RF cavities and related devices

[sophiecentaur]

I have a real problem when people say they want Science without Maths. Most people accept that Maths is part of their lives in general and wouldn't 'demand', for instance, to be given an explanation about the state of their credit card account which doesn't involve some Maths. They may, of course, just accept the bottom line of their bill every month (as many of us do) and that's all they can really expect from a non-mathematical approach to EM waves in cavities. Without Maths, you just have to accept some things and not expect to be able to predict or expand on things. No problem - just don't get cross when the explanations are unapproachable.

 

[artis]

I do understand basics , capacitance and inductance I understand those I also can imagine how the E field charges up the cavity plates and how then they discharge through the torus and then charge up the capacitor with opposite polarity and how the frequency of this LC circuit is determined by the inductance of the torus and capacitance of the cavity plates. I think I also understand how waveguides work in basic but I can't calculate these complicated formulas.

This being said I don't believe there isn't any simple explanation for why a certain size waveguide only works for certain frequency range waves. I can imagine optical fiber which I assume does the same function for waves only in different spectrum of the EM scale. The fiber as I understand it is a long long cable which acts as a long thin mirror and light is reflected from a mirror surface so the mirror like fiber helps minimize losses and helps light propagate, although optical mirrors cannot reflect non visible spectrum EM radiation like infrared near as good as visible so here I can understand why the fiber cable can act as a waveguide for certain frequencies only.

I feel that for RF and microwave waveguides since they are metallic the reason why they are good for certain frequencies is more about their size and the wavelength of the wave itself than material properties like in a fiber cable.
What I imagined is this. For example a 400Mhz wave has a fixed wavelength and the waveguides objective is to help that wave propagate, just like an optical fiber reflects light pulses a metallic wall reflects RF wave. I read that for the simplest situation the rectangular waveguide has to have a width that matches that of the wave. The example given was a transverse electric TE10 mode where the E field is transverse to the length of the waveguide. Only I did not understand whether the wavelength is one full period of the wave or half period because the pictures were showing a half wave.
Anyway this is probably as far as I will be able to understand this.

 

[artis]

By the way I couldn't find in google what is the average capacitance of an RF cavity?

 

[tech99]

Notice: I was told to make my own thread about the subject so here it is., please move it to a better subforum if there is a better place for it.At first I would like to ask three questions.
1) A torus shaped resonant cavity, like the ones found in particle accelerators and klystrons, is it a high frequency LC circuit, the parallel plate structure with the hole in the middle for beam passing is acting like the capacitor while the torus shaped outer part is a very small one loop inductor?
Is it then true that both in a klystron and also in a particle accelerator the cavity interacts with the beam of charged particles by the E field which is between the cavities plate like structure and the toroidal shape B field in the cavity torus is just a side effect of the charge running back and forth between the cavity plates connected by the torus bell or however it is called.?
2) Is my understanding of the klystron correct, both the input and output cavities work the same way only the input cavity is supplied by a RF signal of low amplitude (weak) which then creates a low strength RF oscillation in the input cavity, the electron gun emitted electrons pass by the cavities center hole where they are disturbed by the RF E field that forms between the cavities center plates and so in one half period of the signal passing electrons get accelerated while in the other half period electrons get de-accelerated or pushed back against, further down the "drift tube" this creates regions along the beam path of higher and lower electron concentrations with corresponding higher and lower E field along the beam path, as these regions pass the second or multiple second cavities they induce a RF E field between the cavity plates which then oscillates the cavity. The extra gained energy (wave amplitude) is due to the electron beam gaining energy as it gets accelerated towards the anode.
3) It seems that at RF and microwave frequencies the wavelength is small enough so that along a waveguide the EM wave can reach multiple positive and negative peaks which induce opposing E and B field lines along the wavepath inside the waveguide, is it possible to have a RF or microwave solenoid or something remotely similar where for example the B field lines all point in the same direction through a surface of some given area like it normally is with a low frequency or DC electromagnet?

I read about transverse electric and magnetic modes where one field is transverse to the wave propagation direction while the other is parallel to the direction of propagation,is it possible to have a situation where one of the fields either E or B is parallel to the path of the waveguide and at peak points would resemble the field lines coming out of a solenoid magnet?Thank you very much.

