Hey everyone,Here is a summary of our current experimental design. Any feedback is welcome and appreciated. Kurt

Spurious thoughts and ideas for those considering home (not lab) experimentation...The frustum effect theoretically can be tested a low power levels (see the 25 GHz experiment at just a few milliwatts). My suggestion, and likely my route, will not use 2.45 GHz magnetrons for safety reasons and cabling issues.I'll likely turn to the other large marketplace for 2.4 GHz products...wifi/wlan (802.11b/g). wifi home routers are about 40 mWatts or so with outboard amps that can take that to about 5 watts. Signal sources for a few dozen mWatts (don't have to be wifi only) are all over the place: http://www.mr-lee-catcam.de/pe_cc_i10.htm with 3W amps here: http://amzn.com/B00BX9YZI0 (bidirectional operation is not required for non-wifi use) There are many more out there, so don't stop here.Other than safety, weight measurements will be easier. Lower power test units can be battery operated, avoiding the need for cable routing, potentially skewing weight measurements. IOW, a frustum and signal source can be built and self contained, no strings, er ah, cables attached.Just a thought for home workshop folks. Be safe out there.

Short snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ Cutoff

Quote from: rfmwguy on 06/01/2015 07:50 PM(...)A word of caution to those trying to use these low, low power sources. If the losses of the cavity outweigh the supply, then the Q = 0, since no energy can be stored. So you really need a feel for what the cavity losses will be before you can propose using such a small input source. If all the input power is dissipated in 1 cycle, there is nothing left over to amplify.Todd

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Quote from: WarpTech on 06/01/2015 08:56 PMQuote from: rfmwguy on 06/01/2015 07:50 PM(...)A word of caution to those trying to use these low, low power sources. If the losses of the cavity outweigh the supply, then the Q = 0, since no energy can be stored. So you really need a feel for what the cavity losses will be before you can propose using such a small input source. If all the input power is dissipated in 1 cycle, there is nothing left over to amplify.ToddAgreed, this is the primary reason I decided against dielectric materials. "Electric losses in such cavities are almost exclusively due to currents flowing in cavity walls. " http://en.wikipedia.org/wiki/Microwave_cavity (and many other sources), so unless I'm missing something, copper is the way to go since oxidation (resistance) over time is not a concern. I'm also going to avoid tuning plates so as not to introduce any potential mechanically caused resistances...my head on straight?

Quote from: phaseshift on 06/01/2015 06:35 PMShort snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ CutoffBefore doing Df or resonance calc you need to know excitation mode TMm,n,p or TEm,n,p and the appropriate BesselJ value as per that mode. BesselJ value is driven by mode TE or TM and the associated m & n values. p refers to the number of 1/2 waves between the end plates. There are 2 tables provided. One for TE mode and one for TM mode. Each is indexed by the selected m & n values.As example to use TE013 mode, use the TE table and the value at the intersection of the m=0 & n=1. = 3.8318 Then adjust end plate spacing or frequency or Df, via altering either/both end plate diameters to fit the desired number of p 1/2 waves between the end plates.Tables attached.

Quote from: TheTraveller on 06/01/2015 09:17 PMQuote from: phaseshift on 06/01/2015 06:35 PMShort snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ CutoffBefore doing Df or resonance calc you need to know excitation mode TMm,n,p or TEm,n,p and the appropriate BesselJ value as per that mode. BesselJ value is driven by mode TE or TM and the associated m & n values. p refers to the number of 1/2 waves between the end plates. There are 2 tables provided. One for TE mode and one for TM mode. Each is indexed by the selected m & n values.As example to use TE013 mode, use the TE table and the value at the intersection of the m=0 & n=1. = 3.8318 Then adjust end plate spacing or frequency or Df, via altering either/both end plate diameters to fit the desired number of p 1/2 waves between the end plates.Tables attached.And what? The above method coming directly out of your spreadsheet and produces the same values - I had to bounce all over to pull all the cells together and then simplify all the duplicate references - not sure what you're trying to point out - other than for people to use the above tables to pick a value for jC?

.. the thrust happens due to the interference between the standing wave k and the evanescent wave Beta, phase factors. Where they interfere is where the phase shift is happening due to attenuation, as it propagates into the small end. Optimal thrust will occur when the amplitude of the standing waves is nearly the same as the amplitude of the evanescent waves and the two are out of phase. ...I'm still trying to crunch all this into design equations that are hopefully, more accurate and informative. It may take me a while.Todd

First post here, but have been following Shawyers claims for years. As an ex microwave engineer, just a few thoughts on your design. Short of getting into superconductive cavities, the ideal would be a silver plated, machined and highly polished copper cavity, with the large end plate in contact with the frustum walls using standard RF fingers (also silver plated). Orbel is one typical manufacturer. The end plate could then be actively tuned, in almost real time, using a small stepper motor or servo driven by a network analyser reading S21 and S12 to achieve an active match (highest Q), even in conditions of magnetron or thermal drift.Also note that the vacuum conditions you mention are smack in the middle of Crookes radiometer operating pressures (best thrust from thermal effects), probably not what you want to see. To truly alleviate thermal (gas buoyancy or molecular rebound) effects, you may want to aim for 1 uTorr or better.

I should know better than to post a 1st draft of anything, but here goes nothing... What I've done is put together all of the pieces we have been working on, between Egan, Yang, De Aquino and Shawyer. What I ended up with didn't surprise me. What did is how much this "mimics" gravity in the PV Model is not even funny!Let the show begin!Todd