Toward High-Power Beam-Steerable Reflectarrays Using Tunable-Height Dielectric

Abstract

A novel method for a high-power reconfigurable reflectarray (RRA) with a moderate 30° beam scanning is demonstrated. The proposed technique eliminates the need for mechanical steering of reflectors for satellite communication. A small mechanical movement of a patterned dielectric structure under multislot elements achieves beam steering by changing the coupling. Due to the unique shape of the multislot element, the unit cell is capable of tuning the phase for both linear polarization and circular polarization (CP) within a single design operating at 20 GHz. The maximum phase range obtained in this design is a continuous 280° for RHCP, LHCP, and two linear polarizations at 20 GHz. The phase of the reconfigurable unit cell is verified and measured using a waveguide simulator attached to a micromotor. Maximum element loss is simulated to be 0.5 dB. To demonstrate beam steering, three reflectarrays with frozen dielectrics and square array lattices composed of 400 elements ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\lambda _{0}\,\,\times 10\lambda _{0}$ </tex-math></inline-formula> ) are fabricated. The frozen reflectarrays demonstrate beams at 0°, 15°, and 30°. The measured gain is found to be 23.2 dB at broadside with 21.8 and 23.3 dB, respectively, when scanned to 15° and 30°. The 1 dB gain bandwidth is measured to be 7.45% with a 3 dB axial ratio bandwidth of 12.1%. Unlike other architectures that use nonlinear semiconductor devices, the proposed reflectarray uses a dielectric insert with a height that can be controlled by a micromotor suitable for high-power applications supporting up to 80 MW/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{2}$ </tex-math></inline-formula> .