Browsing by Author "Apperley, Thomas"

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    A Proof-of-Concept Micro-Pneumatically Controlled Reconfigurable Dielectric Resonator Antenna
    (2013-09-25) Apperley, Thomas; Okoniewski, Michal
    The dielectric resonator antenna (DRA) has several advantages over metallic antennas, which may include low-loss and compact design. However, few frequency reconfiguration methods exist for the DRA. This thesis proposes, designs and validates a new frequency reconfigurable DRA. A proof-of-concept prototype was designed on 101.6 mm x 101.6 mm x 0.508 mm PCB. Frequency reconfigurability was achieved by changing the coupling capacitance between the DRA's fundamental mode and the antenna ground plane by sliding metalized slugs of PCB (3.5 mm x 5.0 mm x 0.29 mm) either under or away from the DRA. The prototype had a measured tuning range of 24.7 % and had two operating frequencies: 21.4 GHz and 16.6 GHz, each with bandwidths of 9.72 % and 6.05 % respectively. The E-plane and H-plane broadside radiation patterns were also measured and were fairly consistent between high and low frequency operation. Keywords: dielectric resonator antennas, frequency reconfigurable antennas
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    ItemOpen Access
    A Modular System for Radio Frequency Heating of Hydrocarbon Reservoirs
    (2019-10-29) Apperley, Thomas; Okoniewski, Michal M.; Nielsen, John; Belostotski, Leonid; Fear, Elise C.; O'Keefe, Kyle P. G.; Bridges, Greg
    Radio frequency (RF) heating is an enhanced oil recovery method with the potential to revolutionize oil sands resource development. In the author's opinion, RF heating currently faces four major practical challenges: heating pattern control, downhole transmission loss, sensitivity to changing reservoir environments and the cost and efficiency of RF generation. This thesis pursues a system concept and laboratory prototypes that can address these issues. The first two challenges can be addressed using a modular system. Sensitivity to the reservoir can be resolved using a single conductor transmission line launcher with two coaxial discontinuities and field quasi-symmetry, which was validated using a frequency-scaled prototype. Power combined switching oscillators can ensure high-efficiency RF generation at high output power, while the use of silicon carbide transistor technology can prospectively reduce cost while providing ruggedness. A new E/Fodd oscillator was devised and a prototype using two power combined oscillators is presented.