Shell,You could always go to a klystron.D
People seem to like 2.4 Ghz because of the availability of magnetrons for it, but there's a lot of RF noise in that band. Magnetrons seem to be dismissed because of their noisiness (even if there are ways to stabilize them, does it matter at experimenter's power levels?)
Quote from: Bob Woods on 05/24/2017 12:50 amQuote from: Star-Drive on 05/23/2017 06:43 pmAll: "Apprentice Sorcerer Gravity Appliances Reaction Devices (ASGARD) works for me! I just hope Thor doesn't mind...Boy, be busy and you miss the fun. What about "Paul's Texas Quantum Bar and Boson BBQ"I think that the "Boson BBQ" may be more appropriate for Shells since, apparently, she likes roasting antennas
Quote from: Star-Drive on 05/23/2017 06:43 pmAll: "Apprentice Sorcerer Gravity Appliances Reaction Devices (ASGARD) works for me! I just hope Thor doesn't mind...Boy, be busy and you miss the fun. What about "Paul's Texas Quantum Bar and Boson BBQ"
All: "Apprentice Sorcerer Gravity Appliances Reaction Devices (ASGARD) works for me! I just hope Thor doesn't mind...
Quote from: R.W. Keyes on 05/28/2017 06:39 amPeople seem to like 2.4 Ghz because of the availability of magnetrons for it, but there's a lot of RF noise in that band. Magnetrons seem to be dismissed because of their noisiness (even if there are ways to stabilize them, does it matter at experimenter's power levels?) I like 2.45Ghz as that frequency band is unlicensed and therefore safe to leak into. I would hate to have the FCC call as those fines are quite substantial. Magnetrons also require cooling to keep the frequency stable. If it is not actively cooled, then runaway thermal heating causes the frequency to drift lower, eventually damaging the magnetron. The frequency drift makes holding resonance very difficult and active cooling makes precise measurements very difficult.
Squeezed Electromagnetic Vacuum:...-One can "squeeze" variance of one observable provided variance in conjugate observable is stretched- Observable that gets squeezed will have its fluctuations reduced below the vacuum ZPFo Since the vacuum is defined to have vanishing energy density, any region with less energy density than the vacuum actually has a negative (renormalized) expectation value for the energy density
The uncertainty principle puts a lower limit on the product of the variance in the amplitude (or number) of photons and the variance in the phase. Vacuum photons naturally have equal variance in both amplitude and phase. It is, however, possible to create a "squeezed state" of light, in which either one of these quantities is minimized (squeezed) and the other is allowed to increase (antisqueezed).
The Hannover team has now improved several aspects of its instrumentation. Most significantly, they have used a new, doubly resonant cavity: "You need two wavelengths to generate the squeezed light and we had a resonator that was resonant for both," explains team member Moritz Mehmet. In addition, says his teammate Henning Vahlbruch, they upgraded several other features: "We used the best available materials, a different cavity topology and custom-made photodetectors." The researchers broke their own record, squeezing vacuum photons by a factor of 32.
freq. GHz Q Amp Amp SI Comp freq. Diff. end2451314734.6915 2.45131 34,362 0.29088 1.10E+02 ex 0 SE 2451314734.69151 2.45131 34,362 0.29088 1.10E+02 ey 0 SE 2441943271.04085 2.44194 -13,481 0.00000 2.07E-15 ez SE2451262522.54508 2.45126 968 0.00000 5.29E-15 ez SE2465495123.57696 2.46550 2,452 0.00000 9.35E-15 ez SE 2451315953.25884 2.45132 35,297 1.14531 1.14531 hx 0 SE 2451315953.25884 2.45132 35,297 1.14531 1.14531 hy 0 SE 2451315922.70902 2.45132 35,431 0.36909 0.36909 hz 0 SE 2451314755.05473 2.45131 34,545 0.00439 1.65E+00 ex -20.36323452 BE 2451314755.05472 2.45131 34,545 0.00439 1.65E+00 ey -20.3632049561 BE 2451571816.19804 2.45157 560 0.00000 5.54E-14 ez BE2457576614.11381 2.45758 313 0.00000 2.48E-13 ez BE2465596829.68202 2.46560 5,955 0.00000 1.50E-14 ez BE 2451315943.00494 2.45132 35,343 1.73483 1.73483 hx 10.2538976669 BE 2451315943.00495 2.45132 35,343 1.73483 1.73483 hy 10.2538948059 BE 2451316625.84456 2.45132 35,418 0.07332 0.07332 hz -703.1355333328 BE
(...)One more thing: I had a dear friend donate a new/old Tektronix O-Scope for the lab, there is something about a simple O-scope that I love, the new stuff on the computer via the USB port is OK but green wiggly lines on a CRT make me smile a lot.
