A tunable phase shifter is provided that includes a spatial phase shift element and a conducting sheet. The spatial phase shift element includes a dielectric substrate and a conductive antenna element mounted on the dielectric substrate. The conducting sheet is mounted a distance from the spatial phase shift element and configured to reflect an electromagnetic wave through the spatial phase shift element. The conductive antenna element is configured to radiate a second electromagnetic wave in response to receipt of the reflected electromagnetic wave. The distance between the conducting sheet and the spatial phase shift element can be changed to adjust a phase shift of the reflected electromagnetic wave.