A Numerical Parametric Study on the Performance of a Low Profile dipole Planar Inverted Cone Antenna Placed over an Electromagnetic Bandgap Structure
AuthorBlitstein, Adam M.
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Electromagnetic Band-gap (EBG) materials are a type of metamaterial with attractive properties not found in nature. EBG materials act as a high impedance surface over a specific frequency range, so they are a good candidate for replacing the conductive ground plane found in most low profile antennas. In this thesis, the effect of EBG materials on a low profile dipole planar inverted cone antenna (LPdiPICA) is investigated. A simple and effective design procedure for deriving the parameters for the Sievenepiper mushroom-like EBG structure is presented. When an optimized EBG substrate replaced the conductive ground plane on the LPdiPICA, it was found that the impedance bandwidth remained large (4.5:1), the broadside minimum at 4 GHz improved by 13.29 dB, but the pattern bandwidth decreased to 3.4:1 .The patch width, gap width, and via diameter were all varied, and It was revealed that each parameter sweep only minimally changed the impedance match and affected only the radiation pattern near the EBG resonant frequency. It was concluded that an EBG substrate can be designed to improve the radiation pattern without affecting the impedance match. The antenna height above the substrate was also varied, but the impedance match quickly degraded past acceptable levels.Lastly, a lower profile version of the LPdiPICA was designed for the 2.4 GHz and 5.8 GHZ industrial, scientific and medical (ISM) bands. The LPdiPICA was placed above the EBG surface such that the overall height was less than 0.1λ. The EBG surface greatly improved the impedance match in each band, but the compromise was reduced gain.