An X-band Portable 3D-printed Lens Antenna with Integrated Waveguide Feed for Microwave Imaging

This paper presents a portable 3D-printed lens antenna fed by a standard rectangular waveguide at X-band for object classification. The proposed lens antenna can integrate with the standard rectangular waveguide without any additional assistant tools. A high impact polystyrene is used to design the 3D-printed hemispherical lens antenna by using the fused deposition modelling technique. This additive manufacturing gives several advantages including rapid prototyping, better cost and time effectiveness. Five lens radiuses, e.g., 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm, are investigated to increase the gain of the antenna. The optimum dielectric tapered transition dimensions are simulated and obtained by using the 3D EM Simulation tool CST Studio, resulting in the reflection coefficient (S
₁₁
) of five lens antennas better than -10 dB across the WR-90 band. From the simulation results, the lens radiuses of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm, provide the average realized gain of 12.9 dBi, 15.2 dBi, 16.7 dBi, 17.7 dBi, and 18.6 dBi, respectively. To confirm the antenna performances of the proposed design, two lens radiuses, e.g., 20 mm and 30 mm are selected to fabricate. The gains of the lens radius of 20 mm and 30 mm are 12.1 dBi, and 14.2 dBi, respectively. The half-power beamwidth (HPBW) of lens radius of 20 mm and 30 mm are approximately 35° and 24°, respectively. The proposed dielectric lens antenna also offers other advantages, such as ease of design, low fabrication and material cost, and ease of mount and un-mount with WR-90 waveguide flange. Moreover, the narrow HPBW of lens antenna fed by standard waveguide can be applied to improve the resolution of the imaging system.