Substrate integrated waveguide (SIW) technology that combines 3D and 2D structures has been successfully utilized due to its notable advantages, including in its application to H-plane horn antennas. As this type of antenna is commonly constructed on thin substrates, the E-plane radiation pattern is always wide, thereby limiting the achievable gain performance. In this work, we propose an approach that incorporates 3D printed horns on a prefabricated SIW H-plane horn antenna to successfully narrow the E-plane radiation pattern, thereby improving the gain performance. The proposed E-plane horn is designed at the aperture of the original H-plane horn, providing a smooth and continuous wave transition from the thin substrate to the end-fire direction. This approach improves the directional radiation performance significantly and reduces fabrication time and associated difficulties as the parasitic structures are simply attached to the SIW horn, without the requirement of redesigning or refabricating the original antenna. From 20 to 25 GHz, an optimized prototype shows excellent performance. At 22.7 GHz, it exhibits 35° and 33° for the E- and H-plane half-power beamwidths (HPBWs), with corresponding side-lobe levels (SLLs) of −23 dB and −15 dB. The present research reveals that the proposed design presents high feasibility and a reduced demand for high-precision manufacturing processes at a lower cost, concomitantly providing an effective means to further improve on the radiation characteristics.
Increasing Mechanical Properties of 3D Printed Samples by Direct Metal Laser Sintering Using Heat Treatment Process