## 2 Hybrid Cylindrical DRA over Modified Minkowski-Shaped Metasurface  
The proposed wideband circularly polarized DRA configuration consists of a cylindrical DR of height (D\({}_{\text{h}}\)) 10.16 mm and diameter (Dr) 15 mm. It is designed with a Rogers RT/Duroid 6010 (\(\epsilon_{r}\) = 10.2, tan\(\delta\) = 0.001) and a dielectric substrate of Rogers RT/Duroid 5880 (S\({}_{\text{h}}\) = 3.2 mm, \(\epsilon_{r}\) = 2.2, tan\(\delta\) = 0.001). A metasurface with a 7 \(\times\) 7 unit cell array is designed with a ground plane size of 54 mm \(\times\) 75 mm. DRA is placed over the metasurface, which consists of unsymmetrical rectangular Minkowski-shaped unit cells with a size of X \(\times\) Y = 8.5 \(\times\) 6 mm\({}^{2}\). The distance between the unit cells in the 'x' direction is 1.4 mm, and the distance between unit cells in the 'y' direction is 1.6 mm in the 7 \(\times\) 7 unit\(-\)cells configuration-based metasurface. This non\(-\)uniform arrangement of the rectangular Minkowski-shaped unit cells is responsible for CP radiation, unlike the case of a DR antenna without a metasurface. A coaxial feed location from the center of the cylindrical DR along the diagonal line direction, i.e., \((-\text{Dr}/2,-\text{Dr}/2)\), is optimized for impedance matching to offer a wideband circularly polarized radiation. This HDRA\(-\)1 over a metasurface uses a dielectric resonator as the main radiating element and a metasurface as a reflector to enhance the antenna performance. The dielectric resonator antenna provides a wideband operation; the metasurface, feed location, and the diameter of the DR element are responsible for CP radiation. The dielectric resonator antenna and metasurface combination in Figure 1 lead to a compact and efficient antenna design, which is attractive for various data\(-\)link and wireless LAN applications.  
Researchers have used rectangular and square-shaped metasurfaces in the past, but their narrow band response limited their use. The possibility of a broadband reaction makes a Minkowski\(-\)shaped metasurface an ideal candidate here. It is recommended that a unit cell have a reflection phase response (\(\pm\)90\({}^{\circ}\)) surpassing the frequency range required by the metasurface design. Figure 2 demonstrates the investigation of the reflection phase analysis of the proposed metasurface. The reflection phase at zero degrees is located at 4.85 GHz, with the reflection-phase bandwidth (\(\pm\)90\({}^{\circ}\)) offered from 4.2 to 5.55 GHz, indicating the wideband response of the proposed modified Minkowski metasurface. Metasurface unit cells are spaced by 1.4 mm and 1.6 mm in the normal and azimuth planes.  
Figure 1: (**a**) Top view, (**b**) side view of proposed HCDRA-1 configuration.  
Figure 2: Reflection phase curve of modified Minkowski unit\(-\)cell (given in inset) metasurface.  
A cylindrical DR is optimized for broadband CP radiation and uses a coaxial feed located along the diagonal of the substrate. The distributions of the electric fields are examined and visualized to gain a better understanding of the CP wave generation phenomenon. The magnitude of the E-field in Figure 3 illustrates four time-dependent field distributions (\(\theta\) = 0\({}^{\circ}\), 45\({}^{\circ}\), 90\({}^{\circ}\), and 135\({}^{\circ}\)) for the DRA at 5.0 GHz. From the DR with a metasurface, we can observe the circular rotation of these fields, which suggests a CP radiation for the proposed DRA. This attains the amplitude and phase shift requirements for orthogonal modes of CP radiation. In addition, the clockwise rotation of the electric fields is evident in Figure 3, which indicates it is a left-hand circularly polarized antenna. To avoid any deterioration of the results due to contact between the coaxial feed and unit cells, the metallic part around the feed location is removed with a radius of 2.5 mm.