Abstract: The signal polarization rotator of this invention utilizes a rotatable signal transition structure having one section which acts as a coaxial transmission line center conductor, a section suspended over a first ground plane, a section above a second ground plane, the latter section varying in distance from the ground plane in an exponential, exponential like or linear taper, and optionally an extended section which in the preferred embodiment is used because of waveguide dimensions and acts as approximately a one quarter wavelength gap radiator and a section coupled to the coaxial center conductor and the gap radiator.