Experimental Demonstration of Anomalous Refraction with a 3D-Printed Binary Grating

The anomalous refraction of an all-dielectric 3D-printed diffraction grating is experimentally demonstrated in the microwave domain. The dimensions of the binary grating are derived using the coupled wave theory and full wave simulations. A maximum diffraction efficiency of 89% is obtained for a TE polarized incident plane wave impinging the grating at 18 GHz with a 50° elevation angle. This efficiency remains above 50% over a 35° angular bandwidth around 50° in the frequency band 17–20 GHz. Outside this angular range, the device is electro-magnetically transparent. A prototype is fabricated with ABS thermoplastic using a fused-deposition modelling manufacturing technique. The structure is experimentally characterized using a near-field bi-static test bench), and the refractive behaviour is demonstrated.