We introduce and demonstrate a ternary nonmechanical beam steering device based on polarization gratings (PGs). Our beam steering device employs multiple stages consisting of combinations of PGs and wave plates, which allows for a unique three-way (ternary) steering design. Ultrahigh efficiency ( $\sim 100\%$ ) and polarization sensitive diffraction of individual PGs allow wide steering angles (among three diffracted orders) with extremely high throughput. We report our successful demonstration of the three-stage beam steerer having a $44°$ field of regard with $1.7°$ resolution at $1550\mathrm{nm}$ wavelength. A substantially high throughput of 78%–83% is observed that is mainly limited by electrode absorption and Fresnel losses.