A low‐profile 28‐GHz Rotman lens‐fed array beamformer for 5G conformal subsystems

This paper reports on the first demonstration of an experimental millimeter‐wave (mm‐wave) beamforming based on the conformal Rotman lens. The passive switched‐beam network is intended for operation in the 28‐GHz band, covering the 18‐38 GHz range, for the deployment in the fifth generation (5G) subsystems. The primary objective of this work is to conduct the feasibility of designing a beamforming network (BFN) based on the liquid‐crystal polymer substrate, and to evaluate the performances in terms of the scattering (S)‐parameters and surface currents for the proposed flexural case of the convex‐circumferential bending. A prototype has been accurately fabricated, and a setup has also been deployed to conduct the measurements. The performance in terms of the linear progressive phase behavior, as the main figure of merit, has been shown. The BFN exhibits significant characteristics to be used as a low‐profile unit of the transceivers with the in‐built beam steering for the conformal 5G subsystems.