Operation Terror, by Murray Leinster. (A pen name of William Fitzgerald Jenkins. He wrote a great deal of science fiction under this name.) First published in 1962. Available to read for free at Project Gutenberg, which is where I first encountered it many years ago when I was examining their copies of much of Leinster's work. (Apparently many of his copyrights were never renewed within the USA. The rule used to be that an initial copyright was only for 28 years, and you had to fill out some paperwork to renew it for another 28-year-term when the time came.)
The story starts out by telling us about how a few radars in the Western USA picked up a huge object coming down out of the sky, but moving surprisingly slowly for a meteor of that size. Also, its projected landing point kept changing, as if it were able to maneuver in mid-air according to someone's control, instead of simply being tugged down by gravity. Eventually it is reported to have splashed down in Boulder Lake, Colorado, accompanied by a shock wave detected by seismographs far away. The effect is described as being similar to the explosive force you would get if you set off one hundred tons of high explosive all at once.
(I just checked online. As I'd suspected, there doesn't seem to be a "Boulder Lake" in Colorado in the real world, although there is one in the nearby state of Idaho. So Leinster made it up. I suspect he didn't even know about the one in Idaho.)
The main character is several miles away from Boulder Lake at the time. He's camping out in the woods, alone. His surname is Lockley (I'm not sure we ever got a first name) and he's doing some sort of "survey" with electronic tools, as part of the preparations for turning the area into a National Park. Here's his first inkling that something weird is happening:
Lockley did not feel the impact. He was drinking a cup of coffee and
thinking about his own problems. But a delicately balanced rock a
hundred yards below his camp site toppled over and slid downhill. It
started a miniature avalanche of stones and rocks. The loose stuff did
not travel far, but the original balanced rock bounced and rolled for
some distance before it came to rest.
Echoes rolled between the hillsides, but they were not very loud and
they soon ended. Lockley guessed automatically at half a dozen
possible causes for the small rock-slide, but he did not think at all
of an unperceived temblor from a shock like high explosives going off
thirty miles away.
Eight minutes later he heard a deep-toned roaring noise to the
northeast. It was unbelievably low-pitched. It rolled and reverberated
beyond the horizon. The detonation of a hundred tons of high
explosives or an equivalent impact can be heard for thirty miles, but
at that distance it doesn't sound much like an explosion.
Toward the end of Chapter Two, Lockley has already found a friend named Jill whom he had known was in the area. He's crazy about her, but has never said so, because she's already engaged to a man called Vale. Then they have split up for a time, and so he's the only one who gets zapped by the mysterious intruders with what he will later learn has been dubbed a "terror beam." Here is the description of how it affects the human mind and body. He first noticed a nasty smell.
It was a horrible, somehow reptilian odor. It was the stench of
jungle, dead and rotting. It was much, much worse than the smell of a
skunk.
He moved to fling himself into flight. Then light blinded him. Closing
his eyelids did not shut it out. There were all colors, intolerably
vivid, and they flashed in revolving combinations and forms which
succeeded each other in fractions of seconds. He could see nothing but
this light. Then there came sound. It was raucous. It was cacophonic.
It was an utterly unorganized tumult in which musical notes and
discords and bellowings and shriekings were combined so as to be
unbearable. And then came pure horror as he found that he could not
move. Every inch of his body had turned rigid as it became filled with
anguish. He felt, all over, as if he were holding a charged wire.
He knew that he fell stiffly where he stood. He was blinded by light
and deafened by sound and his nostrils were filled with the nauseating
fetor of jungle and decay. These sensations lasted for what seemed
years.
Then all the sensations ended abruptly. But he still could not see;
his eyes were still dazzled by the lights that closing his eyelids had
not changed. He still could not hear. He'd been deafened by the sounds
that had dazed and numbed him. He moved, and he knew it, but he could
not feel anything. His hands and body felt numb.
Then he sensed that the positions of his arms and legs were changed.
He struggled, blind and deaf and without feeling anywhere. He knew
that he was confined. His arms were fastened somehow so that he could
not move them.
And then gradually—very gradually—his senses returned. He heard
squeakings. At first they were faint as the exhausted nerve ends in
his ears only began to regain their function. He began to regain the
sense of touch, though he felt only furriness everywhere.
He was raised up. It seemed to him that claws rather than fingers
grasped him. He stood erect, swaying. His sense of balance had been
lost without his realizing it. It came back, very slowly. But he saw
nothing. Clawlike hands—or handlike claws—pulled at him. He felt
himself turned and pushed. He staggered. He took steps out of the need
to stay erect. The pushings and pullings continued. He found himself
urged somewhere. He realized that his arms were useless because they
were wrapped with something like cord or rope.
