Author Topic: any radio experts on here?  (Read 530 times)

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Offline welshman

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any radio experts on here?
« on: July 30, 2021, 04:15:54 am »
I have a question that I don't fully understand the concepts of, but I would like to know if something is possible.

I would like to change the frequency of a radio wave, shifting it from one to another. so as to be an antenna for one frequency and send it out in another frequency, with a high ratio of change. I would like to do this without any electronics or processing.

I'm thinking along the lines of something that can change the frequency maybe a cavity that resonates? an empty metal box of a certain shape, maybe channeling the with tapers. bouncing off edges. something about doppler I seem to remember. I don't really understand what I'm talking about. but I have an idea and would like some help with it.

is this even possible or am I talking nonsense?

input or clues appreciated.

Offline welshman

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Re: any radio experts on here?
« Reply #1 on: July 30, 2021, 04:20:11 am »
i seem to remember reading something about how a radio wave of one frequency can be used to alter the frequency of another, i don't really understand it though.

Offline welshman

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Re: any radio experts on here?
« Reply #2 on: July 30, 2021, 04:46:34 am »
if i put triangles of different sizes in a box and sent a radio wave through it, will that do it?  does anyone understand reflection, refraction, diffraction, absorption, polarization, and scattering properly, because i don't and i cant get any further.

Offline welshman

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Re: any radio experts on here?
« Reply #3 on: July 30, 2021, 05:29:38 am »
is it possible to divide a radio wave into multiple instances of a smaller frequency? by sending them down a metal tunnel splitting and then having them bounce about, each division slightly different length of path and arrive at a destination one after the other. ( apologies for multiple posts)

Offline welshman

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Re: any radio experts on here?
« Reply #4 on: July 30, 2021, 05:32:58 am »
and my last but most important question.

how could we end up with 50/60 hz

:)

Offline rossw

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Re: any radio experts on here?
« Reply #5 on: July 30, 2021, 06:35:17 am »
I would like to change the frequency of a radio wave, shifting it from one to another. so as to be an antenna for one frequency and send it out in another frequency, with a high ratio of change. I would like to do this without any electronics or processing.

is this even possible or am I talking nonsense?

You can (fairly easily) do a tripler, that you stick in say 430MHz and get the 3rd harmonic at 1290MHz.
(Square waves are the sum of all the odd harmonics).
So you need something to "mess up" the input signal, then some serious filtering to extract the harmonic.
Your output power is way down on the input, but it can be done.

If you're talking about anything near 50/60Hz, forget it. The filters would be monsters.
If you want outputs below the input, the only mechanism I know of is a divider or a mixer, but you're still going to need active components for a divider, and a mixer will need an excitation source, and filtering (you will get sum+difference, so you need to filter out the sum). None of this will be efficient at decent power levels.

Offline welshman

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Re: any radio experts on here?
« Reply #6 on: July 30, 2021, 06:47:38 am »
I would like to change the frequency of a radio wave, shifting it from one to another. so as to be an antenna for one frequency and send it out in another frequency, with a high ratio of change. I would like to do this without any electronics or processing.

is this even possible or am I talking nonsense?

You can (fairly easily) do a tripler, that you stick in say 430MHz and get the 3rd harmonic at 1290MHz.
(Square waves are the sum of all the odd harmonics).
So you need something to "mess up" the input signal, then some serious filtering to extract the harmonic.
Your output power is way down on the input, but it can be done.

If you're talking about anything near 50/60Hz, forget it. The filters would be monsters.
If you want outputs below the input, the only mechanism I know of is a divider or a mixer, but you're still going to need active components for a divider, and a mixer will need an excitation source, and filtering (you will get sum+difference, so you need to filter out the sum). None of this will be efficient at decent power levels.

thank you for your time and input. i see you mention square waves. what if we tried to capture triangle, sawtooth and sine. does that change anything? i don't understand, but i think you can see what i'm asking about. i would like to design a working prototype. even if it turns out to be inefficient and then work from there on it. i kind of, at this stage, just want to see 50hz ac coming out of a rf antenna outlet with no electronics. if that's even possible and if that's not possible, what would be the simplest amount of electronic components needed to make it so.

