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#3220 by X_RaY on 17 Jun, 2016 18:32
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Maybe I am dazzled by the pictureRegarding Dr. White's theory, for me a question remains since thread 3: How may it possible that charged particles (e+;e-) escape from a metallic cavity?
Yes, good question, if one is prepared to accept the notion of a degradable vacuum...
Perhaps he is saying that the interaction between the electromagnetic fields and the degradable vacuum virtual pairs occurs inside the EM Drive cavity, and that these virtual particles are ephimeral, extremely short-lived, so that they disappear back into the vacuum before the metallic wall has any chance to interact with them after that happened. Essentially saying that the "propulsion" occurs inside the EM Drive.
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#3221 by Rodal on 17 Jun, 2016 18:55
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Maybe those are virtual pairs that popped into existence outside the cavity. I notice that there are more dots inside the cavity than outside the cavity though. The main vector arrow starting inside the cavity.
Maybe I am dazzled by the pictureRegarding Dr. White's theory, for me a question remains since thread 3: How may it possible that charged particles (e+;e-) escape from a metallic cavity?
Yes, good question, if one is prepared to accept the notion of a degradable vacuum...
Perhaps he is saying that the interaction between the electromagnetic fields and the degradable vacuum virtual pairs occurs inside the EM Drive cavity, and that these virtual particles are ephimeral, extremely short-lived, so that they disappear back into the vacuum before the metallic wall has any chance to interact with them after that happened. Essentially saying that the "propulsion" occurs inside the EM Drive.
I see your point though, are the vector arrows outside the cavity, parallel to the conical walls, supposed to be taken literally as having been produced outside the cavity ? -
#3222 by X_RaY on 17 Jun, 2016 19:11
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It seems we have to wait for the NASA(paper?) at this point.. This pic is the only one I have ever seen in this regard.
Maybe those are virtual pairs that popped into existence outside the cavity. I notice that there are more dots inside the cavity than outside the cavity though. The main vector arrow starting inside the cavity.
Maybe I am dazzled by the pictureRegarding Dr. White's theory, for me a question remains since thread 3: How may it possible that charged particles (e+;e-) escape from a metallic cavity?
Yes, good question, if one is prepared to accept the notion of a degradable vacuum...
Perhaps he is saying that the interaction between the electromagnetic fields and the degradable vacuum virtual pairs occurs inside the EM Drive cavity, and that these virtual particles are ephimeral, extremely short-lived, so that they disappear back into the vacuum before the metallic wall has any chance to interact with them after that happened. Essentially saying that the "propulsion" occurs inside the EM Drive.
I see your point though, are the vector arrows outside the cavity, parallel to the conical walls, supposed to be taken literally as having been produced outside the cavity ? -
#3223 by Star One on 17 Jun, 2016 19:37
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Doesn't all this new paper just make it a photon rocket?
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#3224 by dustinthewind on 17 Jun, 2016 20:36
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Doesn't all this new paper just make it a photon rocket?
If your referring to the paper where they state that two overlapping photons escape the cavity.Just found this paper entitled "On the Exhaust of Electromagnetic Drive" submitted by Grahn, Annila, and Kolehmainen in the journal AIP Advance:
If so my thoughts on that I think you might be right in that I don't see it being much more than a photon rocket (non recycled). Depending on the mass escaping would determine the ratio of energy transferred to the cavity. With out repeated reflections such as a recycled photon rocket I don't see how that much energy could be transferred unless the mass of the escaping photons was some how large.
http://dx.doi.org/10.1063/1.4953807
The authors postulate a potential theoretical underpinning for the EM drive effect which appears to be at least a partial departure from current theories and which also addresses problems wrt momentum conservation. I'm not qualified to comment on its veracity, but several here are. I'm curious to see what those well versed the relevant subject matter have to say...
Sent from my iPad using Tapatalk
One idea behind the recycling of photons here:[...
The other problem I see is that in a cavity, light is reflected because the current moves in the direction of the light stimulating it. When current moves in the direction light stimulates it this generates light that is opposite in phase to the light stimulating it. In effect if one imagines the stimulating light over lapping the light from the stimulated current they form overlapping light with destructive properties such that the light appears to disappear. On the other hand new light is created by the effect such that it appears to be a reflection of the stimulating light.
My point is this destructive interference of light should happen everywhere in the cavity (where ever there is a reflection). Maybe they are suggesting this destructive interference is only happening on one side?
A phased array works much the same in that this destructive interference happens on one side of the phased array while not on the other side. Thus a phased array can spit out light in a direction it wants by controlling the relative phase of current in its array.
