TECHNIQUES FOR DESIGNING MICROWAVE AND MILLIMETER WAVE ANTENNAS AND COMPONENTS USING ARTIFICIALLY ENGINEERED MATERIALS AND METASURFACES

Restricted (Penn State Only)
Author:
Pandey, Shaileshachandra V
Graduate Program:
Electrical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 10, 2017
Committee Members:
  • Dr. Raj Mittra, Dissertation Advisor
  • Dr. Ram Narayanan, Committee Chair
  • Dr Jim Breakall, Committee Member
  • Dr. MICHAEL T LANAGAN, Committee Member
  • Dr. MICHAEL T LANAGAN, Outside Member
Keywords:
  • FSS
  • Artificial Engineered material
  • Lens
  • Variable phase-shifter
  • Space-qualifiable Lens
  • Metal-only Reflectarray
  • Dielectric-only Reflectarray
  • DaD Lens
  • Dual-band Metal-only reflectarray
Abstract:
Recent years have witnessed extensive research into the synthesis of new materials (e.g., metamaterials that typically utilize periodic structures). It is well known that periodic structures comprising metallic patches or apertures behave as artificial dielectrics, and screens that resemble frequency selective surfaces (FSSs) can be used as artificially synthesized materials to replace conventional dielectrics. Several designs have been developed for some applications where metamaterials were engineered by utilizing arrays of small patches or apertures to realize desired electromagnetic behavior for antenna applications, thus improving their performance. This dissertation begins with an innovative approach for engineering artificial materials or commercial-off-the-shelf (COTS) materials to achieve any dielectric constants that we need to implement flat lens design, which does not suffer from the shortcomings of metamaterials, typically required in designs based on transformation optics (TO). We refer to this technique as “dial-a-dielectric” (DaD). The DaD method is the one in which we tweak the dielectric constants of the artificial material by placing square patches on top of dielectric rings, to achieve the desired dielectric constants. We investigate the use of the proposed technique for synthesizing artificial dielectrics to the design of metasurfaces (e.g., reflectarrays) that have wider bandwidths than those of the present designs, which also utilize resonant elements that rely on resonant inclusions (e.g., narrow bandwidth, dispersion, and loss). Next, we introduce an alternate design that extends the DaD-based lens design procedure to the dielectric-only reflectarray problem. This reflectarray design is realized by printing dielectric blocks on a PEC ground plane. The proposed reflectarray design gives a linearly increasing gain variation compared to the bandwidth as typically reported in the literature (i.e., 10% for the designs based on the conventional approach). This dissertation further explores the design of a flat lens, which utilizes multilayer frequency selective surfaces (FSSs) in free space. The lens can be space-qualified since, unlike conventional designs for lenses, it does not need to use dielectric materials. We further describe a systematic procedure for realizing the requisite radially varying phase shifts, by using locally periodic multilayer FSSs to realize a lightweight, low-profile and low-cost design. Next, we present a novel approach for designing a low-cost phase-shifting device based on the use of reconfigured FSS screens, which have relatively low insertion loss and are easy to fabricate. Our goal is to provide an arbitrary phase shift to the antenna element of an array that it would require for precise control of the beam-pointing to communicate with a satellite. Lastly, offset-fed-metal-only reflectarrays realized by using cross-slot and cross/cross-groove phasing elements, which are 2D and 3D FSS elements, respectively, are presented. These reflectarray designs are suitable for space applications in which the use of dielectrics is not desired. These FSS elements are chosen such that they can be 3D-printed. We also compare the performances of reflectarrays with the existing metal-only reflectarray design to show the efficacy of the proposed method. The design investigated shows the improved gain, aperture efficiency, and low-profile features.