On Fri, 4 Jan 2008, [EMAIL PROTECTED] wrote: > Thanks for the earlier reply. I'm trying to run a simple simulation > for the resonant frequencies of an empty metal cavity, I know these > can easily be calculated analytically but I would like to confirm I'm > operating meep correctly before I move onto a more complicated model. > The ctl file for my model is attached to the end of this email and I'm > wondering if I have specified the geometry correctly. I have placed a > cylinder of air inside a cylinder of metal. I assume the thickness of > the perfect metal shield does not matter as meep sets the E field to > zero at the boundary interface?
Yes, as long as the metal is over a pixel thick. > I would like to place a point source at the centre of the cavity in > order to excite the TM modes, my base unit of distance is 1 cm so my > Gaussian source has a centre frequency of roughly 5GHz and a bandwidth > of 3GHz. You are putting an Ez point source at the origin. This is an error. You are specifying m=4, i.e. so that the fields go as exp(4i theta) azimuthally. For this case (and for any nonzero m) the Ez field is zero at r=0 for all modes (TM as well as TE). You need to put your source at a nonzero radius. (You may be getting a nonzero field, but if so it is only because of the discretization and rounding errors.) > When i run the simulation I can't make much sense of the png output for > the dielectric function, does meep output the rz plane when in > cylindrical co-ordinates Yes. > and is > it possible to show the r theta plane? No. Well, you could read the field into Matlab or something and then compute an r-theta plane manually if you wish --- you have all of the information you need because the theta dependence is specified analytically. > When working in cylindrical co- ordinates are centre values specified as > r,theta,z and if so does 0,0,0 represent the centre of the base of the > cylinder or the geometric centre of the object. You specified your cylinder to have "(center 0 0 0)" which means that the geometric center of the cylinder is at the origin. Regards, Steven G. Johnson _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
