Use this URL to cite or link to this record in EThOS:
Title: Time-modulated reflector-arrays
Author: Wang, Yang
ISNI:       0000 0004 5347 2802
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2015
Availability of Full Text:
Access from EThOS:
Access from Institution:
This PhD thesis introduces the time-modulated reflector-arrays which are a hybrid of conventional time-modulated array (TMA) systems and reflectarrays. The TMRAs use a similar layout of reflectarray feed by a source. Compared to conventional phased arrays, reflectarrays and time-modulated arrays, a TMRA is potentially simpler to implement in hardware as it does not need a complicated feeding network or the use of the phase shifting units. Instead of phase shifting units, TMRAs use discrete time-switching to achieve beamforming functions. The concept and operating mechanism of the TMRA is explained using a simple model based on isotropic scatterers. A more sophisticated TMRA based on an 8 element array of PIN-diode controlled bow-tie dipole elements is designed and analysed using a full-wave commercial simulator. A hardware implementation of the bowtie dipole TMRA system, including control circuitry, is also described and measured data is presented. The simulated and measured results confirm that the time-modulated reflector array system performs the required function of harmonic beam steering. Moreover, TMRAs can provide functions such as sidelobe suppression and adaptive beamforming. The thesis also provide solutions to the challenges of TMRAs such as low system efficiency and phases variances caused by feeding paths. Overall TMRAs combine the benefits of conventional TMA systems and reflectarrays. They can provide similar functions of conventional TMAs, phased arrays and reflectarrays without the need of expensive phase shifters and lossy transmission lines. This makes TMRAs a very good candidates in applications over millimetre-wavelength frequency band.
Supervisor: Tennant, Alan ; Langley, R. J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available