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Abstract The characterization of antenna radiation patterns in millimeter‐wave (mmW) bands can be particularly challenging. Due to a small wavelength, minute misplacement of the probe antenna in the order of few millimeters can generate substantial errors in the measured pattern. A highly precise measurement system that incorporates a 6‐axis compact robotic arm is implemented to overcome this challenge. System testing shows a positional accuracy and repeatability of approximately 20 μm or 0.004λ at 60 GHz. After implementation, programming, and testing, the system is used to measure gain patterns on three different mmW antennas. The radiation pattern of a 50–75 GHz standard gain horn antenna demonstrated the accurate measurement at the far‐field using the robotically controlled system. Furthermore, the characterization of the center element pattern of a 60 GHz phased array has shown that the measurements with this system are repeatable and suitable for arrays as well. Additionally, we performed near‐field measurements by successfully characterizing a 40–60 GHz horn antenna with a planar scan. 

A planar and thin‐grooved Fresnel lens is a great candidate for gain enhancement in millimetre wave communication, imaging systems, and wireless power transfer applications. The authors report the design, fabrication, and measurement of a 3D‐printed Fresnel lens, using a single material. A low‐profile (1.2λthick) 4‐zone Fresnel lens with 16 annular rings is designed with a focal length of 40 mm (≃4λ) operating at 30 GHz. Authors’ design consists of four‐step heights with outer radius of 69 mm (6.9λ). Permittivity and loss tangent of polylactic acid are measured to be 2.79 and 0.0048 at 30 GHz, respectively. Focusing ability of the lens is studied using full‐wave simulation. The lens is fabricated using a table‐top commercial fused deposition modelling printer. The surface roughness, step heights, and radii of each zone are measured and verified using a 3D optical profilometer. Impact of the 3D‐printed limitation on performance of the device is discussed. The gain of the fabricated prototype is measured, in conjunction with a horn antenna, in an anechoic chamber. Pattern measurement results illustrate 6.6 dB gain enhancement at broadside at 30 GHz. Gain enhancing behaviour is studied at three different focal lengths and frequencies of 29–31 GHz.