I am glad you brought this up as I was also contemplating if this was possible. I was thinking of doing this with a phased antenna array but at a much lower frequency than it was meant to run. Most of the time the forces will be symmetric so no propulsion but for a fraction of a second when current reverses in one wire the time retarded forces will be non-symmetric. Your wires are perpendicular and could work with some reduced efficiency, but we could also use two parallel wires with the current only slightly out of phase between the wires. If we have a wire spacing of 0.0025m or 0.025cm and the speed of light being about 3E8m/s and we are using your frequency of 300MHz or 3E8Hz then c=f*lambda so wavelength is lambda=c/f = 1m. Normally you would want the wires spaced at 1/4lambda to get projection of radiation for a phased array but you can still get some at lower frequencies if the currents are out of phase. Normally, for 0.0025m wire spacing we would want a frequency of 3E10Hz or 3*10^10Hz to be a quarter wavelength apart. Taking the ratio of the wavelengths we get ratio of tau = 3E8/3E10 = 1E-2 seconds so for 0.01 seconds the time retarded force is non-symmetric before returning to being symmetric. If we are using a sine wave then the current is only a fraction of what it should be = I_max*sin(pi/2*0.01) = 0.015707317311821*I_max but if we use a square pulse that rises rapidly enough then we could get a max current time retarded non-symmetric force interaction for 0.01 seconds which could be used for propulsion. On the other hand you have to wind so that the static electric effects work with the magnetic other wise you just got another phased array antenna. It is interesting to note the forces of the magnetic field in your design you would be observing would be due to electric field tilting which is from other charges approaching a current. The two forces during the non-symmetric cycle would be 90 degrees out of phase so adding them together you would get a force of 2*F_max*sin(pi/4) = 1.4142 instead of the forces directly adding together. The time retarded behavior of wires at 90 angles on the other hand I may have to think about as it is not as simple as two parallel wires.

Quote from: dustinthewind on 12/17/2015 10:38 PMI am glad you brought this up as I was also contemplating if this was possible. I was thinking of doing this with a phased antenna array but at a much lower frequency than it was meant to run. Most of the time the forces will be symmetric so no propulsion but for a fraction of a second when current reverses in one wire the time retarded forces will be non-symmetric. Your wires are perpendicular and could work with some reduced efficiency, but we could also use two parallel wires with the current only slightly out of phase between the wires. If we have a wire spacing of 0.0025m or 0.025cm and the speed of light being about 3E8m/s and we are using your frequency of 300MHz or 3E8Hz then c=f*lambda so wavelength is lambda=c/f = 1m. Normally you would want the wires spaced at 1/4lambda to get projection of radiation for a phased array but you can still get some at lower frequencies if the currents are out of phase. Normally, for 0.0025m wire spacing we would want a frequency of 3E10Hz or 3*10^10Hz to be a quarter wavelength apart. Taking the ratio of the wavelengths we get ratio of tau = 3E8/3E10 = 1E-2 seconds so for 0.01 seconds the time retarded force is non-symmetric before returning to being symmetric. If we are using a sine wave then the current is only a fraction of what it should be = I_max*sin(pi/2*0.01) = 0.015707317311821*I_max but if we use a square pulse that rises rapidly enough then we could get a max current time retarded non-symmetric force interaction for 0.01 seconds which could be used for propulsion. On the other hand you have to wind so that the static electric effects work with the magnetic other wise you just got another phased array antenna. It is interesting to note the forces of the magnetic field in your design you would be observing would be due to electric field tilting which is from other charges approaching a current. The two forces during the non-symmetric cycle would be 90 degrees out of phase so adding them together you would get a force of 2*F_max*sin(pi/4) = 1.4142 instead of the forces directly adding together. The time retarded behavior of wires at 90 angles on the other hand I may have to think about as it is not as simple as two parallel wires. If you were traveling at 99.99999% c, from one end of a 90 degree bent were toward the vertex, I believe the other wire would be observed as almost parallel. Yes? (A parallel line appears to never intersect. The time experienced by an electron traveling down a wire would be "almost forever", thus it would appear as parallel with slight immeasurable convergence over the timeframe in relativistic terms from the reference frame of the electron.

