A variety of antenna tuning techniques exist for conventionally constructed antenna structures, such that when an antenna is converted from a design to an actual fabricated structure, slight adjustments can be made to the fabricated structure to match the performance expected from the design. For microstrip antenna structures, for example, shorting pins may be added to adjust the resonant frequency of the structure, or the conducting top layer of the antenna may be intentionally constructed in a fashion such that portions of it may be removed in post-production tuning.

(Left) The e-textile microstrip patch antenna, and (right) with tuning stitches added.
For e-textile-based antenna structures, these tuning techniques are not as easily realized, e.g. an e-textile microstrip antenna may be stitched to an e-textile substrate in a fashion that does not allow portions of the antenna top conductor to be removed post-production, particularly at the edges of the structure.

E-textile antennas enable novel methods to be introduced for post-production tuning of antennas that are not possible with conventionally constructed designs. The present innovation is one such method, whereby the e-textile antenna structure may be tuned through the addition of tuning stitches.

One implementation of the innovation is the application to the tuning of a microstrip patch antenna. Following the addition of the first stitch, the resonance shifted to 935 MHz (3.2% change). Adding a second stitch shifts the resonant frequency to 925 MHz (4.1% change).

This work was done by Timothy Kennedy, Patrick Fink, Andrew Chu, and Gregory Lin of Johnson Space Center. MSC-25288-1

NASA Tech Briefs Magazine

This article first appeared in the January, 2015 issue of NASA Tech Briefs Magazine.

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