30 GHz Electronically Steerable Antennas Using BaxSr1−xTiO3-Based Room-Temperature Phase Shifters

We report the performance of 16-element phased array antennas operating at 30 GHz and ambient temperature. These antennas use BaxSr1−xTiO3(BST)-based phase shifters to produce the beam steering. Ferroelectric phase shifters offer advantages over current semiconductor and ferrite devices including faster switching speeds and lower costs. Also, ferroelectric phase shifters offer higher power handling capability than semiconductor devices and also have high radiation resistance. We made phase shifters from laser-ablated epitaxial BST films as well as from polycrystalline BST-oxide composite films. Although neither the devices nor the materials themselves are fully optimized, phase shifters have shown > 360° of phase shift with < 350 V DC bias (E < 9 V/µm) and ∼8 dB insertion loss. With ferroelectric phase shifters incorporated, antennas show radiation patterns with central-lobe half-power widths of ∼13° and side lobe intensities down by more than 10 dB. Using the phase shifters, the central lobe can be shifted, or “steered,” by ±18° in either direction. These results demonstrate a first step toward a prototype steerable antenna for 20–30 GHz satellite communications as well as other applications.