By the time he's feeling himself again, able to see clearly and so forth, he's been placed in a large metal box with three other men. They theorize that they are perceived by the aliens as specimens of local wildlife to simply be collected now, and studied later, whenever it's convenient. Three live rabbits are dropped into the box, which is what triggers that hypothesis. Later, some birds and then a porcupine are added to the collection, which seems to further support the idea.
Lockley and the other men finally escape from the box. The aliens don't seem to have left any sentries to keep an eye on them. These four men agree to scatter so that, even if some of them get captured again, another might still be able to make it out of the area and report to the authorities. However, by the time Lockley finds his friend Jill again, he has developed some deep suspicions about what's really going on here. He never got a good look at his "alien" captors while he was still reeling from that "terror beam," and by the time his vision was clearing up, he'd been bound and blindfolded. The other men in the box untied him, and took his blindfold off, after he was dropped in with them. They all claimed to have had much the same experience -- never getting a good look at their captors.
This triggers a train of thought within Lockley, which he is sharing with Jill at the end of Chapter 3, after they have just listened to a newscast on the radio which acknowledges that an alien ship has landed in Colorado and the government is hoping to establish peaceful communications. (It also mentions that this "terror beam" seems to have a fairly short range.)
The news broadcast ended.
Jill said, obviously speaking of Vale, "He'll make them realize that
men aren't like porcupines and rabbits! When they realize that we
humans are intelligent people, everything will be all right!"
Lockley said reluctantly, "There's one thing to remember, though,
Jill. They didn't blindfold the rabbits or the porcupine. They only
blindfolded men."
She stared at him.
"One of the men in the pit with me," said Lockley, "thought they
didn't want us to see them because they were monsters. That's not
likely." He paused. "Maybe they blindfolded us to keep us from finding
out they aren't."
Lockley now spends much of the novel in a condition of what an outside observer might call "increasing paranoia." (But remember: It isn't paranoia if they really are out to get you!) He becomes increasingly certain that either the aliens have human servants helping out, or else that there are no aliens at all (his later conclusion) and the whole thing is some sort of hoax. He suspects that his country's enemies (probably one of the Communist powers of the Cold War, at least implicitly) have developed a secret weapon and intend to terrorize the USA with it while letting mysterious "aliens from outer space" take all the blame.
Impressively, he also somehow discovers a way to rig up an electronic contraption that will protect him from the effects of the terror beam. His discovery has other interesting capabilities as well, which I won't spoil for you.
As you said, it's all a hoax, but one with far more altruistic motives than Lockley (who seems to be a born pessimist) had assumed. Uncle Sam has devoted considerable resources to this, in order to fool the rest of the world (including most U.S. citizens) into thinking that the terror beam is the main advantage the aliens have over us when it comes to a showdown. What's really going on is that the terror beam technology had secretly been discovered by American researchers -- and also independently discovered by an enemy power -- but the Americans figure that if they quickly get the whole world scared of this weapon, then the world can also be persuaded to invest lots of money in some special equipment which will help protect people from the beam's effects. At that point, a threat to attack another country by using the beam on all their cities at once would become a very hollow threat indeed.
Here's a bit from the final pages, where a U.S. Army general is explaining to Lockley what's been going on, and why, and how, and so forth. (Jill's fiancé Vale participates in this discussion because he had been in on it all along, and had even lied to both Lockley and Jill about seeing those scary alien intruders with his own eyes -- which she was not amused to learn. It appears she will marry Lockley instead.)
"The fact is," said the general, "that our spies tell us that another
very great nation has developed this beam we've been demonstrating to
all the world. So did we. And we couldn't use it, but they would! If
they didn't use it against us, they'd use it for any sort of emergency
dirty trick. So we made up this invasion to persuade every country on
earth to arm itself against this particular weapon. Nothing less than
monsters in space would justify arming, in the eyes of some
politicians! Of course, they'll arm against us as well as—anybody
else."
He spoke matter-of-factly. A glance at Lockley's face would have told
him that persuasiveness would not work.
"This trick, with the defense we intended to reveal," the general
added, "should mean that a very nasty weapon won't ever be used,
either to start or end a war. Maybe the war won't occur because
we've said there are monsters who fly around in space ships."
Lockley had a confused impression that he was dreaming this. It was
not the way things should happen! This was not true! When he squeezed
or released the improvised switch in his hand, the rocket behind him
would disappear in a monstrous flame, and he and the three men who
faced him would, vanish, and there would be an explosion crater here
and a shattered mass of wrecked cars—
"It was an interesting job," said Vale. "The Army dumped a hundred
tons of high explosive into the lake. The two radars that reported a
ship in space were arranged to be operated by two special men, who got
their orders directly from the President. We picked a day with full
cloud cover; the radar operators inserted their faked tapes and made
their reports; and the Army set off the hundred-ton explosion in the
lake. From there on, it was just a matter of using the terror beam."
So I'm pretty sure that this is the same novel from the 1960s that you remember reading in 1970.
