School of
Information Technology and Electrical Engineering

Speaker: Md Shahidul Alam
Seminar Date: Fri, 02/02/2018 - 14:30
Venue: 78-346
Host: Prof Amin Abbosh

Seminar Type:  PhD Thesis Review

Abstract: 

Antenna is a crucial and frontier element in the core of any communication systems for transceiving signals in the form of electromagnetic radiation. Traditionally, antenna design and its performances are optimized for fixed frequency, radiation and polarization characteristics. Modern electronic and wireless communication technologies demand compact, multifunctional antennas to adapt with the changing system requirements. Fixed performance antennas (FPA) are incapable of meeting changes in the operating environments as they possess static characteristics in terms of frequency, polarization and radiation. In this perspective, reconfigurable antennas (RA) are impressive due to their dynamic ability to adapt in the changing scenarios and address the changes in the system requirements. Being multifunctional, an RA can substitute several FPAs, thus provides compactness, minimizes costs, and simplifies system integration in addition to the flexibility of performances and improved functionality. Antenna reconfigurability can be achieved by mechanical, electronic or material property controls, however, due to the incorporated control techniques and design process, the performance of reconfigurable antennas becomes limited and inconsistent in different reconfigurable states. Besides, as part of the reconfiguration process, use of multiple feeding, additional impedance matching networks and/or compound controlling mechanisms increase the antenna size, profile and control complexity. This research focuses on building compact sized and low profile reconfigurable antennas with simplified reconfiguration mechanisms and consistent reconfigurability performances. Towards this, several reconfigurable antenna concepts having single and multiple reconfigurability functions have been developed and proposed. The initial planar designs indicate that structural symmetry helps to achieve uniform reconfiguration and performance stability in all states. Frequency reconfigurability concept is studied on an ultra-wideband (UWB) antenna for reconfigurable band-rejection of the WiMax and WLAN bands. Pattern reconfigurable antennas are designed for 360˚ beam-scanning with different steering steps and stable gain profiles. Some techniques to improve the antenna gain and impedance matching are proposed. Next, integrated multiple reconfigurability functions are realized with two different antenna models that can tune the resonant frequency and also scan the radiation beam in different azimuth and elevation directions. Finally, a high gain tunable travelling-wave antenna is proposed that is capable to tune the resonance across a wideband and scan the pencil beam radiation at each frequency within the tuning range. The reconfigurability performances of the proposed antennas are predicted by electromagnetic simulators and validated by testing fabricated prototypes in the antenna measurement lab. The proposed antenna concepts and obtained results can be used as design considerations for building reconfigurable antennas for future communication systems. 

Biography: 

Md Shahidul Alam received his B.Sc. in Electrical and Electronic Engineering from Chittagong University of Engineering and Technology (CUET), Bangladesh in 2008 and M.Sc. (By Research) in Electrical, Electronic and Systems Engineering from Universiti Kebangsaan Malaysia (UKM), Malaysia in 2013. Currently he is a final year PhD student in the School of Information Technology and Electrical Engineering at The University of Queensland, Australia. His research interests include reconfigurable antennas for micro- and mm-wave communication systems, compact beam scanning systems, on-the-move communications etc.