Why is this unworkable patent claim approved?

Question

In reference to the patent: US3951134

The patent claims in simplest terms that by broadcasting two radio signals into the brain, that the brain's own radio signals can be modulated onto the combined signals and then picked up by receivers for processing, analysis, and other actions. If any radio signal can be modulated by another radio signal, then all radio signals are modulated by all radio signals (untrue). The patent makes no mention of this, and fails to provide a means to detect and filter out all other radio signals other than the brain's which would additionally be present, and neither does it specify that the process must be conducted within a faraday cage in order to isolate the process from all other ambient radio signals. In point of fact, radio signals do not modulate one another; the process as described is nonsense. Modulation is achieved by directly embedding a signal through electronic circuitry prior to broadcast, as in AM/FM radio (AM means Amplitude Modulation, FM means Frequency Modulation), and decoded in like means by radio receivers. Were this patent true and workable, AM/FM radio would be incapable of producing useful sound.

Answer 1

There is no burden on the inventors to prove their invention actually works. This patent is a good example of a useless patent. The examiner is just looking for novelty and apparent utility. In any case these types of patents aren't usually all that problematic since no one would want to infringe them. Much worse in my opinion are overly broad patents. Lastly, this patent has expired so if someone wanted to waste their time in this technology, they are free to do so.

Answer 2

Regardless whether patent law requires a working device, the technical objection above was focused on the two incoming waves themselves. Quite correct that they would never modulate each other [superposition]. But the patent never claims that the two input EM frequencies modulate one another. Instead, the inference is that the nonlinearities or change in refractive index, in the mass of the target are where the waves are crudely "mixed" and small heterodyne products are formed. My question would be 'How close must the "receiver" be to the target [the brain] to pick up these ultra-weak heterodyne signals coming from the brain?' Also, how much weaker would the "modulations" be, that the brain allegedly impresses on the heterodyne products? All sounds pretty unlikely until you do some reading about MRI technology, as was pointed out. Who 'da thunk that you could send RF pulses into living tissue within a magnetic field, turn the pulse off, and receive the gyroscopic recoil of the atoms as a very weak RF signal that could be amplified and reassembled into a detailed image of the brain? Science Fiction! And yet both of these technologies deal with signals much larger in magnitude than the passive magnetic fields that SQUID detectors have to deal with. And we know that SQUIDs work.