. You have no remorse."
A confiscation hearing is due to be held next April.
Speaking outside court, Detective Inspector Roger Cook said: "Gary Bolton made a fortune selling devices that were supposed to be able to detect explosives and other harmful substances but in reality were nothing more than plastic handles with aerials as antennae.
"In doing so he was putting people's lives and livelihoods at serious risk, but his sole consideration was how much money he could make."
Richard Whittam QC, prosecuting, said Bolton admitted in interview to having no background in science, research, training or security. He was arrested in June 2010 following an investigation by City of London Police's overseas corruption unit.
His sentence came after fellow conman James McCormick was jailed for 10 years earlier this year for three counts of fraud from selling fake bomb detectors.
McCormick, 57, of Langport in Somerset, was said to have made £50 million from his scam.
Representing Bolton, Jonathan Higgs QC told the court that his client's offending - between 2007 and 2012 - was not on the same level as McCormick's.
He said: "There is no suggestion that these devices were to be sold to and deployed as frontline devices to counter terrorist threat.
"The countries to which tenders were made were using these devices for a range of different detections.
"This is a device which was sold honestly to start with."
But the judge said he did not accept that suggestion, also questioning the validity of a psychiatric report which said Bolton was believed to have "a depressive illness".
He said: "You gave spurious credibility to this product. You have damaged the reputation of British trade abroad."
International Development Secretary Justine Greening said: "The work of the City of London Police's Overseas Anti-Corruption Unit, funded by the Department for International Development, is vital in helping to stamp out endemic fraud, corruption and scams and I congratulate them on this success.
"This sentence underlines their vital work in the fight against international corruption."