Edit: also, in essence the concept of modifying the mass of light at one end of the cavity, I feel is connected to the Woodward or Mach effect. That is we have an object of mass that receives an impulse. We then change its effective mass and give it an impulse in the other direction. After repeated collisions the energy is more effectively transferred from the light to the cavity than would be possible with a single collision (a solar sail for example receives a small Doppler shift per impulse, but the Doppler shift is greater with many reflections when dealing with a recycled photon rocket, or possibly by modifying the photon mass at the narrow end of the cavity.)
In the paper where they discuss a greater impulse by photons in a medium (my empty quote link) and attribute it to a larger momentum I feel what they may be measuring is actually an increased transfer of energy via the change in relative mass of the photon. -
#3225 by X_RaY on 17 Jun, 2016 21:11
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In fact there is both destructive and constructive interference of interacting EM fields inside a cavity (especially with defined positions of the nodes and antinodes in the presence of same frequencys of these fields and in relation to the distances of the sources{reflectors}) one has to take the boundary conditions into account.Doesn't all this new paper just make it a photon rocket?
If your referring to the paper where they state that two overlapping photons escape the cavity.Just found this paper entitled "On the Exhaust of Electromagnetic Drive" submitted by Grahn, Annila, and Kolehmainen in the journal AIP Advance:
If so my thoughts on that I think you might be right in that I don't see it being much more than a photon rocket (non recycled). Depending on the mass escaping would determine the ratio of energy transferred to the cavity. With out repeated reflections such as a recycled photon rocket I don't see how that much energy could be transferred unless the mass of the escaping photons was some how large.
http://dx.doi.org/10.1063/1.4953807
The authors postulate a potential theoretical underpinning for the EM drive effect which appears to be at least a partial departure from current theories and which also addresses problems wrt momentum conservation. I'm not qualified to comment on its veracity, but several here are. I'm curious to see what those well versed the relevant subject matter have to say...
Sent from my iPad using Tapatalk
One idea behind the recycling of photons here:[...
The other problem I see is that in a cavity, light is reflected because the current moves in the direction of the light stimulating it. When current moves in the direction light stimulates it this generates light that is opposite in phase to the light stimulating it. In effect if one imagines the stimulating light over lapping the light from the stimulated current they form overlapping light with destructive properties such that the light appears to disappear. On the other hand new light is created by the effect such that it appears to be a reflection of the stimulating light.
My point is this destructive interference of light should happen everywhere in the cavity (where ever there is a reflection). Maybe they are suggesting this destructive interference is only happening on one side?
A phased array works much the same in that this destructive interference happens on one side of the phased array while not on the other side. Thus a phased array can spit out light in a direction it wants by controlling the relative phase of current in its array.
Edit: also, in essence the concept of modifying the mass of light at one end of the cavity, I feel is connected to the Woodward or Mach effect. That is we have an object of mass that receives an impulse. We then change its effective mass and give it an impulse in the other direction. After repeated collisions the energy is more effectively transferred from the light to the cavity than would be possible with a single collision (a solar sail for example receives a small Doppler shift per impulse, but the Doppler shift is greater with many reflections when dealing with a recycled photon rocket, or possibly by modifying the photon mass at the narrow end of the cavity.)
In the paper where they discuss a greater impulse by photons in a medium (my empty quote link) and attribute it to a larger momentum I feel what they may be measuring is actually an increased transfer of energy via the change in relative mass of the photon.
The small frequency shift leads to a greater bandwidth of the resonance and lowers the Q(dissipation factor). -
#3226 by dustinthewind on 17 Jun, 2016 23:39
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In fact there is both destructive and constructive interference of interacting EM fields inside a cavity (especially with defined positions of the nodes and antinodes in the presence of same frequencys of these fields and in relation to the distances of the sources{reflectors}) one has to take the boundary conditions into account.
The small frequency shift leads to a greater bandwidth of the resonance and lowers the Q(dissipation factor).
I agree, though I was specifically addressing the boundary where the metal current interacts with the light (where destructive interference may allow "invisible" light to escape the cavity - e.g. actually a reflection), but yeah there is also destructive and constructive interference of the light in the cavity as well. I think I remember trying to illustrate that some time ago too.
Edit: an interesting question comes to mind with the photon recycling thruster with 2 mirrors. Light reflects off one mirror and that mirror is accelerated such that the light is Doppler shifted due energy lost. The wavelength of the light is constantly changing but the mirrors have a defined spacing such that light may not be happy with their spacing. Just because the distance isn't just right between the mirrors I would guess that the light still exists between those mirrors. Not sure exactly where I am going with that though. Just a random thought.
