In general dielectric constant decreases with increase in frequency but in some cases at higher frequencies (above 10^5 Hz) we can observe there is a marginal increment in dielectric constant at higher frequency..what might be the reason for increase in dielectric constant
Dear Abhinay Sreeram,
Two reasons are possible.
1) Material under test can exhibit Maxwell-Wagner type polarization at
this frequency range.
2) More probably differences in results may be related to the uncertainty of measurements.
I wonder what was the method of your measurements? If it was lumped element method (capacitor) then the presence of parasitic elements would cause discrepancy in the final results.
Thank you Jerzy Antoni Krupka sir for sharing your knowledge..measurement was done for pellet sample using solartron equipment at room temperature....
I think the dielectric constant remains that same but when you move to such high frequencies, your capacitor may not get enough time to fully charge. Since, the tools you use to find capacitance are actually looking at the time required to charge a capacitor. At higher frequencies, before the capacitor can get fully charged, the charging time is taken by the tool. Smaller 't' means larger 'C' resulting in a higher dielectric constant.
I am not 100% sure, but I think it is the limitation of the experimental setup, and not related to the material itself. In order to verify, you can keep increasing the frequency and if you keep seeing a linear increase in dielectric constant then I may be right. Hope I was of some help. Good luck.
We observed this dependence behavior. Maybe this work will help you.
Article Further refinements to the waveguides materials measurements...
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