A phase shifter for and a method for shifting phase in an antenna configured to emit a radio signal at a wavelength include a transmission line. The transmission line has a length along a primary axis and a width across a secondary axis. The primary axis and secondary axis intersect to define a waveguide plane. A conductive screen layer has first and second screen surfaces. The screen surfaces are substantially planar and disposed parallel to and spaced apart from the waveguide plane by a distance and are spaced apart from each other by a screen thickness much smaller than a skin depth of the screen layer determined at the wavelength. A dielectric layer envelopes the screen layer and has a first dielectric surface residing substantially in the waveguide plane and a second dielectric surface parallel to and spaced apart from the first dielectric surface by a height greater than the distance. A conductive ground plate has a ground plate surface substantially coplanar with the second dielectric surface whereby the propagation of the signal along the transmission line is slowed by a slowing factor.
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