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#3227 by FattyLumpkin on 18 Jun, 2016 00:55
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A second try at the question Given:1)Two cavities, one is high Q the other low or no Q. * The
high Q cylinder is resonant in that it resonates in a
given mode: e.g TE 012 or other.
2) Both cavities are of equal volume
3) RF is being fed into both cavities of equal
power and frequency.
4) Each cavity has a waveguide/collimator of equal
size, designed to efficiently guide the RF from
each cavity (are matched to the given inflow
frequency). They are not small holes.
Question: Is there a difference between the RF being expelled from the collimating guides?
If so please characterize the difference(s). Please see attached * an error in the drawing : an "arrow" is missing pointing to the upper cavity collimator guide.
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#3228 by mwvp on 18 Jun, 2016 01:49
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Of course. That's why its called "Rocket Science", done by "Rocket Scientists" with slide-rules and pocket protectors.....I can spell it out with examples. But I'd rather leave it to my more formal, and less impaired betters. Momentum may divide linearly, but energy depends on velocity or voltage squared. ...
Sorry, but the situation is worse than that for momentum for spacecraft propulsion . To enable spacecraft propulsion, momentum is a nonlinear function, because of variable mass in kinetic momentum.
Alas, I'm just a sniveling engineer with a computer
Also, the electromagnetic momentum in vacuum:
...
does not "divide evenly" either, in the sense that it is also a nonlinear function:
and
With the E and B out of phase sinusoidal functions of time with frequency f, the electromagnetic momentum is a square harmonic function of time: the momentum will have frequency 2 f.
But a waveguide is linear and reciprocal. A quarter wave matching network isn't reciprocal in a network context, but and EM system (sans semiconductors, electron-tubes or other non-linear devices) is well-behaved compared to a non-linear acoustic-levitation context.Also, kinetic momentum only "divides evenly" in the sense of being a linear function of velocity only for small velocities, for constant mass. Even considering Special Relativity, the momentum is a very nonlinear function of velocity, due to the change in mass (*):
Of course. I'm neglecting that to consider my point, which was regarding matching energy source impedance to energy load impedance. If you say you can give my 3uN/kW of force from an actuator, it can be very good, even over-unity source of "free energy", or abysmally inefficient, depending on a gear box to match it to a load.
Quarter wave lines match impedance. If its matching a low impedance to a high-impedance source, energy resonates on the line till its amplitude builds up to a high enough potential, losses lower Q notwithstanding.
Also non-conventional propellant-less drives like Woodward's relies on variable mass as well for propulsion:.
I find the papers describing confined waveguide EM as having mass intriguing. Accelerate such a high-Q waveguide, doppler-spreading the EM, then selectively filter the lower sideband anisotropically at one end, such that a travelling wave anisotropically propates, and would the math show an equivallent mass-flow?
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#3229 by mwvp on 18 Jun, 2016 01:57
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...
Edit: an interesting question comes to mind with the photon recycling thruster with 2 mirrors. Light reflects off one mirror and that mirror is accelerated such that the light is Doppler shifted due energy lost. The wavelength of the light is constantly changing but the mirrors have a defined spacing such that light may not be happy with their spacing. Just because the distance isn't just right between the mirrors I would guess that the light still exists between those mirrors. Not sure exactly where I am going with that though. Just a random thought.
Well, if the light decided it wasn't happy and tunneled out, I suspect someone would have noticed a conservation of energy problem. I can recommend a place to go with it though:
http://www.falstad.com/dispersion/group.html
Feast! -
#3230 by Left Field on 18 Jun, 2016 06:45
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A quick link to a great show given by an astrophysics professor that explains visually why confined photons are responsible for inertial and gravitational mass.
Of course. That's why its called "Rocket Science", done by "Rocket Scientists" with slide-rules and pocket protectors.....I can spell it out with examples. But I'd rather leave it to my more formal, and less impaired betters. Momentum may divide linearly, but energy depends on velocity or voltage squared. ...
Sorry, but the situation is worse than that for momentum for spacecraft propulsion . To enable spacecraft propulsion, momentum is a nonlinear function, because of variable mass in kinetic momentum.
Alas, I'm just a sniveling engineer with a computerAlso, the electromagnetic momentum in vacuum:
...
does not "divide evenly" either, in the sense that it is also a nonlinear function:
and
With the E and B out of phase sinusoidal functions of time with frequency f, the electromagnetic momentum is a square harmonic function of time: the momentum will have frequency 2 f.