freq. GHz Q Amp Amp SI Comp freq. Diff. end2451314734.6915 2.45131 34,362 0.29088 1.10E+02 ex 0 SE2451314734.69151 2.45131 34,362 0.29088 1.10E+02 ey 0 SE2441943271.04085 2.44194 -13,481 0.00000 2.07E-15 ez SE2451262522.54508 2.45126 968 0.00000 5.29E-15 ez SE2465495123.57696 2.46550 2,452 0.00000 9.35E-15 ez SE2451315953.25884 2.45132 35,297 1.14531 1.14531 hx 0 SE2451315953.25884 2.45132 35,297 1.14531 1.14531 hy 0 SE2451315922.70902 2.45132 35,431 0.36909 0.36909 hz 0 SE2451314755.05473 2.45131 34,545 0.00439 1.65E+00 ex -20.36323452 BE2451314755.05472 2.45131 34,545 0.00439 1.65E+00 ey -20.3632049561 BE2451571816.19804 2.45157 560 0.00000 5.54E-14 ez BE2457576614.11381 2.45758 313 0.00000 2.48E-13 ez BE2465596829.68202 2.46560 5,955 0.00000 1.50E-14 ez BE2451315943.00494 2.45132 35,343 1.73483 1.73483 hx 10.2538976669 BE2451315943.00495 2.45132 35,343 1.73483 1.73483 hy 10.2538948059 BE2451316625.84456 2.45132 35,418 0.07332 0.07332 hz -703.1355333328 BE
Quote from: SeeShells on 05/28/2017 02:48 pm(...)One more thing: I had a dear friend donate a new/old Tektronix O-Scope for the lab, there is something about a simple O-scope that I love, the new stuff on the computer via the USB port is OK but green wiggly lines on a CRT make me smile a lot. Shell,that O-scope may have been built in Guernsey C.I. off the coast of France (where I grew up!)
@dustinthewindYes, you are right. Feynman discusses this in his great book, the Feynman Lectures on Physics, Vol 2, and he's very good at explaining it in a way that makes sense. It's called the guide wavelength. In a waveguide, like a fiberoptic cable or an resonance cavity, the interaction with the walls causes an interference pattern that behaves as if the light has a longer wavelength and the same frequency, causing a strange effect as the "phase velocity" and the "group velocity" of the light to go out of sync.
Hi,I'm not a regular here, but I am running an organization to try to put an EMDrive into orbit on a CubeSat and demonstrate whether it works in-situ. I have 3 minutes at the Smallsat Conference in Logan, UT, this summer to present a brief overview of the "state of the art" of EMDrive, and I have an opportunity to submit a paper along with my talk. I was thinking of including the attached document as an appendix, and I was hoping one of you could look at it and tell me what you think of it, or if it would be worth it. I don't know if it is useful, or even something everyone already knows. I'm sure it's not something helpful to someone with access to COMSOL, but I am not among that number.It is a an attempt to derive an equation for the cut-off diameter in a frustum in TM mode, given that (I believe) the equations for the cut-off for a cylinder are not valid for that case.A little about my project: www.buildanemdrive.org is a non-profit to raise money to put a test article of the EMDrive into orbit on a CubeSat. I am working on a test article myself, and I am currently working with the State Department to try to get approval to make it open source. I am interested in partnering with other groups that want the chance to go to orbit and I will share any funds raised towards a launch with whoever is ready to fly and will likely provide a definite answer of whether an EMDrive will work free of testing equipment and in control. If enough people are interested, I think we can put together a judging event with celebrity judges at one of the annual space conferences, or something like that. Fundraising is going a bit slowly just now, mostly because I have to choose between making progress on my drive and doing fundraising. Please let me know if you are interested in working together. If you are unwilling to share technical data, that's OK; I don't really need to know that right now.Sorry to be a bit terse. If anyone has any questions, I'll try to answer them.