The thread has been going for ages, and is a bit hard to follow, so I would like to comment on your original question.
1) Correct. Similar action is seen in the cavities of a magnetron, which are big holes drilled in a copper block with a slit facing the electrons. When they made the first cavity magnetron, Randall and Boot based the design of the resonator on the original wire loop used by Hertz. The wire is nominally half a wavelength long but the capacitance between the balls at the end make it less than this - the same with the magnetron and klystron resonators. The hole in the centre is itself too small to accommodate a wave.
2) Correct, with the addition from Sophie Centaur that the additional energy comes from the high tension (B+) supply.
3) If you take a metal pipe, it is possible to fit a wave into it provided an internal dimension is greater than half a wavelength. You can see this if you try to send a wave between two metal plates which are spaced too closely - there is no transmission if closer than half a wavelength.
The modes in a waveguide are just the field patterns arising from a propagating wave. Whereas in free space the E and B fields are at right angles to the direction of propagation, in a waveguide there is also a component along that direction. There is a good practical description in "Antennas" by J D Kraus.

 

[sophiecentaur]

I do understand basics , capacitance and inductance I understand those I also can imagine how the E field charges up the cavity plates and how then they discharge through the torus and then charge up the capacitor with opposite polarity and how the frequency of this LC circuit is determined by the inductance of the torus and capacitance of the cavity plates. I think I also understand how waveguides work in basic but I can't calculate these complicated formulas.

This demonstrates your problem. I tried earlier to point out that a cavity is NOT just two lumped components but you are not taking that on board. Perhaps a mechanical equivalent could help here. Imaging you have a wave tank with water sloshing from one to end. You can excite it at its resonant frequency, with nodes each end and an antinode in the middle. The same frequency can be obtained with a single mass and a massless spring. You are implying that the tank can be described as just two components but where is the spring and where is the mass in the water tank? You ask what is the Capacitance of the cavity and what is the inductance and that is not answerable.
Also, waveguides cannot be treated as simple LC structures. Depending on where you 'drive' them from (where you introduce the power with a loop or a slot etc.), a waveguide can appear to have a Low Impedance or a High Impedance.
You say you don't understand complicated formulae so you just have to take what I say as basically true. It's a door to which you have no access until you are prepared for a bit of Maths. There is no simple arm waving model for cavities and waveguides. I can suggest that you do a Google Images search for fields and waves in waveguides and hunt around the numerous pictures you will find.
One important thing about waveguides (@tech99 mentions it, above) is that the only work when they are big enough to support a progressive wave. It's a very sophisticated concept and is only a limit for transverse waves; a wave tank can propagate longitudinal waves of any wavelength and the two waves are very different in this respect.

 

[artis]

Your last post was unclear to me at first but then on a second though are you trying to tell me by the water analogy that at RF and microwave frequencies the cavity is nothing but a "tank" whose geometry and parameters allows for the wave to "slosh" aka resonate and that just as one cannot identify a spring and a mass in a resonating water tank one cannot identify the individual parts in a cavity unlike a traditional LC circuit formed from inductors and capacitors ?

Would I be better off as viewing the cavity as a special sort of waveguide whose geometry is such that the wave is like a standing wave just resonating back and forth between its two possible states (E field and B field) and due to the geometry the E field forms between the capacitor like plates while the B field forms when the charge runs back and forth through the torus in between the E field cycles?

So a modified waveguide would achieve the same resonance even at the same frequency as a RF cavity just the difference is that in a typical waveguide it would not be possible to isolate out the E field as homogeneous in an area big enough to do any useful work on passing charges ?
I hope I'm shooting in the correct direction.

 

[sophiecentaur]

Would I be better off as viewing the cavity as a special sort of waveguide whose geometry is such that the wave is like a standing wave just resonating back and forth between its two possible states (E field and B field) and due to the geometry the E field forms between the capacitor like plates while the B field forms when the charge runs back and forth through the torus in between the E field cycles?

I would say you have stated it the wrong way round. A Waveguide is a particular form of Cavity which happens to be of the right dimensions to support a traveling wave with no reflections . A cavity can also be designed so that it has a high E field at some local place in it and that is good for accelerating charged particles. There are many examples in Science where it is better not to take Classification so far that it begins to drive understanding. It can be useful to classify things, of course but . . . .

 

[artis]

What is the average electron density in the electron bunch that forms before the output cavity of a medium power klystron due to velocity modulation at the input cavity for example?

