there was an original novel?
Of course.The back story:
Some undefined disaster had occurred and destroyed civilization. Out of Asia came the Han Airlords with a number of advanced technologies and destroyed all other emerging civilizations they encountered. In the U.S. the survivors organized into gangs and made hidden settlements and underground factories. Each gang was independent and they didn't coordinate together.
Anthony Rodgers had been inspecting a mine in the 1920's and had been trapped. It was assumed that a freak natural combination of gases and radiation put him in suspended animation. Then when another land shift allowed in fresh air he awoke to a new world and encountered Wilma Deering who took him into the Deering Gang. After a series of events he coordinates the gangs of the U.S. and leads them in defeating the Han.
At the end of the book they find indications that the Han were hybrid Human/Aliens not a new Chinese civilization.
Han Airlord Technologies
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Rep Rays - pressor beams that they used to carry their "airships"
Dis - disintegrator beams which are also used as "walls" around their cities
Wall sized TVs that were used for virtual reality (remember this was published in the 1920's!) communications, telecommuting to work (factory workers included with teleoperated equipment) and entertainment (TV)
Human Technologies
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Inertron - synthetic metal resistant to Dis and it is repelled by gravity (and attracted by Rep Rays). They used this to shield some things from Dis but also to make travelling easier. If you weighed 200#s you would carry slightly less than that in inertron and "weigh" only a few ounces, you would still have full inertia of the total mass including inertron.
"Long guns" - rifles and pistols but with rocket shells (bazookas essentially though they hadn't been invented yet).
Note: this is all from memory so I may forgotten some things or made mistakes in detail.
About later novells
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Later there were more novels written by other authors based on outlines by Larry Niven and Jerry Pournelle. They extended things including making the disaster that ended 20th Century civilization be the events of their novel "Lucifer's Hammer". They also had Rodgers in suspended animation because he was taken in by an alien life support mechanism, repaired (to standards closer to the alien warriors levels than to human) and stored until the environment was habitable. He was not conscious when entering or leaving the concealled machinery and had no knowledge of it.
These novels cover various events decades after the original starting with an elderly Rodgers and Han resurgences from their own hidden cities.
I purposefully left things out of this to avoid "spoilers" for those whom may wish to read them.