Comparison of Accuracy of Simulations of Stepped-Diameter Yagi Antennas

Open Access
Adams, Kimberly Lynn
Graduate Program:
Electrical Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 21, 2012
Committee Members:
  • James Kenneth Breakall, Thesis Advisor
  • Yagi antenna
  • GNEC
  • FEKO
  • stepped-diameter antenna
Stepped-diameter Yagi antennas are used in multiple applications and are often designed with computer simulations. These computer simulations can take geometry input and visualize both the geometry and output to focus on needed desired behaviors. The antenna simulation software GNEC has shown to be accurate with both constant diameter Yagis and stepped-diameter Yagis. One of the purposes of this thesis is to show if the newer software FEKO can also model constant and stepped-diameter Yagi antennas with the same modeling guideline rules, mainly segment size in wavelengths, as in GNEC. Complex Yagi antennas did not model in FEKO as well as in GNEC using the same basic rule for segment sizes, so a comparison of several Yagi antennas in two different simulation programs were compared to identify any trends and also compare with measurements when available. A constant diameter Yagi, a stepped-diameter Yagi, stacked stepped-diameter Yagis and a multiband stepped-diameter antenna were modeled in GNEC and FEKO. Results were compared between the simulation programs and compared to available measured results. The output from FEKO was shown to be shifted from measured results proportional to frequency, in relation to segment sizes. The antennas in FEKO were found to require segment sizes five times smaller than the minimum required for GNEC. This was true for both constant and stepped-diameter antennas. It is recommended that a FEKO user always use a custom selected segment size less than or equal to λ/100 and not use the default selections.