A novel wideband reflectarray antenna (RA) is designed for 5G millimeter (mm) wave communications in the frequency range of 26.5–36 GHz. The proposed unit cell is constructed using a grid periodicity of 0.52${{\lambda }_0}{ }$ that offers 636° phase change through phase delay lines (PDLs) (${{\theta }_{\text{s}}}$). These PDLs are attached to the outer end of the unit cell comprising semi-circular rings. Bandwidth enhancement is achieved by incorporating a corrugated slot technique and a suitable air gap beneath the substrate. The proposed center-fed reflectarray is composed of 513 elements distributed in a circular aperture (13.46${{\lambda }_0}$). Using mirror-symmetrical distribution of the unit cells, a cross-polarization reduction as low as −50 dB is realized. At 30 GHz, RA has a measured peak gain of 28.2 dBi, a sidelobe level of −14.3 dB, and an aperture efficiency of 31.4%. The prototype antenna is fabricated, and the simulation results are experimentally validated. The measured 1-dB and 3-dB gain bandwidths of the proposed reflectarray antenna are 31.3% and 41.6%, respectively. The proposed broadband reflectarray can be a potential choice for inter-satellite services like inter-satellite networking/satellite positioning and control; fixed satellite services such as GPS satellite synchronization and data direct to home TV; and satellite position fixing.

This paper investigates the performance of 3D-printed dielectric reflectarray antennas (RAs) with wideband behavior and beam-steering capabilities. The designed unit cell consists of a single-layer dielectric element perforated with a square hole, whose side is used to control the local variation of the reflection coefficient. The numerical analysis of the unit cell and of first $52\times52$ reflectarray working in Ka-band, whose scanning capabilities are tested just moving the feed along an arc, confirms that the unit cell has a stable behavior with respect to both the frequency and the direction of arrival of the incident field. In view of these promising capabilities, the proposed unit cell is used to design a bifocal reflectarray with the same size and working in the same frequency band of the first one. Its numerical characterization and the measurements of a prototype prove that the RA is able to provide less than 0.8 dB of gain losses over a scanning range of ±40∘ in the vertical plane, while the bandwidth varies between 13.5% and 28%, depending on the pointing direction. The obtained results demonstrate the effectiveness of the proposed approach and highlight the potential of 3D-printing technology for producing high performance, cost-effective RAs with wideband behavior and excellent beam-steering features.

This contribution describes the design and simulations of a multibeam 1.8 m parabolic reflectarray antenna for geostationary high throughput satellites (HTS) in Ka-band. The parabolic reflectarray generates two orthogonal circularly polarized beams per feed simultaneously at 19.7 and 29.5 GHz, by the variable rotation technique. The antenna is made of 62 654 reflectarray cells, which include two types of printed elements independently rotated and adjusted. The elements have been optimized one by one to ensure the required phase-shift at each frequency. A novel design approach has made it possible to promptly obtain an initial layout of every element with a very low computational cost. The simulated radiation patterns show that the parabolic reflectarray, illuminated by 27 dual-circularly polarized feeds, can generate 54 spot-beams in two orthogonal polarizations, with a beam spacing of 0.56° between adjacent beams. The design and simulation tools have been validated by a parabolic reflectarray scaled in a factor of 0.5, which has been manufactured and tested. The proposed reflectarray would allow to generate a complete multi-spot coverage from a geostationary HTS with only two parabolic reflectarrays, instead of four reflector antennas, also reducing the number of feeds by half, since every feed generates two beams.