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Title: Tunable microwave and millimetre-wave metamaterial structures and applications
Author: Mavridou, Marina
ISNI:       0000 0004 5368 3909
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2015
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Novel designs of metamaterial structures as well as novel techniques and configurations for tuning metamaterials are presented in this PhD thesis. The proposed tuning techniques overcome the challenges that exist in other tuning techniques available thus far. Moreover, possible applications of tunable metamaterials in communication systems are proposed. Initially, tunable Electromagnetic Band-Gap (EBG) structures are proposed for low frequencies operation (3GHz to 6GHz) employing a novel biasing technique for varactor diodes. Subsequently, the proposed tunable EBG structures are applied to closely spaced antennas, achieving isolation enhancement for MIMO systems. Moreover, a new technique of tuning High Impedance Surface (HIS) structures is presented, with low-loss performance and no parasitic effects, based on employing two types of piezoelectric actuators, each type being suitable to a different frequency band. Particularly, bender piezoelectric actuators are used for configurations operating at low mm-wave frequencies (~15GHz) and stack multilayer actuators for operation at higher mm-wave frequencies (60GHz) where achieving a low loss performance is even more challenging. Two tunable antenna designs are also proposed incorporating both tunable HIS structures (at 15GHz and 60GHz). Finally, novel configurations of tunable Frequency Selective Surfaces (FSS) are proposed based on the concept of piezoelectric actuators to obtain a tunable response. Again, this is carried out for two operating bands, 15GHz and 60GHz. The particular designs of tunable HIS and FSS, are directly scalable to even higher frequencies (THz), offering a promising solution at this band.
Supervisor: Not available Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TK Electrical engineering. Electronics Nuclear engineering