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SATCOM Reflectarrays

 

Reflectarrays are a type of antenna that combine features from both parabolic reflectors and phased array antennas. Due to their large and easily shaped aperture, parabolic reflectors are known for high gain and narrow beamwidths. Parabolic reflectors are also fed using a feed horn to illuminate its aperture. These features make them simple to design and fabricate. As the beam of the antenna is a result of phase compensation from the physically shaped aperture, the antenna must be mechanically moved to steer its beam. Alternatively, phased arrays are planar antennas that integrate phased shifters behind each element so the beam can be electronically steered. The disadvantage is that the complex feed network results in high losses. Reflectarrays are fed like parabolic reflectors and use phased elements for compensation.  

Fig. 2: A patch reflectarray that is 20 wavelengths in diameter with 1256 elements. The resulting beam is normal to the reflectarray with 31 dB of gain.

Due to this reflectarrays can be planar, lightweight, and low profile. The antenna can also have high gain with an electronically scanned beam. Reflectarrays in modern times have proved extremely useful for radar systems, mobile and satellite communications. These features make reflectarrays an excellent choice for air-born and space applications, including satellite-to-satellite or space-to-earth communication.

The work of our group focuses on designing wideband reflectarray elements, metal-only reflectarray elements, and using novel material for antenna reconfigurability. Reflectarray elements, which are responsible for reradiating the energy of the antenna’s feed horn, previously have been narrowband. This results in lower bandwidth than parabolic reflectors. Reconfigurability allows the beam of the reflectarray to be steered to any direction. Previous reconfigurability methods at millimeter wave frequencies result in high losses.

 

Related Paper

K. Q. Henderson and N. Ghalichechian, “Metal Only Spiral Slot Reflectarray Element Operating at 66 GHz,” 2018 IEEE International Symposium on Antennas and Propagation (APSURSI), Boston, Massachusetts, 2018.