Tuning simple resonance Transmitter Receiver circuits - Page 1
Forum section: electronics / general

author: adras
author_rank: Regular Contributor
timestamp: September 27, 2024, 11:48:20 pm
content: I was just wondering the following. Please excuse my crude language, I'll try to be as accurate as I can.Now let's say I have an input signal. I tune this to an LC circuit. Giving me my signal generator, a capacitor and an inductor. I simplify a lot and say my inductor is actually a dipole antenna. Now as it's a tuned resonance circuit, I have a resonance transmitter. Nothing fancy, that's as far as I know state of the art RF stuff.Next at the receiver end, I have the same antenna, and the same LC circuit. But there's nothing connected to it. So basically the receiver capacitor get's charged by the inductor due to the incoming signal, and then discharges into the same inductor, basically sending the wave back. Kinda like reflecting, but it's more a copy, a phase shifted one.Now at some point in time, this wave from the receiver will hit the transmitter again.And now I'm just wondering, what can we get, if we tuned the entire setup (the distance between transmitter and receiver, the frequency of the LC curcuit in relation to the distance and phase shift) to have it resonate not only in the LC curcuits but also in the Receiver and Transmitter?Mathematically it seems to be easy, yet it's function within function, pretty interdepending. I just cannot solve that, not even with the AI.

author: Benta
author_rank: Super Contributor
timestamp: September 28, 2024, 12:44:53 am
content: What you'll have is two coupled tuned circuits.A bit like an IF transformer in a radio, but with significantly less coupling.The signal relation betwen the two is inverse cubic, so the feedback (influence if you like) on the transmitter is inverse (cubic squared).unless the two are extremely close together, the influence of the receiver on the trsansmitter will be infinitessimal. Phase cohenrence or not.Your reliance on AI here is misplaced. AI only amplifies silliness.

author: TimFox
author_rank: Super Contributor
timestamp: September 28, 2024, 01:50:49 am
content: You can simulate this in Spice, with two identical L-C-R circuits and a user-set coupling co-efficient between the two inductors.With mutual inductance, the coupling works both ways.The interesting parameter is the product ofkxQ, wherekis the coupling co-efficient andQis the quality-factor of each resonance (geometric mean if they are not equal).WhenkxQ<< 1, you get a resonant peak that is narrower than the single resonance.WhenkxQapproaches and exceeds 1, the peaks split and move away from each other (fun to watch on a spectrum analyzer).There is an analogous situation in physics, for molecule-molecule scattering, but not germane to your question.

author: adras
author_rank: Regular Contributor
timestamp: September 28, 2024, 05:34:25 pm
content: I'm having a hard time to understand that tech jargon.When you say the signal relation between the two is inverse cubic, what does this exactly mean? While talking to the AI, it seems like there are phase shifts, that need to be dealt with. Is this what you're trying to say? A 180° phase shift, collapsing the wave?As far as I'm concerned I see it like this. I have my resonating sender circuit, sending a wave at say phase 0 initially. After that wave is received and passed through the LC pair, it's kinda delayed, phase shifting it. I didn't trust the AI that it's 90°, but it seems to be reasonable. Thereby the signal sent back would be at 90°, basically reducing it's powerlevel, instead of boosting it, which would be at 360°.Is this about right? We might get lost in language here.

author: TimFox
author_rank: Super Contributor
timestamp: September 28, 2024, 06:00:47 pm
content: "Inverse cubic" means the signal falls off as 1/r3, whereris the distance between the two circuits.What elementary electronics books do you own or have access to?

author: adras
author_rank: Regular Contributor
timestamp: September 28, 2024, 07:49:04 pm
content: Quote from: TimFox on September 28, 2024, 06:00:47 pmNone, I only have the internet I'm afraid

author: TimFox
author_rank: Super Contributor
timestamp: September 28, 2024, 07:57:24 pm
content: Public libraries?

author: Benta
author_rank: Super Contributor
timestamp: September 28, 2024, 08:45:07 pm
content: Quote from: TimFox on September 28, 2024, 07:57:24 pmUnlikely. But university libraries are a good bet, and they're free as well, but might not lend out the books (in-house reading only).The AI angle is a fools errand here, as all the good information is in (expensive) books, not on the interwebs.

author: TimFox
author_rank: Super Contributor
timestamp: September 28, 2024, 09:08:58 pm
content: I can't speak for Germany, but in the US elementary electronics books are usually found in public libraries.However, university libraries are not necessarily open to non-students/faculty.Some internet sites are as reliable as the men's room wall in public libraries.