Also what would happen to these electron bunches if one removed the output cavity of the klystron and simple made the tube end into a vacuum chamber where there also wouldn't be any confining magnetic field , I mean how far the electron bunches would travel with their gained kinetic energy before they spread out a lot? Sort of like imagine klystron being turned into an electron gun but instead of a typical electron gun where it shoots a stream of electrons this one would shoot bunches of them with some distance between each bunch. I simply wonder how far such bunches would be able to travel before significant divergence would happen and also what factors would determine this?

 

[sophiecentaur]

Also what would happen to these electron bunches if one removed the output cavity of the klystron

The electrons would just end up on the collector, as they do in the normal course of events. I wound;t imagine that passage through the output cavity would have much defocussing effect on the beam.
You could calculate the electron density by looking up the beam current for the klystron in question and seeing what the diameter of the beam tube is (for a minimum estimate), I would think. The distance between peaks of density would be the beam velocity X frequency of the RF. All these figures would depend on the particular klystron and application but ball park figures would not be hard to calculate. If you want better than ball park figures you would need to burrow down to a deeper level of design criteria.

 

[Klystron]

This document from SLAC (Stanford Linear Accelerator) provides klystron output data at high energies. Equations do not begin until ~page 5.
http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-9557.pdf

FTR capital letter Z represents impedance in the calculations, a measure that (roughly) combines aspects of capacitance (which you requested), inductance, and resistance. Small letter "e" or function exp(x) and inverse function ln() refer to logarithms. Note the grave danger operating klystrons without correct shields and protection.

 

[artis]

well sophie I was thinking not just removing the output cavity I was also thinking in moving the collector further away and then having an estimate at how far (in cm for example) the electron bunches would go (in free space outside the drift tube without a "steering" B field) before they start to spread out significantly. I was asking here because I lack the sophisticated math skills to arrive at a number myself.

by the way here is why I was wondering , I though about a scenario where you put two modified klystrons 180 degrees oppositely to each other , keep the electron source but the output cavity is not driven but rather it works as an accelerator cavity being fed from another powerful RF source (klystron) the two oppositely faced klystron cavities then synchronized in such a way as when one accelerates electron bunches toward the other the other can then "catch" them and push them back in the opposite direction and so these bunches of electrons oscillate back and forth between the two cavities. while the traditional klystron gun and input cavity makes up for lost electrons from the oscillating bunches

Maybe I'm into Sci-Fi but in IEC they have the problem of keeping the electrons (the potential well) confined in the middle due to the charge and low mass of the electron so I was wondering what would the the result of instead forming a traveling potential well on a vertical axis.

 

[sophiecentaur]

FTR capital letter Z represents impedance in the calculations

Impedance of what? It's confusing me. Is it the Impedance that the electron beam loads the cavity with? (Or perhaps the source impedance of the modulated beam?)
The "Z + 1.2" bit is interesting. It implies that the "impedance" must be fairly low, for 1.2 to be significant. Perhaps the impedance to the alternating currents in a beam of charged particles is, in fact, very low.

 

[sophiecentaur]

well sophie I was thinking not just removing the output cavity I was also thinking in moving the collector further away and then having an estimate at how far (in cm for example) the electron bunches would go (in free space outside the drift tube without a "steering" B field) before they start to spread out significantly. I was asking here because I lack the sophisticated math skills to arrive at a number myself.

I found this link which has some of the ideas that you have been looking at. There is an optimum length of amplifying section of a klystron. For a given beam purveyance (look it up), there is a maximum possible gain. The bunching process carries on along the length of a drift tube but the density modulation is soon non-sinusoidal and, eventually, fast electrons overtake slow electrons (over-bunching). The waveform starts by looking a bit like ocean waves, that are peaky and eventually can 'break'. Harmonics, by then, can be higher level than the fundamental - not what's wanted.
You say "I lack the sophisticated math skills`' so there is little point in trying to extrapolate into 'better' designs based on arm waving ideas. The first thing that will hit you is Bessel Functions, which describe the spectrum of the signal carried by the beam. Look through the link I posted. It gives some practical information about beam devices in general.

 

[artis]

I assume you meant perveance not purveyance? because searching purveyance google talks about crown princes etc

So per Wiki article on perveance in my own words, it is the ratio of how much current can be attained from a fixed PD across a fixed length and diameter due to electrons repelling each other and wanting to spread out (space charge effect) , does this sound right?
So in order not only to increase electron current but also stay at the same level of perveance, a larger Cathode-anode voltage is required?

 

[sophiecentaur]

I assume you meant perveance not purveyance?

