Michael Whitty, 47, had carried out internet searches for links between the mobile network and the global pandemic before targeting Vodafone equipment in Merseyside.
The father-of-three pleaded guilty to arson at Liverpool Crown Court, which heard he believed 5G was dangerous.
Judge Thomas Teague QC sentenced him to three years' imprisonment, saying there had been a “high degree of planning and premeditation”.
“There was use of firelighters and, in the sense that the aim was to put the mast out of action, there was intent to cause very serious damage to property,” he told the court on Monday.
Between £10,000 and £15,000 worth of damage was done to the equipment, which was out of operation for 11 days after the fire.
Simon Christie, prosecuting, said three people had been seen running away from the scene of the blaze in Kirkby, Merseyside on 4 April, but two had not been traced.
The arson was one of 13 recent attacks on phone masts in Merseyside.
When Whitty's home, on Perimeter Road in Kirkby, was searched later in April officers discovered firelighters similar to those found at the scene.
Analysis of his phone showed he had carried out searches on 5G technology, engaged in discussions on chat groups and had photos and videos of other phone masts around Liverpool.
Mr Christie said Whitty believed he targeted a 5G mast, although it was not clear if there was any evidence to confirm that it was in fact one.
Merseyside Police said that although no one was injured in the Kirkby incident, attacks on masts were “not victimless crimes and can have serious consequences”.
Detective Inspector Steve Ball said: “More than ever all members of the public are dependent on technology, including their mobile phones, to keep in touch with loved ones.
“People may also need their phone lines to contact the emergency services when they are in need and stupidity like this could put someone’s life at risk.
“I hope that this demonstrates to the public that crimes of this nature will be investigated and we will work with our partner agencies and take action against those who are responsible.”
Ben Ryder, from Merseyside Fire and Rescue Service, said: ”This is a clear message to those who would put firefighters and the public at risk by setting fire to phone masts – your actions have very real consequences for you.
“There is no scientific evidence of any link between 5G and coronavirus. Arson is a very serious crime and we will always work with our police colleagues to seek justice.”
Andrew Alty, defending, said Whitty had a genuinely held view about the potential dangers linked to 5G masts, adding: “That view may or may not be correct, time will tell. He acknowledges his response was wrong and disproportionate.”
He said the defendant, who runs parking facilities at Liverpool John Lennon Airport, had struggled to come to terms with the death of his nephew in 2014 and the subsequent acquittal of a defendant tried for his murder.
A parish priest and charity executive sent in references for Whitty, who carried out volunteer work including delivering food parcels.
Judge Teague said Whitty had 29 previous convictions, including for assault and for possession of a firearm, but none for similar offences.
He said he believed Whitty had shown genuine remorse and his charitable work showed a “positive side” to his character.
The case came amid a rash of attacks on phone masts and telecoms engineers linked to the spread of baseless conspiracy theories linking 5G to coronavirus and other harmful health effects.
Research by Ofcom has found that the claims are the most-common false information reported to be seen by the British public during the lockdown.
In May, protesters gathered in London and other UK cities in violation of coronavirus laws to protest against the lockdown, with many voicing 5G theories.
There are calls for social media companies to increase efforts to prevent the spread of the claims, after research found that only one in 10 posts reported for Covid-19 misinformation were being taken down.
Additional reporting by PA