Quote from: oliverio on 12/17/2015 11:19 PMQuote from: dustinthewind on 12/17/2015 10:38 PMI am glad you brought this up as I was also contemplating if this was possible. I was thinking of doing this with a phased antenna array but at a much lower frequency than it was meant to run. Most of the time the forces will be symmetric so no propulsion but for a fraction of a second when current reverses in one wire the time retarded forces will be non-symmetric. Your wires are perpendicular and could work with some reduced efficiency, but we could also use two parallel wires with the current only slightly out of phase between the wires. If we have a wire spacing of 0.0025m or 0.025cm and the speed of light being about 3E8m/s and we are using your frequency of 300MHz or 3E8Hz then c=f*lambda so wavelength is lambda=c/f = 1m. Normally you would want the wires spaced at 1/4lambda to get projection of radiation for a phased array but you can still get some at lower frequencies if the currents are out of phase. Normally, for 0.0025m wire spacing we would want a frequency of 3E10Hz or 3*10^10Hz to be a quarter wavelength apart. Taking the ratio of the wavelengths we get ratio of tau = 3E8/3E10 = 1E-2 seconds so for 0.01 seconds the time retarded force is non-symmetric before returning to being symmetric. If we are using a sine wave then the current is only a fraction of what it should be = I_max*sin(pi/2*0.01) = 0.015707317311821*I_max but if we use a square pulse that rises rapidly enough then we could get a max current time retarded non-symmetric force interaction for 0.01 seconds which could be used for propulsion. On the other hand you have to wind so that the static electric effects work with the magnetic other wise you just got another phased array antenna. It is interesting to note the forces of the magnetic field in your design you would be observing would be due to electric field tilting which is from other charges approaching a current. The two forces during the non-symmetric cycle would be 90 degrees out of phase so adding them together you would get a force of 2*F_max*sin(pi/4) = 1.4142 instead of the forces directly adding together. The time retarded behavior of wires at 90 angles on the other hand I may have to think about as it is not as simple as two parallel wires. If you were traveling at 99.99999% c, from one end of a 90 degree bent were toward the vertex, I believe the other wire would be observed as almost parallel. Yes? (A parallel line appears to never intersect. The time experienced by an electron traveling down a wire would be "almost forever", thus it would appear as parallel with slight immeasurable convergence over the timeframe in relativistic terms from the reference frame of the electron.I think I am not understanding what your getting at. I thought for copper that the electron velocity is very slow. Like milimeters/second for DC current. On the other hand maybe your referencing by 99.999%c as the wave speed in copper? Not sure what that is. Supper conductors do have electron velocities at high speeds. There are fewer free electron Cooper pairs to super-conduct so to get the same current their charges have much higher velocity. I am not really sure this guy has a way to really make the current in the wires out of phase to be honest but I guess it got me thinking about what might be possible with a phased array.

Quote from: oliverio on 12/17/2015 11:19 PMQuote from: dustinthewind on 12/17/2015 10:38 PMI am glad you brought this up as I was also contemplating if this was possible. I was thinking of doing this with a phased antenna array but at a much lower frequency than it was meant to run. Most of the time the forces will be symmetric so no propulsion but for a fraction of a second when current reverses in one wire the time retarded forces will be non-symmetric. Your wires are perpendicular and could work with some reduced efficiency, but we could also use two parallel wires with the current only slightly out of phase between the wires. If we have a wire spacing of 0.0025m or 0.025cm and the speed of light being about 3E8m/s and we are using your frequency of 300MHz or 3E8Hz then c=f*lambda so wavelength is lambda=c/f = 1m. Normally you would want the wires spaced at 1/4lambda to get projection of radiation for a phased array but you can still get some at lower frequencies if the currents are out of phase. Normally, for 0.0025m wire spacing we would want a frequency of 3E10Hz or 3*10^10Hz to be a quarter wavelength apart. Taking the ratio of the wavelengths we get ratio of tau = 3E8/3E10 = 1E-2 seconds so for 0.01 seconds the time retarded force is non-symmetric before returning to being symmetric. If we are using a sine wave then the current is only a fraction of what it should be = I_max*sin(pi/2*0.01) = 0.015707317311821*I_max but if we use a square pulse that rises rapidly enough then we could get a max current time retarded non-symmetric force interaction for 0.01 seconds which could be used for propulsion. On the other hand you have to wind so that the static electric effects work with the magnetic other wise you just got another phased array antenna. It is interesting to note the forces of the magnetic field in your design you would be observing would be due to electric field tilting which is from other charges approaching a current. The two forces during the non-symmetric cycle would be 90 degrees out of phase so adding them together you would get a force of 2*F_max*sin(pi/4) = 1.4142 instead of the forces directly adding together. The time retarded behavior of wires at 90 angles on the other hand I may have to think about as it is not as simple as two parallel wires. If you were traveling at 99.99999% c, from one end of a 90 degree bent were toward the vertex, I believe the other wire would be observed as almost parallel. Yes? (A parallel line appears to never intersect. The time experienced by an electron traveling down a wire would be "almost forever", thus it would appear as parallel with slight immeasurable convergence over the timeframe in relativistic terms from the reference frame of the electron.I think I am not understanding what your getting at. I thought for copper that the electron velocity is very slow. Like milimeters/second for DC current. On the other hand maybe your referencing by 99.999%c as the wave speed in copper? Not sure what that is. Supper conductors do have electron velocities at high speeds. There are fewer free electron Cooper pairs to super-conduct so to get the same current their charges have much higher velocity. I am not really sure this person has a way to really make the current in the wires out of phase other than the delay in information between the wires as the distance grows. If there is something to it then maybe it would have relation to the EM drive as its walls are tapered at an angle also. I guess it just got me thinking about an idea that relates to the phased array antenna and using lower frequencies. Edit2: Ok Oliverio, I see what you mean. So, it would be wave velocity.

