A Reflectarray Antenna Based on Diamond-Ring Slotted Elements With Enhanced Reflection Phase

This paper presents the design and investigation of a reflectarray antenna with diamond-ring slotted elements operating at a frequency of 20 GHz. The diamond-ring slot applied to the design can extend the reflection phase range of the unit-cell. The reflectarray antenna has a dimension of 190 × 190 mm ² with a total of 505 elements in a circular aperture and a focus of 150 mm. A rectangular horn antenna with a symmetric beamwidth of 35° and 14.4 dBi gain is proposed as the antenna feed. The designed antenna has improved gain with a value of 27.2 dBi directed to $\bm{ (\theta = 0^{\circ}, \phi=0^{\circ})}$ and a 5.8° beamwidth.