# Specific Resonant Properties of Non-Symmetrical Microwave Antennas
## 3 Results and Discussion
### Resonance Properties of Measured Classical Cylindrical Antennas
Figure 9: Change of position of resonance points \(l/\lambda_{res}\) of cylindrical antennas when changing the slimness coefficient \(\Omega\): (**a**) Resonance points of very thin antennas \(\phi=5\) mm; (**b**) Resonance points of medium-thick antennas \(\phi=10\) mm; (**c**) resonance points of very thick antennas \(\phi=30\) mm. From the analysis of Figure 9, we can see that by reducing the length of the antenna its resonant ratio \(l/\lambda_{res}\) (resonant frequency) is shifted to a lower value. By subsequently increasing the cross-section of the small antennas (20 mm), their resonant ratio \(l/\lambda_{res}\) (resonant frequency) shifts to an even lower value. In the case of the whole measured set of 18 cylindrical antennas, the position of the resonant points ranges from a maximum of 0.245 to a minimum of 0.181, which represents the total extent of their change of 0.064 (dimensionless number). This fact is generally known in the theory of antennas and is used in antenna technology in the design of antennas. The effect of the change in the slimness of the cylindrical antenna (in the form of a change in the diameter of the conductor) with a constant height on the position of the resonant point can be generalized from Figure 9. It is also possible to observe the effect of altering the slimness of the cylindrical antenna (by changing the height of the conductor) with a constant diameter of the position of the resonance point. This fact can be assessed in the following Table 2.  
For the characteristic course of changing the position of the resonant points of the whole set of classical cylindrical antennas, it is possible to emphasize the problem of frequency band coverage. The whole set consists of 18 measured antennas. These are divided according to the diameter of the conductor into three sets, each of six antennas. In terms of the frequency range, we consider only the values of the resonant points for the two \"edge\" (coarsest and thinnest) antennas, in each set:  
1. Set of antennas \(\phi=6\) mm Figure 9a 0.245-0.196 = 0.049
2. Set of antennas \(\phi=12\) mm Figure 9b 0.233-0.189 = 0.044
3. Set of antennas \(\phi=25\) mm Figure 9c 0.222-0.181 = 0.041  
Although the values of the difference of the resonance point \(\Delta\) (\(l/\lambda_{res}\)) of classical cylindrical antennas differ (0.049, 0.044, 0.041), the differences according to the conductor diameter are not very significant. The total difference in the values of the resonant points of the whole set of cylindrical antennas is relatively small and is 0.064. For simplicity of illustration and clarity of the explanation of the problem in Figure 9, every graph shows the changes in the position of the points of the resonant ratio \(l/\lambda_{res}\), but only for three antennas. This simplification gives the impression that the resonant points of antennas is based on known knowledge of antenna theory only. However, with this form of imaging, but using a larger number of resonant points of the antennas, as is found with non-cylindrical antennas, the images become more complex, confusing, and harder to interpret. Therefore, another non-traditional form of displaying a larger number of resonant points of antennas was chosen (Figure 10). In Figure 10, 18 resonant points are shown, distributed according to the value of the \(l/\lambda_{res}\) ratio, taking into account the length and diameter of the antenna. This explains the essence of the issue addressed in this article. Diagrams like that in Figure 9 show a concentrated distribution of resonant points, based on existing knowledge of antenna theory. However, the form of distribution of resonant points used in Figure 10 will allow us to better understand the unknown specific properties (differences) between the theory of flat microwave antennas from the theory of classical cylindrical antennas.