A 2-Bit Reconfigurable Reflect-Array Antenna Element at Ka-Band

A 2-bit electronically reconfigurable reflect-array (RRA) element, integrated with two PIN diodes, is presented at Ka-band. The element can be adjusted to generate four states for 2-bit phase tuning. A dual-layer miniaturized structure is utilized to reduce the performance sensitivity of the element under obliquely incident waves, which is practical for large-aperture beam scanning applications. As a result, a 2-bit phase-shifting is achieved with a phase difference of $90^{\mathrm{o}}\pm 20^{0}$ from 25.8 GHz to 26.3 GHz, possessing an averaged element loss of less than 0.9 dB. The RRA element is fabricated and measured based on the waveguide simulator. The good agreement between the measured and simulated results verifies the proposed design.