author: Benta
author_rank: Super Contributor
timestamp: September 28, 2024, 09:39:44 pm
content: Quote from: TimFox on September 28, 2024, 09:08:58 pmHere as well. But this question is not really "elementary".I like your last comment. And don't call any of the phone numbers.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 29, 2024, 09:26:22 am
content: Quote from: adras on September 27, 2024, 11:48:20 pmWhat you are forgetting to take into account in your model, is the attenuation of the signal as it travels through the medium.i.e. a signal transmitted through air, will decrease in strength with increasing distance between transmitter & receiver.

author: adras
author_rank: Regular Contributor
timestamp: September 29, 2024, 02:17:49 pm
content: Quote from: Andy Chee on September 29, 2024, 09:26:22 amYes, true, I'm not trying to do any magic here. All I'm trying to do is to overlapp a wave created by the receiver perfectly with the one created by the sender, thereby amplifying it by resonance. Is that idea really so strange?

author: TimFox
author_rank: Super Contributor
timestamp: September 29, 2024, 02:34:11 pm
content: If you connect the two systems externally to a scope with two cables (that do not couple the circuits to each other), the phase relation on the scope will also depend on the electrical lengths (delay) of the two cables.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 29, 2024, 04:37:41 pm
content: Quote from: adras on September 29, 2024, 02:17:49 pmYes it is a strange idea. It shares similar principles to perpetual motion and free energy, both of which are impossible.Amplification can only occur when extra energy is put into the system. Due to resistance/attenuation, it is impossible for resonance to amplify.That said, your idea has name, "Standing Wave Ratio" and is commonly used to refer to waves reflecting along a wire cable medium, but may equally be applied to air medium. Again, amplification is not possible.As a mathematical model, you might consider transmitting along a waveguide to a receiver. Begin simulation with a normal sized waveguide, then increase the waveguide diameter until infinity, which is effectively open air. Again, amplification is not possible.

author: adras
author_rank: Regular Contributor
timestamp: September 30, 2024, 12:22:18 am
content: Quote from: Andy Chee on September 29, 2024, 04:37:41 pmAccording to the attached video - electromagnetic waves can be massively amplified by being reflected. (Because there is barely any power without the metal hull) as he demonstrates.If I have an antenna, I get a radiowave, if I put another one as close as possible, don't I amplify that wave?Because finally I would like to ask: Why is it impossible to amplify a signal from two sides? For instance, have antenna A at position 0, and antenna B at position 100, goal is to amplify the wave in between

author: Andy Chee
author_rank: Super Contributor
timestamp: September 30, 2024, 12:28:56 am
content: Quote from: adras on September 30, 2024, 12:22:18 amThe empty microwave oven with no food or water inside, is effectively a "mismatched load" and experiences high SWR (standing wave ratio). High SWR can generate high voltages, in the case of the microwave, potentially destroy the magnetron.HOWEVER, this high voltage does not amplify to infinity, again, due to attenuation/resistance.From your described experimental setup with only two antennas and no power supply, there is no energy input, hence no amplification.

author: adras
author_rank: Regular Contributor
timestamp: September 30, 2024, 01:35:53 am
content: Quote from: Andy Chee on September 30, 2024, 12:28:56 amIs it more important to you to contradict me, or to follow along?Take a magnetron, put your face next to it, nothing happens. Take the magnetron, attach it to a metal case, but your head inside that, BOOM. Why is that? because the waves send out by the magnetron get reflected, overlap themselves, resulting in an amplification. You call that standing waves, but a wave is never standing, it travels at the speed of light. It's peaks and troughs can be considered standing(as they don't move there location in space), which is the case when the frequency is not changing over time. If the frequency is changing, these peaks and troughs would move, but that's not important right now.I hope we can agree to this.I forgot to mention that my antennas are obviously not just standing around, trying to harvest free energy, but are transmitting a signal. I mean, instead of: "If I have an antenna, I get a radiowave, if I put another one as close as possible, don't I amplify that wave?" - "When I have a transmitter with an antenna sending a signal, and I use exactly the same transmitter, tuned exactly the same way, to transmit exactly the same, using exactly the same antenna, and I place both antennas as close together as possible, wouldn't the addition of the second setup amplify the signal sent?

author: TimFox
author_rank: Super Contributor
timestamp: September 30, 2024, 02:03:34 am
content: Define “amplify”: are you expecting to add power?

author: adras
author_rank: Regular Contributor
timestamp: September 30, 2024, 11:48:53 am
content: Quote from: TimFox on September 30, 2024, 02:03:34 amIn this case: Increase the amplitude of a wave

author: Benta
author_rank: Super Contributor
timestamp: September 30, 2024, 08:05:04 pm
content: Have to agree with Andy Chee.It seems we're moving in over-unity territory here.Bye.