Wideband Folded Reflectarray With Integrated Single-Layer Differential Slot Feed

A wideband folded reflectarray antenna (FRA) is proposed in this letter. The differential slot feed employs a 180° feeding network for in-phase radiation. It is inherently integrated with the main reflector of FRA in a single-layer printed circuit board (PCB). Meanwhile, multiresonance unit is designed to achieve a wide bandwidth and a phase range exceeding 360°. To validate the proposed method, a 40 GHz FRA with an electrical size of 12.4 × 12.4
λ
₀
²
is designed and fabricated. The measurement results show a 10 dB impedance bandwidth of 22.7% and a 3 dB gain bandwidth of 21.6%. Moreover, the maximum gain is 28.6 dBi with aperture efficiency of 39.3%. Compared with the published FRAs using planar integrated feed, the proposed FRA widely expands the impedance and gain bandwidth. It also features low profile, low cost, high aperture efficiency, and easy integration with active front ends.