Optimization of Conformal Low Profile Dipole Antennas

Open Access
Author:
Hariharan, Aditya
Graduate Program:
Electrical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 19, 2010
Committee Members:
  • James Kenneth Breakall, Thesis Advisor
Keywords:
  • Low profile dipoles
  • Open sleeve antennas
Abstract:
A study of horizontal low profile (close to the ground) open sleeve dipole antennas was carried out. The open sleeve dipole is a well established technique of increasing the bandwidth of a conventional dipole. By introducing parasitic elements in the vicinity of the driven element the impedance is slightly desensitized to changes in frequency. The objective was to see if such open sleeve dipoles at distances of less than 0.1 wavelength from a PEC ground plane would be a feasible alternative to conventional patch antennas for use in conformal applications. Typically horizontal dipoles close to the ground have low radiation resistance and act as poor radiators. Also they have a high impedance mismatch with typical feed systems (50 ohms or 75 ohms) making them impractical for use in certain applications. Simulations using FEKO showed that such low profile antennas based on the open sleeve idea could be constructed close to a PEC ground using thin wires and still have acceptable VSWR characteristics. Conformal variants of such antennas were then built - using thin conducting strips (instead of thin wires) on suitable substrates - and tested to verify the simulation results. These substrates in addition to providing mechanical backing to the antenna also reduce its effective length thus permitting miniaturization of the antenna. The design of these antennas and their results of this study are presented in the thesis. A qualitative comparison between the VSWR obtained using simulations and measurements seems to suggest the possibility of using these open sleeve dipole designs for conformal low-profile antenna applications.