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

Abstract

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.

A 3-D-Printed High-Dielectric Materials-Filled Pyramidal Double-Ridged Horn Antenna for Abdominal Fat Measurement System

“…4, respectively. A thin, flexible and magnetically loaded silicone microwave absorbing material sheet (i.e., ECCOSORB FGM-40) has been selected to be employed as part of the high-performance design of the proposed antenna [34]. The measured dielectric properties of this absorbing sheet have been loaded into the simulation software presented in Figs.…”

Beamformer development challenges for 5G and beyond

“…RF energy focusing AQ8 structures linking Luneburg, spherical, semispherical, gradient dielectric, constant dielectric and Rotman lenses are gaining a lot of attention as fixed beamformers, especially in mmWave spectrum. Primarily due to their focusing capability and ease in manufacturing, they are sometimes preferred over phased-array-based beamformers [39,[81][82][83]. A simple 3D-printed Luneburg lens [82] has been shown to have a gain value of 21.2 dB i.…”

“…Such lenses perform same operation of superimposing the radio signal in a transmission as it happens in a Butler matrix [70]. Recent example of a flexible Rotman lens that can be used for mmWave fixed beamformer application is shown in [83]. The passive lens structure can generate multiple beams at 28 GHz and a switching network performs the beam selection.…”

“…The beam-scanning range in this beamformer is AE39.5 so it is usable in fixed beamforming scenarios. In [83], the Rotman is shown to have a bandwidth of 18-38 GHz. Another Rotman lens example at high frequencies is in [89] in which the lens operating frequency is from 25 to 31 GHz while generating seven beams.…”

A new impedance matching approach for microstrip Rotman lens based on analyzing the standing wave pattern of an electric field

“…Recently, new applications based on the microwave lens on various platforms have been suggested. These include fifth generation (5G) applications, multiple‐input and multiple‐output (MIMO) systems, ultra‐wideband (UWB) radiators, satellite communication, radiofrequency identification (RFID), remote sensing and near‐field focus (NFF) communications, and collision avoidance (CA) for automotive applications …”