But a waveguide is linear and reciprocal. A quarter wave matching network isn't reciprocal in a network context, but and EM system (sans semiconductors, electron-tubes or other non-linear devices) is well-behaved compared to a non-linear acoustic-levitation context.Also, kinetic momentum only "divides evenly" in the sense of being a linear function of velocity only for small velocities, for constant mass. Even considering Special Relativity, the momentum is a very nonlinear function of velocity, due to the change in mass (*):
Of course. I'm neglecting that to consider my point, which was regarding matching energy source impedance to energy load impedance. If you say you can give my 3uN/kW of force from an actuator, it can be very good, even over-unity source of "free energy", or abysmally inefficient, depending on a gear box to match it to a load.
Quarter wave lines match impedance. If its matching a low impedance to a high-impedance source, energy resonates on the line till its amplitude builds up to a high enough potential, losses lower Q notwithstanding.
Also non-conventional propellant-less drives like Woodward's relies on variable mass as well for propulsion:
I find the papers describing confined waveguide EM as having mass intriguing. Accelerate such a high-Q waveguide, doppler-spreading the EM, then selectively filter the lower sideband anisotropically at one end, such that a travelling wave anisotropically propates, and would the math show an equivallent mass-flow?
This video also mentions how particle and photon pressure can also affect space-time, which also comes up in this fascinating video that shows how negative pressure is driving the acceleration in the expansion of the universe!
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#3231 by SeeShells on 18 Jun, 2016 12:51
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Morning coffee thoughts.
Some theories think that they increase the effective mass of the photon shifting the center of mass within the frustum leading to the effect we are seeing.
If that was the case we would see on a torsional pendulum an effect we could set up to see a defection of a laser. It would take a beam 90o splitter on the frustum and a laser on the fulcrum center pivot wire.
It would seem we're not testing all the axis's possible directional motions addressing the several theories put forth in a test.
Any thoughts?
Shell
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#3232 by Mulletron on 18 Jun, 2016 15:11
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A cone coil. It looks like he's got a DC source and a hand switch which he's turning on and off in time with the swing. He's getting torque and linear movement. Six videos altogether.
Edit: Man if this thing really works (not getting my hopes up), but if it does, the EMDrive just got Bates 4000'd. I bet you anything that the EMDrive is broken because it's gotta be open.
Edit 2: Based on what I was talking about a few posts ago* about closed and open surfaces, and the above video (still awaiting verification), here's what I'm thinking. The EMDrive should be open at both ends (might be dangerous), supporting TE modes of operation only, and for gravitoelectromagnetic operation, you can fully enclose the cavity again (like it is now) and put an open surface around it.
* http://forum.nasaspaceflight.com/index.php?topic=39772.msg1547942#msg1547942
http://forum.nasaspaceflight.com/index.php?topic=39772.msg1548387#msg1548387
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#3233 by X_RaY on 18 Jun, 2016 18:44
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A second try at the question Given:1)Two cavities, one is high Q the other low or no Q. * The
Your choice of mode is interesting in regard to the position of the waveguide in the cylindrical case. For this mode TE012 the H field produces circular currents at the endplates. For this special mode the outcoupling rate into this waveguide at this coordinates will be quite low.
high Q cylinder is resonant in that it resonates in a
given mode: e.g TE 012 or other.
2) Both cavities are of equal volume
3) RF is being fed into both cavities of equal
power and frequency.
4) Each cavity has a waveguide/collimator of equal
size, designed to efficiently guide the RF from
each cavity (are matched to the given inflow
frequency). They are not small holes.
Question: Is there a difference between the RF being expelled from the collimating guides?
If so please characterize the difference(s). Please see attached * an error in the drawing : an "arrow" is missing pointing to the upper cavity collimator guide.
In the other case with the irregular shape its hard to say what happens, the coupling rate to the waveguide depends on the waveform and wall currents at/near the penetration point.
Over this, very low Q means higher losses and therefore in general lower fieldstrength.
And it's unlikely (based on your sketch) that both cavities resonates with the same mode at the same frequency.
No one can answer your question without knowledge about any concrete geometries and frequency.
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#3234 by FattyLumpkin on 18 Jun, 2016 18:50
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X_Ray, what mode would best suit the high Q cylinder for generating the best force (out of) from the guide collimator?
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#3235 by X_RaY on 18 Jun, 2016 19:04
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What mode would best suit the high Q cylinder for generating the best force (out of) from the guide collimator?
I don't understand this kind of construction of a simple photon rocket at all, it lowers the efficiency caused by losses in the cavity.
