Design of a 5 GHz Reflectarray with Reduced Size Unit Cell and Extremely Low Phase Sensitivity

This article presents a novel, compact reflectarray antenna operating at 5 GHz. The array consists of two types of phasing element - square ring and complementary square ring. The complementary square ring is used for the phase values that are not covered by the single ring element. The grid size of the array is 0.28λ × 0.28λ at operating frequency 5 GHz that is much smaller than the conventional periodicity 0.5λ × 0.5λ. The aim of unit cell design is to have a slower slope of the reflection phase graph without sacrificing the phase range of 360° where in general there is a trade-off between these two goals. The maximum slope in reflection phase graph is obtained here is 34°/mm. The proposed array is fabricated on a low loss PTFE substrate of thickness 3.175 mm (0.053λ at 5 GHz) and illuminated by a horn antenna. Radiation pattern results show a very precised far-field beam with 3-dB beamwidth of 7° and 7.3° for two principle planes respectively. The gain of the antenna is 26 dBi at 5 GHz