On the Additive Manufacturing of Conformal Slotted Waveguide Antennas.

We present here the design and 3D-printing of Conformal Slotted Waveguide Antenna Arrays (CSWAA) in Ku-band. These solutions are appealing candidates for applications where 3-D Adaptive Electrically Scanned Array (AESA) antennas are employed in conformal surfaces, like airplanes, for beam-steering. First, a non-optimized antenna with a coaxial to ridged waveguide transition is designed and manufactured in Stereolithography (SLA). Then the antenna is later metallized and measured. The problematic aspects of the complex transition are further optimized by a second highly compact antenna concept which employs a direct coaxial feeding mechanism. The second and optimized CSWAA is fabricated in Selective Laser Melting (SLM) and is verified experimentally. Both numerical and measurement results show a close agreement. The proposed CSWAA presents return losses above 10 dB and realized gain above 14 dBi over a relative bandwidth of 8%.