University of Illinois Urbana-Champaign

Log-Periodic Baluns

Wan, Fang

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https://hdl.handle.net/2142/46509

Description

Title
Log-Periodic Baluns
Author(s)
Wan, Fang
Contributor(s)
Bernhard, J.
Issue Date
2012-05
Keyword(s)
  • antennas
  • baluns
  • log periodic baluns
  • high-frequency structure simulation
Abstract
Baluns used in modern antenna applications for low frequency ranges often only cater to one frequency and only work for connections from a coaxial to a twin feed. To handle signals that have a wider frequency band of operation, multiple baluns would have to be used. But, these baluns do not solve the imbalance caused by the skin effect of the coaxial at the feed-point. In this paper, we propose a solution based on the idea of log-periodicity. Resonant LC circuits are implanted between the outer shield of the coaxial cable and the inner walls of the balun to create short circuits at different resonant frequencies, essentially generating shorter balun structures that apply to higher frequencies. A log-periodic pattern was used to determine the space between the resonant circuits. High Frequency Structure Simulator (HFSS) simulations showing the current density on the structure proved that the design helped to alleviate imbalance problems caused operation at non-resonant frequencies. A higher Common-Mode Rejection Ratio (CMRR) is also observed over a frequency band of IGHz, though peak CMRR values were encountered at frequencies slightly lower than the resonant frequencies the structure was designed for. A log-periodic balun prototype was built to verify these simulation results.
Type of Resource
text
Language
en
Permalink
http://hdl.handle.net/2142/46509

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