Offline welshman

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Re: any radio experts on here?
« Reply #7 on: July 30, 2021, 07:42:41 am »
I would like to change the frequency of a radio wave, shifting it from one to another. so as to be an antenna for one frequency and send it out in another frequency, with a high ratio of change. I would like to do this without any electronics or processing.

is this even possible or am I talking nonsense?

You can (fairly easily) do a tripler, that you stick in say 430MHz and get the 3rd harmonic at 1290MHz.
(Square waves are the sum of all the odd harmonics).
So you need something to "mess up" the input signal, then some serious filtering to extract the harmonic.
Your output power is way down on the input, but it can be done.

If you're talking about anything near 50/60Hz, forget it. The filters would be monsters.
If you want outputs below the input, the only mechanism I know of is a divider or a mixer, but you're still going to need active components for a divider, and a mixer will need an excitation source, and filtering (you will get sum+difference, so you need to filter out the sum). None of this will be efficient at decent power levels.


see these things http://dg7ybn.de/Splitters/coax_online_calc.htm I'm thinking along the lines of having only an input and an output and then instead of just  bending the tube once in the middle. bend it multiple times in adjacent directions creating a sine wave shape or triangle shape to the tube or turn the tube into a triangle wave shape metal maybe 8 or so waves. tunable with screws.. would that resonate or something ? magic happen?

Offline rossw

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Re: any radio experts on here?
« Reply #8 on: July 30, 2021, 04:41:15 pm »
The wavelength of a 50/60Hz waveform is about 4,000 miles.
Any kind of stripline or resonant conductor is going to be completely unmanagable.
Different shapes make no appreciable difference to anything, except in so far as it may slightly vary the inductance or parasitic capacitance.

You say you're wanting to capture power from an antenna - where do you suppose this energy is going to come from in the first place?
If it's very low frequency (eg, geomagnetic) the coupling is poor and you'll need phenomenally long antennas.
If it's high frequency (eg, commercial radio transmitters) the power density is very low unless you're right on top of the radio station. I cannot think of any mechanism by which you can divide the frequency from the carrier (where the power is) without the use of electronics that will in all probability take more power to operate than the recovered power out.

Yes, relatively low frequency radio waves can be rectified simply using diode junctions (or potentially from suitably constructed joints that naturally form a semi-conductor like corrosion and/or rust can) but that would only leave you with DC, not the 50/60Hz AC you seek.

Offline welshman

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Re: any radio experts on here?
« Reply #9 on: August 01, 2021, 07:43:34 am »
Thanks again for your input. I have managed to figure something out.

Offline welshman

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Re: any radio experts on here?
« Reply #10 on: August 01, 2021, 10:27:32 am »
 when doing silly things with a transformer, i noticed a different of output frequency. any ideas what is going on here?




Offline rossw

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Re: any radio experts on here?
« Reply #11 on: August 01, 2021, 04:16:22 pm »
when doing silly things with a transformer, i noticed a different of output frequency. any ideas what is going on here?

What are you measuring it with? A DMM or simple frequency meter will be reading either the highest or lowest frequency (depending on its sampling technique), or strongest (highest amplitude), or some mix of the above.

How are you generating the different frequencies? Are they phase-locked? Are they sinusoidal?

Run two or more frequencies into a transformer and you've just made a basic mixer. Depending on the inputs, you should get the sum and the difference. So put 150Hz and 200Hz in, and you will get 150 and 200 out, but in addition you'll get 350 (the sum) and 50 (the difference). You'll likely also then get at decreasing amplitudes, the sums and differences between the the new outputs too, so   350+/-50, and those products.
You have 3 lots of input, so you'll be seeing sum/diff of a+/-b, a+/-c and b+/-c, and all the resulting mixing products.

You are showing that you have an open-connection on one of your secondary windings, so you are purely measuring a voltage, there is no practical power coming out (because the source impedance is virtually infinite). Thus, apart from the mixing occurring in the transformer, you are also adding capacitive coupling between primary (primaries) and secondaries.

Add the non-linear transfer characteristics of the transformer as a function of frequency, and you could have anything on the output!

If you have (access to) a decent DSO, have a look at the output in the frequency domain (as opposed to time domain usually used). I think you'll suddenly see all these spikes in a graphical form that'll be obvious.