An Anisotropic 3D Printed Circular Polarization Converter for a Patch Antenna Array Operating in the Ka Band

This paper proposes and evaluates a method for creating circular polarization using a linearly polarized patch antenna array tuned for 30.5 GHz and a low cost anisotropic polarization converting superstrate fabricated by means of additive manufacturing. The polarization converter exhibited a narrow axial ratio bandwidth over frequency with sharp roll off rates. The simulated efficiency and far field performance of this antenna is evaluated, as well as its ease of design and manufacture. This takes the form of an analysis of measured results using the design for a copper etched linearly polarized array and 3D printed polylactic acid (PLA) polarization converting superstrate. This resulted in a highly directive antenna array, expressing directivity of 23.4 dBi and gain of 19.9 dBi. Good circular polarization was observed, with boresight axial ratio of 2.16 dB at the target frequency and a 3 dB axial ratio bandwidth of 900 MHz.