## 3 Resonators: Materials and Geometries
### Material Types  
Resonators typically consist of dielectric and conductive materials whose distinct electromagnetic properties can enhance the performance of antennas, particularly by leveraging their electromagnetic properties. Consequently, different materials allow for distinct modifications in the antenna radiation pattern and adjustments in BW and the scattering parameter \(S_{11}\). Dielectric resonators with a high dielectric constant work as efficient energy storage elements, primarily due to the fringe effect, which allows them to confine electromagnetic energy effectively within their structure. This confinement reduces energy losses and contributes to greater overall efficiency in antenna performance. In contrast, conductive resonators, with their lower dielectric constants, store less energy and instead work as waveguides, introducing electromagnetic characteristics that substantially enhance antenna performance [4; 19; 29]. In this study, we evaluate the specific impacts of resonators on the performance characteristics of patch antennas when distilled water, glycerin, and graphite are used as a material. These materials are interesting because they offer distinct properties that benefit a wide range of modern antenna designs. * Distilled Water: Distilled water exhibits a high dielectric constant (\(\approx\)80 at 20 \({}^{\circ}\)C), which significantly reduces the wavelength of electromagnetic waves within the substrate. This property enables the design of smaller patch antennas at the same resonant frequency while minimizing fringing fields at the patch edges. When pure, DW has a high loss tangent, resulting in reduced energy dissipation and improved resonator efficiency. Furthermore, DW offers tunable dielectric properties, which can be adjusted by varying its temperature or mixing it with other materials. Its liquid nature provides additional flexibility, allowing dynamic reconfiguration of resonators to meet specific design requirements. This adaptability is particularly advantageous in applications requiring reconfigurable or adaptive antenna systems [29]. However, DW is sensitive to environmental factors such as evaporation and contamination, which can impact its stability and performance over time, and its liquid nature becomes a problem for containment. Overall, it is most suitable for tunable and adaptive patch antennas. * Glycerin: Glycerin has a moderate dielectric constant (\(\approx\)42.5 at 20 \({}^{\circ}\)C), which reduces the wavelength of electromagnetic waves in the substrate and facilitates the design of compact patch antennas for a given resonant frequency. Its low loss tangent minimizes energy dissipation, thereby enhancing the efficiency of resonators. The polar nature of glycerin, combined with its high viscosity, contributes to stable electromagnetic properties. Its hygroscopic behavior allows it to absorb and retain moisture, which can help maintain consistent dielectric characteristics over time. However, glycerin's dielectric constant is lower than that of DW, limiting its ability to achieve the same level of antenna miniaturization. Its high viscosity can also complicate its use in certain resonator geometries, potentially influencing electromagnetic performance. Despite these challenges, glycerin is well-suited for low-power, reconfigurable, and stable resonators, especially in environments prone to evaporation or rapid temperature changes [30]. Glycerin is more oriented toward stable and low-power resonators in controlled environments. * Graphite: Graphite exhibits a highly anisotropic dielectric constant and loss tangent, with its properties differing significantly between its basal plane and the direction perpendicular to it. In the basal plane, the dielectric constant ranges from 1 to 5, and the loss tangent varies between 0.1 and 1.0. Perpendicular to the basal plane, the dielectric constant increases to 10-15, with a higher loss tangent of between 0.01 and 0.1.