That's auto spell checking for you. lol.
Apart from the anthropomorphic "Want to spread out", I would go along with that.

 

[Klystron]

Impedance of what? It's confusing me. Is it the Impedance that the electron beam loads the cavity with? (Or perhaps the source impedance of the modulated beam?)
The "Z + 1.2" bit is interesting. It implies that the "impedance" must be fairly low, for 1.2 to be significant. Perhaps the impedance to the alternating currents in a beam of charged particles is, in fact, very low.

@sophiecentaur, artis seems stuck on capacitance as a measure in his high-energy RF configuration while documents describe distributed impedance including the safety documents I included. Slowly, but surely, artis is describing a lab setup that would produce at least x-rays.

If artis or 'RF engineer friends' apply power to the rig s(he) describes with the shields removed so they can adjust the internal components of the dual "basketball player sized" drift tubes without calculation and, of course, after disabling safety interlocks most likely it will arc a/o burn out their RF sources. I can envision two fixes but cannot condone anyone conducting high-energy experiments without any math skills or understanding basic electronics such as impedance. Safety first.

Apologies if I have misjudged but any real seeker of electronic knowledge would at least study basics before designing high-E RF cavities, no?
@artis, please describe the klystrons you are working with and to what purpose. Thanks.

 

[artis]

I am not working with or designing a klystron, those that I posted where theoretical ideas as it is easier for me to learn through ideas to which I can then find solutions like the kid who puts the square in the square hole as then he learns how to fix certain things. I have repaired some old CRT's and vacuum tube amps and I think I have a basic understanding of how an ordinary vacuum tube works so that is as close as I'm standing to electron beams for now.
Sure klystrons non-linear way of operation and the RF cavity in itself is a whole different animal species which I only recently began to appreciate so take it slow with me.

So is such a setup theoretically possible where there are two oppositely positioned klystrons with externally pumped output cavities so instead of working like a RF source they would work like an electron accelerator and could the bunches be made such that they could oscillate back and forth between the cavities if timing is correct etc or would there be a large divergence of the electron bunches after they pass each cavity that only few of them would return while the rest would impact the opposite cavity walls and other surroundings? I already said why I'm asking this, just a curious idea.

 

[sophiecentaur]

So is such a setup theoretically possible where there are two oppositely positioned klystrons with externally pumped output cavities so instead of working like a RF source they would work like an electron accelerator and could the bunches be made such that they could oscillate back and forth between the cavities if timing is correct etc or would there be a large divergence of the electron bunches after they pass each cavity that only few of them would return while the rest would impact the opposite cavity walls and other surroundings?

That sounds to me like the daftest idea I have come across in many years. What are you planning to do with the DC components of the beam currents? How would the 'bunches' serve to augment each other? Just draw yourself a diagram of a simple two cavity klystron and figure out where its beam would go so as to merge with the bunches from a second klystron in such a way as to induce the same E field in a cavity. Where the beams cross, what are the electrons doing and, quite importantly, what job could they do for you? Would it be a 'just for fun' experiment?
You seem to want to treat this sort of equipment a bit like lego models.

 

[artis]

Well from what I read and which wasn't told to me here nor is loudly said in other places is that even though the electrons bunch up and form clusters by the end of the drift tube at the output cavity which is why there can be a high frequency AC field in it in the first place does not mean that there are no electrons in between the bunches. I saw the diagrams of the peaks and averages of the electron beam in a graph and then I understood that it seems there is a fair amount of steady static electron beam current and the peaks sort of ride on top of that.

Sure if my experiment was to have any merit the klystrons would have to be heavily modified there could be no steady electron current and the operation would have to be fully pulse like , the timing would have to be precise etc etc which is why it probably is a bad idea and not attainable in reality as you seem to suggest.But ok, suppose I have a RF device of high power and I can indeed create these discrete pulses which are precisely timed with an electron gun that replenishes for the lost electrons could I then have my electron bunch oscillate back and forth between two RF cavities in a free (vacuum) space inbetween them without the bunch spreading out so much as it is completely lost, sure it probably has to do with the strength of the accelerating field and distance of the "free space" between the cavities , or would this distance be very very small if no confining B field and drift tube is present?

