Broadband, Reconfigurable Transmit-Reflect - Array (TRA) With 1-Bit Phase Shift and Bidirectional Beam Steering

We presents a broadband, 1-bit reconfigurable transmit-reflect-array (TRA) design that is capable of switching between transmit-array and reflect-array modes to provide bi-directional beam steering. The proposed TRA unit cell uses two positive-intrinsic-negative (PIN) diodes to switch between four operating states to realize 1-bit phase resolution and co-polarized radiation in both the reflection and transmission modes. To provide the same polarization for the backward and forward radiation, the unit cell acts as two cascaded <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">90∘</tex> -polarization rotators in the transmission mode and as a non-polarization-rotation reflector in the reflection mode. Simulation results for the TRA unit cell designed for operation at C-band show an operating bandwidth of 23% for 1-bit transmission and reflection phase shifts. The proposed unit cell was used to construct a TRA consisting of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18 × 18</tex> elements. Full-wave simulation results for the TRA operation at 5 GHz predict a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">± 60∘</tex> scan range and a peak aperture efficiency of 18.5% for the reflect-array mode as well as a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">± 45∘</tex> scan range and a peak aperture efficiency of 12.4% for the transmit-array mode.