3-D-Printed High-Gain Millimeter-Wave Horn Antenna With a Hybrid Metal and Dielectric Lens

This article presents a 3-D-printed, broadband, high-gain, dual-polarized horn antenna with a hybrid lens. The proposed hybrid lens combines a slow-wave lens (a dielectric convex lens) with a fast-wave lens (a metal concave lens), which reduces the lens thickness. Moreover, the proposed lens structure theoretically allows for any positive value of the focal length-to-diameter ratio (F/D), ensuring that the lens can operate under a smaller F/D. By reducing the lens thickness and working with a smaller F/D, the overall length of the high-gain horn antenna is significantly shortened. The working principle and design process are provided. To validate the proposed theory, a lens horn antenna operating in the Ka-band with an F/D of 0.6 and a radiation aperture diameter of 80 mm (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\lambda $ </tex-math></inline-formula>@30 GHz) is designed and fabricated. The total length of the antenna is 67 mm (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.7\lambda $ </tex-math></inline-formula>@30 GHz). Test results show that the proposed lens horn antenna covers the entire Ka-band with a −10 dB impedance matching, achieves a peak gain of 26.9 dBi, and a peak aperture efficiency of 65%. The length (axial length) of the proposed lens horn antenna can be reduced to approximately 1/3 of that of an optimized horn antenna. The proposed lens horn antenna, characterized by its compact dimensions, high gain, and high aperture efficiency, is eminently suitable for applications such as millimeter-wave (mmWave) point-to-point communications.