K-/Ka-Band Shared-Aperture All-Metal Polarizer Based on Ridge Waveguide

A K-/Ka-band shared-aperture polarizer is proposed in this letter. The polarizer converts <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> linear polarization into right-hand circular polarization in the K band and left-hand circular polarization in the Ka band. The shared-aperture property is achieved by integrating the K-band and the Ka-band elements into a uniform structure. The polarizer elements are based on ridge waveguides and parallel plate waveguides, which provide the polarizer with low-loss properties. Together with the independent ridges of the K-band elements and the Ka-band elements, the operation bands of these two types of elements can be manipulated independently. As a result, wide and balanced operation bands of 17.7 GHz to 20.2 GHz and 27.5 GHz to 31.0 GHz are achieved. The axial ratios are below 3 dB, and the losses do not exceed 0.8 dB.