Time

22.11.2021 kl. 09.30 - 13.00

Description

Title
Millimeter-Wave Transmitarray and Reflectarray Antennas for Communications Systems

Abstract
It is an inevitable trend to investigate and develop millimeter-wave technologies for communications systems as millimeter-wave can provide high data rate, broad channel capacities, etc., compared to the microwave band. This thesis mainly involves five millimeter-wave antennas with different performance such as wideband, polarization-reconfigurable, beam-steerable, etc. These antennas are implemented based on the forms of transmitarray and reflectarray antennas to cope with the increasingly complex electromagnetic environments and various application scenarios.

A wideband transmitarray antenna is proposed based on polarization-rotating elements. Two elements with different configurations are designed to offer a 2-bit transmission phase in a wide band with high transmission efficiency without resizing their dimensions. A wideband 3-D printed reflectarray antenna is studied with mechanically reconfigurable polarization by using dielectric-based elements. Four elements are proposed to provide a 90-degree out of phase for transverse electric (TE) and transverse magnetic (TM) incidence waves and a 2-bit reflection phase simultaneously. By rotating the reflective panel that is implemented with the proposed four elements, the proposed reflectarray antenna is capable of offering linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP) in a wide band. Different from the currently beam-steerable reflectarray antennas enabled by loading PIN diodes, a low-cost, high-efficiency, and full-metal reflectarray antenna is studied to achieve 2D beam-steerable capabilities. A full-metal element is proposed to provide a 1-bit reflection phase for TE and TM incidence waves. By mechanically controlling the rotation of each element, the proposed reflectarray antenna will be able to achieve flexible beams as expected.

Dual-band and triple-band shared-aperture antennas are firstly developed with high figures of merit by combining the transmitarray/reflectarray and Fabry-Perot antennas. These shared-aperture antennas provide solutions to achieve dual-polarization, low loss, simple configuration, high aperture reuse efficiency, and the number of the operating bands in the designs of shared-aperture antennas.

Assessment Committee
Professor Søren Bech, Aalborg University, Denmark (Chairman)
Professor Jorge Rodrigues da Costa, University Institute of Lisbon, Portugal
Professor Niels Kuster, Eidgenössische Technische Hochschule Zürich, Switzerland

Supervisors
Professor Gert Frølund Pedersen, Aalborg University, Denmark
Associate Professor Shuai Zhang, Aalborg University, Denmark

Moderator
Associate Professor Jan H. Mikkelsen, Aalborg University, Denmark

After the defence there will be a reception at Fredrik Bajers Vej 7B2-109

Price

Free of charge

Host

Antennas, Propagation and Millimetre-Wave Systems Department of Electronic Systems

Address

Aalborg University, Fredrik Bajers Vej 7B2-107