A one-dimensional electromagnetic band gap (EBG) waveguide phase shifter electronically scanned array (ESA) horn antenna utilizes a linear array of EBG waveguide phase shifters for scanning and radiating a beam. A linear array feed feeds the linear array of EBG waveguide phase shifters. A horn directs radiation from the linear array of EBG waveguide phase shifters. Each of the EBG waveguide phase shifters is a waveguide with vertical and horizontal sidewalls. EBG devices are located on the vertical waveguide walls to shift phase to scan the beam.