Broadband circular polarized reflectarray based on multi‐resonance unit

In this paper, a broadband circular polarized (CP) reflectarray using a linear polarized (LP) feed is proposed. First, a single‐layer broadband dual‐line polarized reflectarray unit is designed. This unit converts the LP incident waves into CP reflected waves by providing a phase difference of 90° in the orthogonal direction components of the incident waves. Based on the units proposed, a 109‐element reflectarray was designed and fabricated. The measured results indicate that the reflectarray has a 1‐dB gain bandwidth of 9.15 to 12.79 GHz, or equivalent to a bandwidth of 33.2%. Its 3‐dB axial ratio (AR) bandwidth for CP operation is 37% (9.06‐13.19 GHz). The reflectarray antenna has a peak gain of 23.53 dBi and its highest aperture efficiency is 64.1% achieved at 10 GHz.