3-D-Printed All-Metal Conformal Circularly Polarized Reflectarray Antenna at X-Band

This article presents a proposal for a 3-D-printed all-metal conformal circularly polarized (CP) reflectarray antenna operating in the X-band. The reflectarray element is constructed with a quasi-I-shaped arm with a pillar at the center as support. To enhance the angular stability of the reflection response for oblique incidence, 12 metal blocks are introduced around the element. In addition, a compact wideband 3-D-printed CP horn antenna is designed as the feeding source. A novel method for estimating the aperture efficiency (AE) of the conformal reflectarray is derived to determine the reflection phase distribution of the reflectarray and the position of the feeding antenna. To validate the proposed reflectarray element and approach, an all-metal $15\times15\,\,3$ -D printed conformal reflectarray is designed, fabricated, and measured. The experimental results demonstrate a 42.3% (8.2-12.6 GHz) 3-dB axial ratio (AR) bandwidth, an 11.4% (10.4-11.6 GHz) 1-dB gain bandwidth, a 27% (9.6-12.6 GHz) 3-dB gain bandwidth, and a 40.7% AE.