Every receiving antenna could be said to be powered by radio waves since it converts radio waves to signal (albeit typically quite faint) and antennas were known way before The Thing.
The difference between The Thing and other devices is that it modulated and reflected the signal at different frequency all without use of any electronics. Every RFID chip is a bit of electronics but The Thing actually is an analog device without anything that could be recognized as electronic circuit at first sight.
As far as I understand it used some kind of resonant cavity an some kind of change in capacitance dependant on the geometry of the device. The sound waves would cause the physical setup to vibrate and the vibration would change geometry of the device causing modulation of the reflected signal.
On the other hand - AM broadcast is still totally analog, so a crystal radio should still work! I should order a kit right now!
To extend the other comment about FM being digital (in the UK): so much tech we take for granted now is built upon layers upon layers of underlying technology. Devices have never been better but at the same time it's a real loss that we can't build stuff from scratch any longer. I learned so much as a kid from building - often bad - things.
They stress it had no active electronics. The imagery in the article clearly shows it had some metallic innards, presumably these are passive electronics for modulating the illuminating signal.
Probably lots of reasons that research like this is attainable is due to massive budgets/funding and the ability to research an try many things in these types of r&d departments and the urgency of some research/development goals. Intelligence or military project conditions rarely apply to private market project budgets and timelines, only comparison is maybe academic research where some of the same goals/freedoms apply and both have reduced labor or essentially free labor.
This reminds me what I read about Leonardo da Vinci "pitching" for funding and sponsorship, with various inventions for military use like crossbows, catapults, steam-powered cannons, armored tanks..
I wonder what these engineers would be doing with their time otherwise. What those tax dollars could have accomplished.
Sure we get a few pieces of technology, but it's at enormous cost.
Especially when we hear about small companies or founders able to create useful technology.
Not exactly perfect, but, a broken clock is right twice a day.
Innovation during war is expedited because while the government and public agencies are massively inefficient during peace time. In war the brightest resource are drawn/forced to align with the government, increasing its capability. Whatever redtape that used to exist are now ditched for more efficiency, while if you keep being a massively inefficient government, you risk losing the war and everything. All of these factors proceed to make innovation pace much faster on matters that are somewhat related to military.
The journey to the moon was an example of this. Did we do it efficiently? Probably not. We spent tons of cash and resources that otherwise may have been used more efficiently, but we achieved the objective.
During war, the biggest gain is SPEED in the prioritization and removal of red tape, and acceptance of risk (death, health risk, etc) to achieve the objective (as you mention).
Want to build a nuclear reactor in Chicago? Go for it. Have to build TWO competing uranium generating plants to hedge your risks at the costs of billions? Yes, of course. I would hesitate to say, however, that war develops these innovations more efficiently than at other times.
Not just government. During WWII, removing roadblocks to industrial productivity was a focus of government-industrial joint effort. Now, creating such "moats" is a focus of effort and policy.
Or take science education. During the cold war, there was much concern that it actually work. Else we fall behind. That concern permitted disrupting existing interests. Now... not so much.
As the saying went, "The US Army is at war. The US is at the mall".
I would not argue that this was efficient, well organized, or toward a single goal, but rather got a bunch of money dumped on it due to national priorities and something shook out.
There were also steps backward in preparedness due to the focus on counterinsurgency ops, e.g. loss of experience in areas such as air defence and armoured warfare which weren't relevant for most of the operation (also in Afghanistan).
As someone from a country that lost 20% of it's population to it, I'm going to go ahead and say that the last thing I ever want to see is another war that poses an existential threat to a superpower surrounded by two oceans.
This is where I like the approach the US has taken. Instead of spending all the military dollars in building more armaments or having more boots on ground, the US military recognized the importance of technology to military superiority and invested tons of money in it. And it has payed off very handsomely for the US economy, even in peace time.
Edit, vs Industry.
It's illegal for one to R&D one's own weapons and counter-weapons systems at certain functionality. If one wishes to develop cutting edge military technology, one must sadly commit his life to it at the government's approval.
Making labor saving inventions, communication, improvements to infrastructure, discovering new science.
I did not mean weapons.
If the thing can be made into a poorer resonator, it can be made undetectable to modern day bug detection