Title page for ETD etd-080699-180221


Type of Document Master's Thesis
Author Kim, Jeong I.
Author's Email Address jekim2@vt.edu
URN etd-080699-180221
Title Log-Periodic Loop Antennas
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Safaai-Jazi, Ahmad Committee Chair
Poon, Ting-Chung Committee Member
Stutzman, Warren L. Committee Member
Keywords
  • Log-Periodic Loop Antenna
  • Log-Periodic Dipole Antenna
  • Ground Reflector
  • ESP
  • Frequency Independent Antenna
Date of Defense 1999-07-27
Availability unrestricted
Abstract
The Log-Periodic Loop Antenna with Ground Reflector (LPLA-GR) is investigated as a new type of antenna, which provides wide bandwidth, broad beamwidth, and high gain. This antenna has smaller transverse dimensions (by a factor of 2/pi) than a log-periodic dipole antenna with comparable radiation characteristics. Several geometries with different parameters are analyzed numerically using ESP code, which is based on the method of moments. A LPLA-GR with 6 turns and a cone angle of 30* offers the most promising radiation characteristics. This antenna yields 47.6 % gain bandwidth and 12 dB gain according to the numerical analysis. The LPLA-GR also provides linear polarization and unidirectional patterns.

Three prototype antennas were constructed and measured in the Virginia Tech Antenna Laboratory. Far-field patterns and input impedance were measured over a wide range of frequencies. The measured results agree well with the calculated results. Because of its wide bandwidth, high gain, and small size, the LPLA is expected to find applications as feeds for reflector antennas, as detectors in EMC scattering range, and as mobile communication antennas.

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