Hi Kaushik, I think you're right, I really need to increase the resolution a lot! like from 50 to 200 to have precision at 18GHz. Do you think this is possibile? Matteo
On Thu, Feb 11, 2010 at 4:23 PM, <[email protected]> wrote: > Hi Matteo, > Did you increase the resolution and check if the result changes significantly? > Kaushik > > Quoting Matteo Bassi <[email protected]>: > >> Dear Meep users and Dear Prof. Johnson, >> >> I'd like to check the attenuation and phase shift of a plane wave to >> understand if I'm setting the material parameters correctly. >> >> My unit is a=1e-2 and my central frequency is 6Ghz, hence 0.2 in Meep units. >> >> My material epsilon=100 and sigma=4 [S/m]. >> In Meep this means epsilon=100 and >> d-conductivity=a/c*4/100/epsilon_0=0.0094 (right?) >> >> I'm using this code to create the plane wave: >> >> ==== code start ==== >> >> (define-param sxc 40) ; the x size of the computational cell, not including >> PML >> (define-param syc 50) ; the x size of the computational cell, not including >> PML >> (define-param dpml 1) ; thickness of PML layers >> >> (define sx (+ sxc (* 2 dpml))) ; cell size, including PML >> (define sy (+ syc (* 2 dpml))) ; cell size, including PML >> >> (set! geometry-lattice (make lattice (size sx sy no-size))) >> (set! default-material (make dielectric (epsilon 100) >> (D-conductivity 0.0094) >> (mu 1) >> )) >> >> (set! pml-layers (list (make pml (thickness dpml)))) >> (set-param! resolution 15) >> >> >> (define-param fcen 0.2) ; pulse center frequency >> (define-param df 0.1) ; turn-on bandwidth >> >> >> (set! sources >> (list >> (make source >> (src (make continuous-src (frequency fcen) (fwidth df))) >> (component Ez) (center -19 0) (size 0 sy) >> ) >> ) >> ) >> >> >> (define-param T 250) ; run time >> (run-until T >> (at-end output-efield-z) >> (to-appended "src" (at-every 0.2 (in-point (vector3 -19 0) >> output-efield-z))) >> (to-appended "tgt-1" (at-every 0.2 (in-point (vector3 -14 0) >> output-efield-z))) >> (to-appended "tgt-2" (at-every 0.2 (in-point (vector3 -9 0) >> output-efield-z))) >> ) >> >> >> ==== code stop ==== >> >> as you can see the source is at -19cm, and the 2 points where I'm >> looking at at -14cm and -9cm. the distance between this 2 points is >> 5cm. >> >> from Pozar, I calculated the complex propagation factor as: >> >> k = j * 2 * pi * f * sqrt( mu0 * (er * e0 - j * sigma / (2 * pi * f) ) ) >> >> the expected attenuation is -2.04dB and I get -2.24dB >> given the peak of the wave at 9cm, I expect that peak to be in the >> wave at 14cm t=imag(k)/omega * 5cm = 1.6674e-9. however there is no >> peak at that point >> >> what s happening? why I cant verify mathematically what Im looking for? >> is the way I'm generating the plane wave good enought to do this calculation? >> >> Thanks to everybody who can help me! >> Matteo >> >> _______________________________________________ >> meep-discuss mailing list >> [email protected] >> http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss >> > > > -- Matteo Bassi, PhD Student Department of Information Engineering University of Padova _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
