Electronically Reconfigurable Filtering Reflectarray Antenna Using Polarization Conversion Elements With Controllable Conversion Zeros

This communication introduces an electronically reconfigurable filtering reflectarray antenna (RFRA) with good frequency selectivity and wide beam-scanning angle. The proposed reconfigurable element consists of a metal ring loading two positive-intrinsic-negative (p-i-n) diodes at the ring openings, a patch with a complementary split ring, an E-shaped patch, a ground plate, and the dc biasing network for p-i-n diodes, which can not only convert the y-polarized incident wave into the x-polarized reflected wave, but also offer a 1-bit reflection phase. Furthermore, the proposed element can generate two controllable conversion zeros to permit high-selectivity filtering performance and adjustable bandwidth. A RFRA with $40\times 40$ elements is analyzed in detail to demonstrate the filtering and beam-scanning capabilities, whose realized gain can reach 26.4 dBi at 29 GHz with an aperture efficiency (AE) of 15.7% and beam scanning angle can reach 60°. For lab-level verification, a $10\times 10$ RFRA prototype has been fabricated and measured. The measurement and simulation results align well with each other, demonstrating that the proposed RFRA has good frequency selectivity and wide beam-scanning capabilities.