A Wideband Low-Profile Reconfigurable Transmitarray Using Magnetoelectric Dipole Elements

A wideband 1-bit reconfigurable transmitarray antenna (RTA) with low-profile characteristic is presented. First, a wideband element for the RTA is designed by combining two centrally-fed magnetoelectric (ME) dipoles. Two PIN diodes are integrated within the element to achieve 1-bit reconfigurable phase states. Next, the folded scheme is adopted to achieve multiple reflections between the feed source and the RTA, thus the height-to-diameter ratio (H/D) is reduced to about one-third of that of the conventional transmitarray. A reflective surface with polarization conversion function is designed beneath the RTA around the source, the unit cell of which is a special C-shaped polarizer operating over a wide frequency band. Finally, a low-profile RTA with 12 × 12 elements is designed, fabricated, and measured. The whole structure has an aperture size of 5.75λ₀ × 5.75λ₀, and the H/D is 0.28. Measured results show that the proposed RTA has the beam-scanning capability to ±40° in both E- and H-planes over a bandwidth of 32%. The realized gain is up to 19 dBi and the peak aperture efficiency is 20.5%.