There is a simple answer to any configuration of wires, charges, currents, magnets, etc. that claims "reactionless drive":All proposed "self-acceleration" will be equivalent to the reaction from emitted photons. (Most will actually be less efficient than a photon thruster due to emitting radiation in more than one direction.)This is because the derivation of momentum storage in E-M fields assumes conservation of momentum. For any ideas like this to be productive, they either should come with an experimental demonstration of greater thrust than an equivalent power laser, or a new theory of Electromagnetism that would allow it to work. The new theory of electromagnetism would have to be able to replicate all known results including special relativity, photon energy and momentum, etc. It would then need a specific description of how and under what conditions it would diverge from the classical E-M theory. Note that if you come up with a design that you calculate to be a nearly ideal photon thruster at microwave frequencies, it means you invented a highly directional antenna, which may be useful for space communications. This would be a useful discovery, but would be better for "advanced concepts" than "new physics"If you calculate better than a photon thruster using Maxwell's equations, it means you did your math wrong.

To expand briefly on the above, and I may be wrong, it is the case that the photons of the near field and the far field are essentially the same but operating in different configuration. It seems as though an antenna emits near-field photons, but as you scale the power of the antenna, this effect becomes far less noticeable. As I understand as well, a photon emitted by the near field essentially pushes back on the radiator as it enters the far field. So if one could make a directional antenna that only operates in the near field, it should have a greater thrust than the photon rocket, yes?

Quote from: oliverio on 12/18/2015 12:34 AMTo expand briefly on the above, and I may be wrong, it is the case that the photons of the near field and the far field are essentially the same but operating in different configuration. It seems as though an antenna emits near-field photons, but as you scale the power of the antenna, this effect becomes far less noticeable. As I understand as well, a photon emitted by the near field essentially pushes back on the radiator as it enters the far field. So if one could make a directional antenna that only operates in the near field, it should have a greater thrust than the photon rocket, yes?The phrase "only operates in the near field" does not make any sense.Near field is complicated for all but the simplest antennas, since there are various effects that cancel out such as a photon being emitted from one part of the antenna, only to be absorbed by another part.Far field is easier to work with for most applications and includes ALL of the photons that actually escape from the antenna. If these are not symmetrically distributed, then the device is a directional antenna, and photon thruster. The portions of the near field that do not make it to the far field all represent internal interactions between portions of the device and they all cancel (equal and opposite reactions). The far field is therefore the only thing necessary to consider when determining the reaction of the device.The reason photon thrusters are inefficient is due to the Energy momentum relation for all massless particles in special relativity: E = p*c. (E is energy, p is momentum, c is speed of light (a big number))If you want a better EM drive than that, you need to find some kind of modification to the known physical laws. As I said above, this means either a theory that reduces to the existing theory under nearly all cases (because existing theory woks very well), or an experimental result that can't be explained by existing theory.

Do you have any pictures of your drive? Any drive base on radiation pressure will not be better than a photon thruster. You can refer to my drive: http://forum.nasaspaceflight.com/index.php?topic=38996.0

Quote from: ZhixianLin on 12/18/2015 01:50 AMDo you have any pictures of your drive? Any drive base on radiation pressure will not be better than a photon thruster. You can refer to my drive: http://forum.nasaspaceflight.com/index.php?topic=38996.0I don't have a drive, only a thought experiment. I'll make it a bit more relatable. Imagine you have a cylindrical cavity with endplate injection, but one endplate is made from a perfect reflector and the opposite endplate is made from a perfect photodiode (which is returned to the antenna's powersupply) . Assume that the cavity is about as long as the near-far field boundary. So if the photons on one side (the photodiode) are far-field particles they ought to possess less momentum but equal energy to the photon that left the far-field. However, as this photon is absorbed by the photodiode, and electricity is generated, the momentum imparted to the photodiode should be less than the momentum of the emitted photon. Now, side wall pressure may invalidate that-- but now I then ask the following: if the cylinder has tapered walls, is it not the case that from a photon's reference frame, there exists a geometry of frustrum such that relativistic length contraction would make the frustum's walls appear straight to an observer?