 

[sophiecentaur]

But ok, suppose I have a RF device of high power and I can indeed create these discrete pulses

That's just a supposition. Do you not realize how difficult it is to produce pulses of high energy electrons? The purpose of a Klystron is RF Amplification and not to produce pulses of electrons. To do that, you wouldn't include an output cavity, would you? An output cavity will tend to spread the pulses out again, once the electrons have passed because it extracts RF Power carried by the beam. To produce pulses the thing to use is a control grid. The spectrum of the RF signal carried by narrow pulses is wide band and not what's needed from a klystron amplifier.
I really don't think there's much point in continuing this thread because you don't seem to have read about klystrons; you seem to have made up your own story about them.

 

[artis]

No I wasn't thinking about using the output cavity as an output cavity as it is normally used in a klystron instead use it as an accelerator cavity being fed by high power RF. Maybe to make it more clear say just an accelerator which instead of continuously accelerating electron/proton bunches forward oscillates them back and forth between two such cavities , that is all I wanted to know and this in no way ruins my knowledge or learning about klystrons, why be so pessimistic all the time?Also one more thing. In high frequency power supplies, the transformer for example is wound with litz wire , due to skin effect in order to make a larger surface area for the same cross area of wire I can understand this.
An RF cavity seems to be fabricated out of ordinary solid copper sheet metal that is bent etc but not made from multiple isolated copper parts, the same goes for waveguides , So please explain why here seemingly skin effect doesn't exist anymore?

 

[sophiecentaur]

use it as an accelerator

The output cavity would need a supply of RF power for this. You are talking about the techniques that are used in particle accelerators now.

So please explain why here seemingly skin effect doesn't exist anymore?

A wound component can usefully be made of litz wire when there is a long electrical path (as in an MF inductor in a receiver tuned circuit ). Litz wire is not used for physically large components- even the coils in mf transmitters. In a waveguide, which direction would you lay the strips of wire when the current could be flowing in many different directions as the wave passes? Instead of asking a question like that, why not read about it and get yourself informed before asking? Don't expect to get educated by an endless process of Q and A on PF. That will not generate good will here.

 

[Baluncore]

@artis.
Perhaps you should go back to some early RADAR engineer training references.
The “MIT Radiation Laboratory Series” covers equipment used in the first quarter century of RADAR.
You might start with Volume 7. Klystrons and Microwave Triodes.
The series archive can be found at the Jefferson Lab site; http://www.jlab.org/ir//MITSeries.html

 

[artis]

Thank you for the link, I downloaded most of the PDF files ,began reading about klystrons and microwave triodes

 

[artis]

the books in the link are rather old so some things have changed so just to sum up in modern times we use semiconductors like gunn diodes and transistors for low power RF and microwave amplification while we (due to technical reasons) resort to using klystrons, TWT etc for medium to high power RF and microwave amplification, now that being said I suppose that an average cell phone radio tower station doesn't use klystrons or TWT but semicoductors for feeding the antennas? I wonder what about tv, from what power level for the antenna usually semiconductors are abandoned?One more thing, due to the nature of, for example, klystron's velocity modulation which later translates into electron bunching "down the road" I feel like a klystron is best suited in amplifying sinusoidal waves but how good would it be with a different type of wave structure? I guess what I'm asking is doesn't the noise to signal ratio at output increase dramatically if other than sinusoidal signal is attempted to work with in a klystron, how about TWT , I read traveling wave tubes also work on the velocity modulation principle.?

 

[sophiecentaur]

I feel like a klystron is best suited in amplifying sinusoidal waves but how good would it be with a different type of wave

How about an analogue TV waveform or a DTV multiplex? Both signals occupy a total bandwidth of 7MHz at UHF frequencies of hundreds of MHz? Linearity limits the maximum signal level but there is no substitute for a 20kW UHF Klystron that I know of. TWTs can handle higher bandwidths but the powers tend to be less. But what do you actually want from this device and why?
Engineering is all about identifying a need and satisfying it as cheaply and as efficiently as possible. It is not about modifying a device and then looking for something to do with it.
"Signal to Noise" ratio at the output of a transmitting amplifier is Enormous. The signal to noise ratio of a single CW wave can also be enormous if you don't modulate it and are prepared to have a 0.01Hz bandwidth receiver but what would it be used for? You seem to be just using word / idea salad.

 

[Baluncore]

I feel like a klystron is best suited in amplifying sinusoidal waves but how good would it be with a different type of wave structure?

sophiecentaur is right. If the wave structure of microwave transmissions were not sine waves they would interfere with other transmissions. The limitation is on active element efficiency where bandwidth or Q is determined by the coupling networks employed around the active element.

