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Proceedings Paper

An improved chip antenna circuit model for wideband matching
Author(s): Allen Hollister; John T. Armstrong
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Paper Abstract

An improved antenna circuit model is presented, which utilizes a transmission line to rotate s11 values to better fit measured data. Antennas are frequently modeled as either a series or parallel resonant circuit, the results of which are only exact over a small range of frequencies in the vicinity of resonance. These simple models are inadequate at frequencies distant from the antenna resonant frequency, however. Single-point matching, which preserves impedance match near resonance, cannot be used to design matching networks where there is a requirement to operate on frequencies other than the natural resonant frequency of the antenna, while maintaining a good impedance match. This paper describes an antenna model that uses a transmission line as a modeled circuit component. The transmission line allows the modeled impedances to be rotated about the Smith chart (transformed) in such a way as to closely match measured antenna impedance data from a vector network analyzer. The resulting matching network is valid over a very wide range of frequencies and allows precision matching networks (within a measurement error of ~2%) to be created. Measured results from a variety of antennas show high correlation with the theoretical circuit model.

Paper Details

Date Published: 24 May 2011
PDF: 12 pages
Proc. SPIE 8061, Wireless Sensing, Localization, and Processing VI, 80610K (24 May 2011); doi: 10.1117/12.885038
Show Author Affiliations
Allen Hollister, Physical Optics Corp. (United States)
John T. Armstrong, Probe Science, Inc. (United States)

Published in SPIE Proceedings Vol. 8061:
Wireless Sensing, Localization, and Processing VI
Sohail A. Dianat; Michael David Zoltowski, Editor(s)

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