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Re: calculation of dielectric loss

 --Previous Message--: hi, : i have problem regarding calculating the dielectric loss. i have a : ceramic disc of 3mm and 45mm dia having dielectric constant 10 and loss : tangent 0.0003. Microwave power of 24kw is passing through it at a : frequency of 2.856 GHz. Please inform me the mathematics to calculate the : dielectric loss in the ceramic. : raju : Hello Raju,I have comparatively little experience with microwave engineering, but I'll try to provide some starting points. The estimated power (in watts/cubic cm) that will be converted to heat within the dielectric due to losses can be estimated as: Pd = (55.61*10^-14*)*(Ed^2)*f*Er*tan(d)where: Pd = watts/cm^3 Ed = field strength in volts/cm within the dielectric f = frequency (in hertz) = 2.856*10^9 Er = relative dielectric constant = 10 tan(d) = 0.0003A simple plane, sinusoidal, TEM wave in free space (Zo = 377 ohms) will have an average E field (Eo) of: Eo = Sqrt(P*377)where P = watts/meter^2. The E field within the dielectric (Ed) will be about 1/10 of Eo because of the ceramic material's relatively high dielectric constant. However, it's quite unlikely that you have this simple of a case in reality. Finally, the total power in watts absorbed by your dielectric slab will be: W = Pd*V where: V = the volume of your particular dielectric slab = 0.3*Pi*(4.5/2)^2 = 4.77 cm^3 IN reality, the actual distribution of the electric field within the dielectric is most likely quite non-uniform and, as a result, you'll develop a number of "hot spots" wherever the E-field is more intense. A more exact solution will require using field solver/modelling software. Here are some sources of information you may find helpful:http://www.pueschner.com/engl/pdfs/basics_adv_en.pdfhttp://www.pueschner.com/engl/pdfs/MicrowaveHeating.pdfhttp://rpaulsingh.com/teaching/LectureHandouts/microwave_handout.pdfHope this helped and best regards,Bert Message Thread influence of voltage on dielectric loss - Tim 3/18/2005, 6:21 am Re: influence of voltage on dielectric loss - Bert Hickman 3/18/2005, 5:49 pm calculation of dielectric loss - Raju Manna 7/13/2006, 1:52 am Re: calculation of dielectric loss - Bert Hickman 7/13/2006, 3:46 pm « Back to index | View thread » 