Numerical Design and Experimental Validation of a Plastic 3D-Printed Waveguide Antenna for Shallow Object Microwave Imaging

Microwave imaging of shallow buried objects has been demonstrated with holographic radar for landmine detection, civil engineering and cultural heritage. A key component of this system is the antenna based on a truncated cylindrical waveguide with two feeds. This paper investigates for the first time a manufacturing technology based on the 3D printing of a volumetric cylindrical plastic antenna. The investigation of this manufacturing technology was motivated by the reduction in the antenna size and customization of the electromagnetic characteristics to the radio frequency electronics mounted on the robotic scanning system. The antenna that was designed using a simulator and filled with polylactic acid plastic material (relative dielectric permittivity Ɛr = 2.5) is compared to the metal antenna, both operating at around 2 GHz. The goal was to replicate the characteristics of the void core antenna to be able to provide the same quality/information of the microwave images of shallow buried objects. Finally, we compared the scan results of dielectric and metal targets both in the air and in natural soil. From the observation of some of the characteristics of the images, such as dynamics, morphology of the target, signal-to-noise ratio, and operating distance, we demonstrate that 3D printing for volumetric cylindrical waveguide antenna could be used to obtain compact and easily adaptable antennas for different applications in remote sensing.