Quote from: JonCard on 05/31/2017 04:23 amHi,I'm not a regular here, but I am running an organization to try to put an EMDrive into orbit on a CubeSat and demonstrate whether it works in-situ. I have 3 minutes at the Smallsat Conference in Logan, UT, this summer to present a brief overview of the "state of the art" of EMDrive, and I have an opportunity to submit a paper along with my talk. I was thinking of including the attached document as an appendix, and I was hoping one of you could look at it and tell me what you think of it, or if it would be worth it. I don't know if it is useful, or even something everyone already knows. I'm sure it's not something helpful to someone with access to COMSOL, but I am not among that number.It is a an attempt to derive an equation for the cut-off diameter in a frustum in TM mode, given that (I believe) the equations for the cut-off for a cylinder are not valid for that case.A little about my project: www.buildanemdrive.org is a non-profit to raise money to put a test article of the EMDrive into orbit on a CubeSat. I am working on a test article myself, and I am currently working with the State Department to try to get approval to make it open source. I am interested in partnering with other groups that want the chance to go to orbit and I will share any funds raised towards a launch with whoever is ready to fly and will likely provide a definite answer of whether an EMDrive will work free of testing equipment and in control. If enough people are interested, I think we can put together a judging event with celebrity judges at one of the annual space conferences, or something like that. Fundraising is going a bit slowly just now, mostly because I have to choose between making progress on my drive and doing fundraising. Please let me know if you are interested in working together. If you are unwilling to share technical data, that's OK; I don't really need to know that right now.Sorry to be a bit terse. If anyone has any questions, I'll try to answer them.On Thread 3, two years ago, 06/21/2015 08:07 PM, I posted:https://forum.nasaspaceflight.com/index.php?topic=37642.msg1392223#msg1392223with this attachment report, titled:Cut-off of Resonant Modes in Truncated Conical Cavities:https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1030954;sess=45576
I have not had a chance to read your papers yet, but in regards to the change in speed, yes, sort of. The velocity that increases is the "phase velocity"; another speed called the "group velocity" is actually lower. There's a good graphic about the difference on Wikipedia (https://en.m.wikipedia.org/wiki/Phase_velocity). Because it is not the velocity of the photons themselves, it's not clear whether Planck's constant can be used with it, since it isn't quantised energy packets like a photon. Obviously, the whole is a bit up in the air because of this device, but I think observed thrust is in the direction of the small end.
@dustinthewind - Well, in a standing wave the phase velocity is 0, too. ...
Think of a stationary wave as the sum of two travelling waves. If the two waves move in opposite directions and have the same frequency, the result is a stationary wave. The travelling waves have a well defined speed (or phase velocity). You're allowed to do this because of the principle of superposition.
Light traveling through the vacuum interacts with virtual particles similarly to the way that light traveling through a dielectric interacts with ordinary matter. And just as the permittivity of a dielectric can be calculated, the permittivity ϵ0 of the vacuum can be calculated, yielding an equation for the fine-structure constant α. The most important contributions to the value of α arise from interactions in the vacuum of photons with virtual, bound states of charged lepton-antilepton pairs. Considering only these contributions, the fully screened α≅1/139