Theory and Applications of a Uniplanar Transmission-Line Metamaterial-Inspired Electromagnetic Bandgap Structure

• Author / Creator

  Barth, Stuart E

• A multitude of planar electromagnetic bandgap structures (EBGs) have been proposed for the suppression of parallel-plate waveguide (PPW) and surface-wave (SW) modes at microwave frequencies. Some of these structures have been well-modelled with transmission-line theory, however, these structures typically employ vias which prevent these structures from being used at high frequencies or in low-cost applications, where vias can be difficult or expensive to manufacture. Alternatively, EBGs have been proposed which overcome this limitation with a uniplanar design, such that they are simple to manufacture using standard lithographic processes. However, these structures generally suffer from the lack of a rigorous model, such that the bandgap properties are difficult to control without changing the overall size of the EBG.

  This work seeks to overcome this limitation through the development of a uniplanar EBG structure which is shown to be well-described by a proposed multiconductor transmission-line model. Transmission-line metamaterial techniques are then used to miniaturize the EBG's constituent unit cells, without any loss of model accuracy. Although this EBG is inherently one-dimensional, it is shown that it can be arranged radially to effect suppression in two dimensions.

  The EBG is created by loading the coplanar waveguide (CPW) conductors of a shielded, conductor-backed CPW (S-CBCPW) structure with series capacitors and shunt inductors, as inspired by transmission-line metamaterials. The bandgaps used in this work are shown to arise through modal coupling, in which the loaded CPW mode couples with the PPW and/or SW modes to prevent the transmission of power.

  To demonstrate the effectiveness and versatility of this EBG, it is applied to two applications: the suppression of parallel-plate noise between two vias at X-band, and the suppression of the SW mode on a GPS antenna ground plane at L-band. It is shown that the full-wave simulated results agree well with the periodic analysis of the equivalent-circuit model developed in this work. Finally, the designed EBGs were manufactured and tested to verify these results. Several avenues of further study and applications are suggested.

• Subjects / Keywords

  • Metamaterial
  • GPS
  • Electromagnetic Bandgap Structure
  • Parallel-Plate
  • Transmission Line
  • Microwave
  • Surface Wave

• Graduation date

  Fall 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3057D37X

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.