# GUI for Analysis of Parameters, Accurate Design and Optimization of Microstrip Filters
## 6 Results and Discussion
### Filter Analysis with MicroStripOptim
This button runs a simulation to obtain data like \(TL\), \(\max(L_{A})\), \(\max(L_{A}^{\prime})\), by sweeping values of \(W_{\rm C}\) and \(W_{L}\), where the minimum and maximum values, as well as the step increments, are indicated in the edit-boxes at the  
Figure 11: Limit width values for \(W_{C}\) and \(W_{L}\) versus \(Z_{0}\). This figure is used to analyze how the limits of \(W_{\rm C}\) and \(W_{L}\) vary for different values of input impedance (\(Z_{0}\)) and relative dielectric constant (\(\varepsilon_{r}\)). A high value of \(\varepsilon_{r}\) could render the filter unfeasible, as it significantly reduces the upper limit for \(W_{Lmax}\). Figure 12: Total length versus \(f_{c}\). The total length is obtained for \(f_{c}\) in a rank from 0.5 to 5 GHz. The discontinuous leaps are due to the fact that the length \(l_{Z0}\), from Equation (19), changes according to the criterion discussed in Section 4.1.  
bottom of the GUI. These plots are important for analyzing the effect of the widths \(W_{C}\) and \(W_{L}\) in the \(TL\) or the maximum attenuation of the filter. The parameters of the filter are taken from the data on the top of the GUI, but \(W_{C}\) and \(W_{L}\) are swept as mentioned. In this sense, one simulation will give results for one specific filter type and order, while for another type of filter, or order, etc., a new simulation must be run. After one simulation is executed, the next two buttons are enabled. The first of them is \"\(TL\), \(L_{A}\), \(L_{A}^{\prime}\)\". The function of this button is to lay out 3D-plots, where the first two axes are \(W_{L}\) and \(W_{C}\), while the third axis, the height of the plot, indicates the variable of \(TL\), \(\max(L_{A})\) or \(\max(L_{A}^{\prime})\), respectively. Figure 13 shows the plot of (a) total length, (b) \(\max(L_{A})\) and (c) \(\max(L_{A}^{\prime})\), for a range of values of \(W_{L}\) and \(W_{C}\). From Figure 13a, it can be noticed that \(TL\) decreases significantly with lower \(W_{L}\) and higher \(W_{C}\). On the other hand, from Figure 13b,c, it can be seen that a low value for \(\max(L_{A})\), and \(\max(L_{A}^{\prime})\) occurs with minimum values for \(W_{C}\), and with medium or higher values of \(W_{C}\), these two parameters increases with lower values of \(W_{L}\). From these three plots, one can conclude that for a low value of \(W_{L}\) and a high value of \(W_{C}\), the length of the filter will be lower, and the parameter \(\max(L_{A})\) will be higher. Finally, the last button, \"TL const\", takes the value from the edit-box \"TL const\" at the bottom of the GUI, in order to trace a 3D surface of \(TL\) versus \(W_{C}\) and \(W_{L}\), previously obtained with the simulation, then, the above surface is overlapped with another surface corresponding to the constant \(TL\). The points where the surface of constant \(TL\) intersects with the \(TL\) surface, form a curve with the values of \(W_{C}\) and \(W_{L}\) that yield a filter of length equal to \(TL\) const. Figure 14 shows the surfaces of \(TL\) and \(TL\) constant, as well as the curve of intersection points between the two surfaces. In this case, \(TL\) constant is set to 78 mm..  
Figure 13: These graphs, generated after the simulation, show the values of certain parameters obtained after designing each filter, varying from \(W_{Lmin}\), \(W_{Cmin}\) to \(W_{Lmax}\), \(W_{Cmax}\). (**a**) Total length, (**b**) \(\max(L_{A})\) and (**c**) \(\max(L_{A}^{\prime})\). With a simple glance at these graphs, it is possible to choose a value of \(W_{C}\) and \(W_{L}\) to achieve a desired value for one of the output parameters. In addition to the plot of Figure 14, three more figures are displayed, with four subplots each one. The three figures correspond to the points that satisfy the constant length constraint, versus its corresponding value of: (a) total width, (b) maximum attenuation, \(\max(L_{A})\), and c) maximum attenuation rate, \(\max(L_{A}^{\prime})\).