The solution for epsilon and mu diverges using short circuit line method at higher frequencies. I have taken a sample material with epsilon=5 and mu=3 of thickness 1.5mm. TE10 mode is propagating in the waveguide.
Using short circuit line method(placing short at d=0 and (d=lamda/4)- reflection data at two positions in a x-band waveguide was retrieved.
From that epsilon and mu were computed. But the results are complying at higher frequencies. The results are diverging especially after(lamda/2) ie 12 GHz. Till (lamda/4) ie 10 GHz results are good enough.
Are there any papers in which the problems in characterization using short circuit line method at higher frequencies is being targeted? Please help.
Hi there, Bhavna.
The work of James Baker-Jarvis (from the National Insitiute of Standards and Technology in the US) and colleagues have published a number of papers on this topic, in particular, addressing the diverging solution issue when the thickness of the sample gets close to an integer number of half-wavelengths thick. This is a common and well known problem with these kind of measurements.
I've listed one reference below which deals with permittivity & permeability determination. It would also be worth searching for other papers by these authors, I think.
"A nonlinear least-squares solution with causality constraints applied to transmission line permittivity and permeability determination", IEEE Transactions on Instrumentation and Measurement, 1992. Authors: Baker-Jarvis, J.; Geyer, R.G.; Domich, P.D.
Hope this helps.
Good luck!
Ray Simpkin
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