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Full text release has been delayed at the author's request until May 08, 2024

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Vanadium Dioxide Reflectarray Antennas

Ramsey, Jordan Ashley
http://orcid.org/0000-0001-6945-0489
http://rave.ohiolink.edu/etdc/view?acc_num=osu1672570965941502

Abstract Details

2023, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Reflectarray antennas combine the best features of parabolic reflectors and phased arrays. Able to achieve high gain and low loss, reflectarray antennas are a simple, low profile method of beam scanning. Parabolic reflectors, while directive are both bulky and heavy making the manufacturing process extremely expensive. Furthermore, phased arrays support seamless beam steering, but require several electronic components to control. Reflectarrays, lightweight, planar and simply manufactured, remove the complexities common in the alternative devices. Microstrip reflectarrays are the most commonly constructed reflectarray designs. Due to the maturity of microstrip technology, several microstrip reflectarrays have been explored throughout literature. The foundation of reflectarray development is the unit cell element. Designed to produce a phase variation across the aperture surface, the physical dimensions of the unit cell are varied such that the reflected field is controlled producing a focused beam. In the case of fixed beam reflectarrays, with a wide range of design possibilities there still exists limitations in element design at higher frequencies. Because the dimensional tolerances decrease inversely to frequency, single layer high frequency microstrip reflectarrays are unable to achieve the full phase range where aperture space is limited. To circumvent these restrictions, multi-layer reflectarrays provide a wider phase range by increasing the number of tuning parameters. Such designs include several layers of patterned elements and substrates vertically stacked on top of one another, where the dimension of the elements on each layer are optimized. However, the addition of multiple dielectric and metallic layers increases the number of fabrication steps adding to the convolution. On the other hand, phase reduction using quantization has been applied frequently to reflectarray development. Here, rather than increasing the number of tuning dimension, the phase range is compensated by establishing unique states greatly reducing design challenges. To support beam steering, the phase of the unit cell element is tuned through the addition of adaptable components. Most often implemented using PIN and varactor diodes, recently, studies have reported the success of element tuning using controllable materials. Liquid crystal has been successfully integrated into several beam steering reflectarrays. Phase adjustment is achieved by applying a bias voltage controlling the orientation of the internal molecules. Consequentially, the change in material permittivity modulates the elements resonance and phase. However, with low dielectric anisotropy at mmWave frequencies, the phase of liquid crystal reflectarray elements is limited. Barium strontium titanate (BST) has also been explored as electrically responsive material used for element tuning yet suffers from increased losses at high frequencies. This research proposes the use of vanadium dioxide (VO2) as a method of both element phase compensation and full device reconfiguration. As a thermally responsive phase change material, the resistivity of VO2 decreases several orders of magnitude above the transition temperature. This is exploited through the integration of a VO2 thin film into a 1⁄4 λ0 single layer unit cell operating at 35 GHz. At the unit cell level, the VO2 operates as a capacitive switch, which is then implemented in the design, fabrication and measurement of several 10 λ0 ×10 λ0 quantized fixed beam and dual state reflectarray devices.
Nima Ghalichechian (Advisor)
Shamsul Arafin (Committee Member)
Asimina Kiourti (Committee Member)
Electrical Engineering; Electromagnetics

Recommended Citations

Citations

  • Ramsey, J. A. (2023). Vanadium Dioxide Reflectarray Antennas [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1672570965941502

    APA Style (7th edition)

  • Ramsey, Jordan. Vanadium Dioxide Reflectarray Antennas. 2023. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1672570965941502.

    MLA Style (8th edition)

  • Ramsey, Jordan. "Vanadium Dioxide Reflectarray Antennas." Doctoral dissertation, Ohio State University, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=osu1672570965941502

    Chicago Manual of Style (17th edition)

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