Voyages of exploration are always more exciting and fascinating when less information is available, which tends to be the way of the freestyle inventor. Going around in unproductive circles can be fun for a while, a bit like doing cryptic crossword puzzles, but when an engineer needs to make something more reliable they go to the library and survey the literature. The advantage of old books such as the MIT Rad Lab series is that they contain surveys of historical fields that help us avoid wasting time and energy reinventing the wheel. They provide a solid foundation on which to understand and build.

There will always be advances that make older generations of technology redundant. The line between semiconductors and thermionic devices is dynamic and blurred in time, so it depends on application and your viewpoint. The gyrotron has extended power levels above 10 GHz, well beyond any semiconductors. https://en.wikipedia.org/wiki/Gyrotron

 

[artis]

thank you for the answers but I think to myself why are you assuming on my part and cornering me a little in your posts , sure I'm not saying my approach to learning is the best one it's just the one I have. Since I am polite and respectful I can't see why someone would be bothered with my questions.

I was simply asking about the types of waveforms these devices can best amplify because I thought about the possible limitations of the process that does the signal amplifying which is the bunching of electrons due to velocity modulation.
So sophie, you've said you worked with television etc back in the day , I tried googling the waveforms did not found much, so for NTSC signal or analog Tv in general it was both AM and FM modulated? So from the viewpoint of a klystron that has to "pump" an antenna I can understand the AM part where you take a fixed high frequency and by increasing or decreasing it's amplitude create a lower frequency waveform on "top" of it, that can be extracted by appropriate filters but how then the FM part comes in? At some specific AM peak in the right moment a burst of low amplitude but high frequency FM is put in? At least judging by the waveforms I saw the FM part seemed higher in frequency than the AM carrier?
The whole information into waveform coding is quite complicated so I'm not trying to learn television signals for now I am just curious of how a klystron can effectively with somewhat decent S-N ratio amplify all these minor ups and downs of an analog tv signal or does it do almost ok given that both the AM and FM parts are sinusoidal in nature ?
Although I might be giving electrons less credit than they deserve in terms of how fast they can react (velocity change wrt time) in order for these changes to be noticeable in the output cavity

 

[Baluncore]

@artis.
I think you are missing a key point. An RF transmission is a sinewave because that is all that will fit through the power amplifier (PA) or in the band. For a 500MHz carrier signal, the 2nd harmonic at 1GHz would be in another band. The important thing is that the power amplifier and the channel have sufficient bandwidth to pass the modulated carrier. For a 5MHz wide signal at 500MHz, the bandwidth need be only be 1% of the carrier frequency, so the Q of the amplifier and tank circuit will be about 100. None of the carrier harmonics are needed, so there is no point generating or radiating them. Any carrier harmonics generated in a radio transmitter PA must be attenuated before they are radiated.

An AM sinewave carrier will vary slowly in amplitude as it is modulated. An AM power amplifier needs to be linear and be able to generate an output amplitude that is proportional to input amplitude.

For FM it is the period of the sinewave that is important. The power amplifier only needs to produce a fixed amplitude sinewave with frequency varying slowly in time with the input signal. The PA does not need to be linear, it can be class C that kicks in time with the input frequency. Any carrier harmonics that result will be attenuated by the narrow bandwidth of the PA output circuit and antenna.

 

[sophiecentaur]

Voyages of exploration are always more exciting and fascinating when less information is available, which tends to be the way of the freestyle inventor.

And it accounts for the shelves full of non functioning projects that can be found in the sheds of many 'inventors'. It can become a habit to start a project and then abandon it before fruition. I have a feeling that your definition of 'freestyle' is probably not mine. Edit:[ You are not the kind of person who would launch out on a project without a good level of knowledge, I'm sure.]

, I tried googling the waveforms did not found much,

Analogue TV is not going to appear on the first page of many Google searches because it is out of date. If you look for the waveform of NTSC or PAL TV vision signal, you sill see the basic shape. The line synchronising pulses are very obvious and they correspond to maximum RF signal power because 'negative modulation' is used.
Your use of "Signal; to Noise" is still not very appropriate and I have no idea what you mean by "minor ups and downs". They are what constitutes the signal. A CW signal on its own is pretty useless for carrying information. CW is used in other applications (for instance, particle accelerators).
You really should settle down a bit and address one topic at a time. It's the only way you will actually learn anything. So far, in this thread, you seem to have addressed the major part of what I was involved in over decades of work and I wonder what you have actually taken on board. Scattergun Q and A is soooo inefficient.