Quote from: oliverio on 12/18/2015 02:07 AMQuote from: ZhixianLin on 12/18/2015 01:50 AMDo you have any pictures of your drive? Any drive base on radiation pressure will not be better than a photon thruster. You can refer to my drive: http://forum.nasaspaceflight.com/index.php?topic=38996.0I don't have a drive, only a thought experiment. I'll make it a bit more relatable. Imagine you have a cylindrical cavity with endplate injection, but one endplate is made from a perfect reflector and the opposite endplate is made from a perfect photodiode (which is returned to the antenna's powersupply) . Assume that the cavity is about as long as the near-far field boundary. So if the photons on one side (the photodiode) are far-field particles they ought to possess less momentum but equal energy to the photon that left the far-field. However, as this photon is absorbed by the photodiode, and electricity is generated, the momentum imparted to the photodiode should be less than the momentum of the emitted photon. Now, side wall pressure may invalidate that-- but now I then ask the following: if the cylinder has tapered walls, is it not the case that from a photon's reference frame, there exists a geometry of frustrum such that relativistic length contraction would make the frustum's walls appear straight to an observer?My drive does not need relativity. If your design need relativity, then I can not explain.

Quote from: meberbs on 12/18/2015 01:11 AMQuote from: oliverio on 12/18/2015 12:34 AMTo expand briefly on the above, and I may be wrong, it is the case that the photons of the near field and the far field are essentially the same but operating in different configuration. It seems as though an antenna emits near-field photons, but as you scale the power of the antenna, this effect becomes far less noticeable. As I understand as well, a photon emitted by the near field essentially pushes back on the radiator as it enters the far field. So if one could make a directional antenna that only operates in the near field, it should have a greater thrust than the photon rocket, yes?The phrase "only operates in the near field" does not make any sense.Near field is complicated for all but the simplest antennas, since there are various effects that cancel out such as a photon being emitted from one part of the antenna, only to be absorbed by another part.Far field is easier to work with for most applications and includes ALL of the photons that actually escape from the antenna. If these are not symmetrically distributed, then the device is a directional antenna, and photon thruster. The portions of the near field that do not make it to the far field all represent internal interactions between portions of the device and they all cancel (equal and opposite reactions). The far field is therefore the only thing necessary to consider when determining the reaction of the device.The reason photon thrusters are inefficient is due to the Energy momentum relation for all massless particles in special relativity: E = p*c. (E is energy, p is momentum, c is speed of light (a big number))If you want a better EM drive than that, you need to find some kind of modification to the known physical laws. As I said above, this means either a theory that reduces to the existing theory under nearly all cases (because existing theory woks very well), or an experimental result that can't be explained by existing theory.I certainly follow your logic, I think you're a very sensible poster on this forum. For that reason let me request that you humor my inquiry a bit further. At or before the border between near and far field, which I understand as gradient, force imparted by photons falls off at a less exponential rate than within what is firmly the far-field.So here is a thought experiment which I take to be nonparadoxical to you, but it is not so to me:A laser is attached to (perhaps by a rod) and aimed at an ideal photodiode positioned at the edge of the near-field gradient. The momentum of the photons leaving the laser (inside the near field, right?) should be higher than the ones being "caught" by the photodiode. If this were the case, would it accelerate in open space?

This is because the derivation of momentum storage in E-M fields assumes conservation of momentum.

Thanks for the reply meberbs, this makes sense that the forces experienced in the near-field aren't the same as a classical "baseball gets thrown" analogy for particles.The transition point does not happen at a specific time and place, though, right? As I understand, this is because the zone is a product of gradient self-interference. Does this not imply that we could, by exact positioning of a photodiode, control which virtual photons self-interfere before all photons have actually left it, and create nonsymmetric but conserved forces? (In this context the photodiode is somewhere between the near field and the far field.)

Quote from: meberbs on 12/18/2015 12:18 AMThis is because the derivation of momentum storage in E-M fields assumes conservation of momentum. If the derrivation of momentum storage assumes the conservation laws, then you are deriving it from the combination of Maxwell Equation and Conservation Laws.This is not the same as getting the conservation laws from only Maxwell's equations.So, the conclusion that Maxwell Equations imply Conservation Laws is false.You can't first assume something and then prove it on the basis of the assumption.