Computer Simulation Technology (CST) is a commercial microwave software tool used in the simulations and design of electromagnetic structures. The problem that usually found in CST design simulation is time consuming during the process and at end the results might not be good as expected. First of all before the start of the simulation process identical SRR loaded rectangular waveguide was drawn and various design configurations were generated.
The simulations of metamaterial element loaded waveguide structures are really timed consuming but previous authors have not paid much attention to this problem. My thesis work investigated a way of improving this problem to address long time consumption. Under the boundary conditions symmetry planes have set in particular directions; all to none field directions which involves all cases of fields, all to electric (electric fields are anti-symmetric whilst the magnetic fields are symmetric) or magnetic field directions (magnetic fields are anti-symmetric whilst the electric fields are anti-symmetric), one of the symmetry planes XZ plane electric or YZ plane magnetic or vice versa. The figure 3.11 below show the directions of symmetry planes under the boundary condition of CST design configuration structures.
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Figure 3.11 Setting of symmetry planes under boundary conditions.
The first approach was setting all symmetry planes XZ and YZ to none fields directions and the simulation process took longer hours (total of 9 hours, 35mins and 55sec) but the modal pass-band appeared on the dispersion graphs. This way of setting the symmetry planes thought exhibited backward wave mode as expected but was unable to produce a fast enough simulation process. In the same design all symmetry planes XZ and YZ were set to electric fields directions the simulation was faster (total of 6 hours, 28mins and 14sec) consequently obtaining modal pass-band below the cutoff frequency. This approach of symmetry planes setting to all electric directions does not only speedy up the time but also exhibit modal pass-band. The other two settings of the symmetry planes was also fast enough but backward wave modes could not appear on the dispersion graphs.
Estimated numerical results
The numerical values (Bandwidth, Center frequency and Cutoff frequency) estimated from the dispersion diagrams due to the effects of various waveguide parameters and configurations are presented. The dispersion diagrams are the results performed by the computer simulations of the structure using CST Microwave Studio. The estimated values are tabulated according to the heights of the waveguide, 14.5mm, 15.25mm and 16mm.
Table 3.5 Height = 14.5mm
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6.19 0.54 2.03 5.82 0.017
6.54 0.57 1.93 5.58 0.017
Figure 3.12Bandwidth versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.5 shows height, Bandwidth and SRRs dimensions. The height of the waveguide is 14.5 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 3.98mm 6.8mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
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Figure 3.13 Center frequencies inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.5 shows height, Center frequency and SRRs dimensions. The height of the waveguide is 14.5 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 3.98mm 6.8mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
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Figure 3.14Cutoff frequencies versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.5 shows height, Cutoff frequencies and SRRs dimensions. The height of the waveguide is 14.5 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 3.98mm 6.8mm8, 0.55
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5.4328125 0.47 2.05645 5.76 0.0151
5.795 0.51 2.0164 5.7 0.0151
6.1571875 0.54 1.97325 5.63 0.0155
6.519375 0.57 1.93605 5.58 0.0159
6.8815625 0.60 1.84425 5.345 0.0155
Figure 3.15 Bandwidth versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.6 shows height, bandwidth and SRRs dimensions. The height of the waveguide is 15.25 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 4.19mm 7.24mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
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Figure 3.16 Center frequencies versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.6 shows height, Center frequencies and SRRs dimensions. The height of the waveguide is 15.25 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 4.19mm 7.24mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
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Figure 3.17 Cutoff frequencies versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.6 shows height, Cutoff frequencies and SRRs dimensions. The height of the waveguide is 15.25 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 4.19mm 7.24mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
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6.12 0.53 1.98 5.665 0.016
6.48 0.56 1.95 5.63 0.015
6.84 0.6 1.85 5.38 0.014
7.6
4.18 0.36 1.97 5.28 0.0017
4.56 0.4 1.92 5.26 0.003
4.94 0.43 1.86 5.21 0.007
5.32 0.46 1.8 5.17 0.005
5.7 0.5 1.76 5.13 0.005
6.08 0.53 1.7 5.07 0.005
6.46 0.56 1.65 5.02 0.005
6.84 0.6 1.6 5.01 0.005
7.22 0.63 1.51 4.87 0.005
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Figure 3.18 Bandwidth versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.7 shows height, bandwidth and SRRs dimensions. The height of the waveguide is 16 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 4.4mm 7.6mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
Figure 3.19 Center frequencies versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.7 shows height, Center frequencies and SRRs dimensions. The height of the waveguide is 16 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 4.4mm .6mm8, 0.55
0.95, 0.55 0.087rad 0.087rad
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Figure 3.20 cutoff frequencies versus inner radius. Each of the nine outer radii has nine varying inner radii
Table 3.7 shows height, Cutoff frequencies and SRRs dimensions. The height of the waveguide is 16 mm and its width is 35 mm. The relative permittivity of each of the two dielectric side slabs is 4.5 with thickness 1.55mm. 4.4mm 7.6mm8, 0.55
0.95, 0.55 0.087rad 0.087rad