On the other hand if you like to use such design as a plasma thruster, I would focus in modes with high gradient of the E-field in propagation direction. -
#3236 by Rodal on 18 Jun, 2016 19:11
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A second try at the question Given:1)Two cavities, one is high Q the other low or no Q. * The
You are not changing the momentum of the photons by changing the quality factor Q.
high Q cylinder is resonant in that it resonates in a
given mode: e.g TE 012 or other.
2) Both cavities are of equal volume
3) RF is being fed into both cavities of equal
power and frequency.
4) Each cavity has a waveguide/collimator of equal
size, designed to efficiently guide the RF from
each cavity (are matched to the given inflow
frequency). They are not small holes.
Question: Is there a difference between the RF being expelled from the collimating guides?
If so please characterize the difference(s). Please see attached * an error in the drawing : an "arrow" is missing pointing to the upper cavity collimator guide.
It is important to understand the physical meaning of Q.
The quality factor Q is a measure inverse to damping, low Q means high damping and high Q means low damping.
Using Maxwell's equations and Special Relativity (no new physics), trying to maximize the thrust of a photon rocket by a resonant chamber with high Q would be like trying to maximize the thrust of a chemical rocket by introducing high oscillations with low damping.
Such oscillations occur in chemical rockets, most famously in the Saturn V rocket that took the Apollo to the Moon and the N1 rocket that the Soviets were trying to use to send cosmonauts to the Moon. Such self-excited oscillations in chemical rockets are called POGO oscillations. If they reach an amplitude high enough they can lead to structural destruction of the rocket, but as to increasing thrust? No they don't increase thrust of the chemical rocket.
See:
https://en.wikipedia.org/wiki/Pogo_oscillationQuoteOne of the Soviet Union's N1-L3 rocket test flights suffered pogo oscillations in the first stage on February 21, 1969. The launch vehicle reached initial engine cutoff, but exploded 107 seconds after liftoff and disintegrated.[5] There are other cases during unmanned launches in the 50s and 60s where the pogo effect caused catastrophic launch failures.
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#3237 by FattyLumpkin on 18 Jun, 2016 19:23
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Plasma as in Gas Dynamic Mirror...I'm not thinking along those lines: more like the LASER, but using microwaves in resonance, expelling high density resonant waves from the collimator/waveguide. The assertion being that the resonant energy being "guided" out of the
resonant cavity is of increased mass/density of momentum and there bye generating > 3.3 micro Newtons of force/ thrust.
Dr. Rodal, your post made it just before mine, thank you for your response.
So "loading" of the cavity and the resonant state does not? result in an increase of the total the number/density of photons being expelled from the collimating guide, or in a closed frustum for that matter.
I have to admit I'm lost at the comparison with POGO, as POGO is a mechanical translation of pressure waves from the rocket's combustion chamber. I am given to understand the density and/or power of EM radiation waves can result in no mechanical action (oscillations). -
#3238 by Rodal on 18 Jun, 2016 20:08
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...
Dr. Rodal, your post made it just before mine, thank you for your response.
So "loading" of the cavity and the resonant state does not? result in an increase of the total the number/density of photons being expelled from the collimating guide, or in a closed frustum for that matter.
I have to admit I'm lost at the comparison with POGO, as POGO is a mechanical translation of pressure waves from the rocket's combustion chamber. I am given to understand the density and/or power of EM radiation waves can result in no mechanical action (oscillations).
1) The quality factor Q is not defined by "an increase of the total the number/density of photons"
It is important to understand the physical meaning of Q.
Q is used for mechanical vibrations as well as for electromagnetic vibrations. The definition is clear, it is just an inverse measure of damping ζ:
2) POGO are self excited oscillations inside the chamber of a chemical rocket. They were brought as an analogy to help understand that having a high Q oscillation in the chamber of a chemical rocket does not increase thrust.
And that therefore using standard physics (no new physics) there is no basis to expect that the thrust of a photon rocket would increase by producing electromagnetic oscillations in a resonant chamber with high Q.
The purpose is to help understand that Q has to do with damping of oscillations and has nothing to do with creation or destruction of particles.
As X-Ray mentioned, the damping in an electromagnetic metallic cavity (and hence the Q lower than infinity) is due to the power loss incurred in the metal surface with a penetration equal to the skin depth, due to imperfect conductivity of the metal. Again, it has to do with the conductivity of the metal and NOT with photon production.
Using a superconducting cavity increases the Q by decreasing damping. This increased Q is due to increased conductivity of the metal, and not to creation or destruction of photons. -
#3239 by X_RaY on 18 Jun, 2016 20:34
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In fact it depends on the coupling factor of the waveguide to the cavity and how much RF energy can escape. (The waveguides may having the same impedance miss match to free space in bothe cases, FL sketch)
