Discussion Forum

Hello,

I am having trouble finding the dispersion curve for a Sommerfield-Gobau Wire( single wire transmission line).
The model is attached below. It consists of a 2-D geometry with an inner conductor region assigned a dispersive permittivity with real and imaginary components that is surrounded by an outer air region of a much larger radius (i.e., 10*free space wavelength). This air region's outer boundary is assigned a scattering boundary condition. The study is a Mode Analysis with a parametric sweep over frequency. My goal is to obtain the dispersion (i.e, propagation vector in z (beta_z) versus frequency). Before running the large frequency sweep, I try to obtain a few points on the dispersion curve to make sure the simulation is working.

Now, I am trying to build on this previous paper found on arXiv. (arxiv.org/ftp/arxiv/papers/1305/1305.3500.pdf ). Using their exact dimensions and material parameters for the conductor region, I am unable to observe the dispersion of the surface-wave TM01 mode deviating away from the light line to larger beta values (i.e., the slow-wave dispersion region). This can be observed in Fig. 2(a) of that paper. Would anyone be able to check out my simulation model and see where I am going wrong? I have had success with this approach in finding the dispersion of guided waves in enclosed waveguides (i.e., the PEC circular waveguide) that contains dispersive filling materials.